Chemical Acute Exposure Guideline Levels (AEGLs)

The Environmental Protection Agency has listed a group of chemicals to prevent acute exposure to in the future environment. This list includes very toxic chemicals to humans, animals and plants. First AEGL Chemical Priority List The First AEGL Chemical Priority List appeared in the May 21, 1997 Federal Register Page 27733-27734 and listed 85 chemicals. An additional 15 chemicals were added to this list subsequently. All 100 First AEGL Chemical Priority List chemicals were viewed as high priority for AEGL development, based on their nomination by AEGL Committee stakeholders and overlap of interest among many different organizations. CAS No. Chemical Name 56-23-5................................... Carbon tetrachloride 57-14-7................................... 1,1-Dimethyl hydrazine 60-34-4................................... Methyl hydrazine 62-53-3................................... Aniline 67-56-1................................... Methanol 67-66-3................................... Chloroform 68-12-2................................... Dimethylformamide 71-43-2................................... Benzene 74-90-8................................... Hydrogen cyanide 74-93-1................................... Methyl mercaptan 75-09-2................................... Methylene chloride 75-21-8................................... Ethylene oxide 75-44-5................................... Phosgene 75-55-8................................... Propyleneimine 75-56-9................................... Propylene oxide 75-74-1................................... Tetramethyllead 75-77-4................................... Trimethychlorosilane 75-78-5................................... Dimethyldichlorosilane 75-79-6................................... Methyltrichlorosilane 75-86-5................................... Acetone cyanohydrin 77-81-6................................... Tabun (GA) 78-82-0................................... Isobutyronitrile 78-93-3................................... Methyl ethyl ketone 79-01-6................................... Trichloroethylene 79-10-7................................... Acrylic acid 79-11-8................................... (mono-)Chloroacetic acid 79-21-0................................... Peracetic acid 79-22-1................................... Methyl chloroformate 91-08-7................................... Toluene 2,6-diisocyanate 96-64-0................................... Soman (GD) 106-89-8................................. Epichlorohydrin 107-02-8................................. Acrolein 107-11-9................................. Allyl amine 107-12-0................................. Propionitrile 107-15-3................................. Ethylenediamine 107-18-6................................. Allyl alcohol 107-30-2................................. Chloromethyl methyl ether 107-44-8................................. Sarin (GB) 108-23-6................................. Isopropyl chloroformate 108-88-3................................. Toluene 108-91-8................................. Cyclohexylamine 108-95-2................................. Phenol 109-61-5................................. Propyl chloroformate 110-00-9................................. Furan 110-89-4................................. Piperidine 123-73-9................................. Crotonaldehyde, (E) 123-91-1................................. 1,4-Dioxane 126-98-7................................. Methacrylonitrile 127-18-4................................. Tetrachloroethylene 151-56-4................................. Ethyleneimine 302-01-2................................. Hydrazine 329-99-7................................. Cyclohexylmethyl phosphono fluoridate GF 353-42-4................................. Boron triflouride compound with methyl ether (note: boron trifluoride CAS # is 7637-07-2) 505-60-2................................. Sulfur mustard 506-77-7................................. Cyanogen chloride 509-14-8................................. Tetranitromethane 540-59-0................................. 1,2-Dichloroethylene 540-73-8................................. 1,2-Dimethylhydrazine 584-84-9................................. Toluene 2,4-diisocyanate 594-42-3................................. Perchloromethylmercaptan 624-83-9................................. Methyl isocyanate 630-08-0................................. Carbon monoxide 811-97-2................................. HFC 134A (1,1,1,2-Tetrafluoroethane) 814-68-6................................. Acrylyl chloride 1330-20-7............................... Xylenes (mixed) 1717-00-6............................... HCFC 141b (1,1-Dichloro-1-fluoroethane) 4170-30-3............................... Crotonaldehyde 6423-43-4............................... Otto Fuel II 7446-09-5............................... Sulfur dioxide 7446-11-9............................... Sulfur trioxide 7647-01-0............................... Hydrogen chloride 7647-01-0............................... Hydrochloric acid 7664-39-3............................... Hydrogen fluoride 7664-41-7............................... Ammonia 7664-93-9............................... Sulfuric acid 7697-37-2............................... Nitric acid 7719-12-2............................... Phosphorus trichloride 7726-95-6............................... Bromine 7782-41-4............................... Fluorine 7782-50-5............................... Chlorine 7783-06-4............................... Hydrogen sulfide 7783-60-0............................... Sulfur tetrafluoride 7783-81-5............................... Uranium hexafluoride 7784-34-1............................... Arsenous trichloride 7784-42-1............................... Arsine 7790-91-2............................... Chlorine trifluoride 7803-51-2............................... Phosphine 8014-95-7............................... Oleum 10025-87-3.............................. Phosphorus oxychloride 10049-04-4.............................. Chlorine dioxide 10102-43-9.............................. Nitric oxide 10102-44-0.............................. Nitrogen dioxide 10294-34-5.............................. Boron trichloride 13463-39-3.............................. Nickel carbonyl 13463-40-6.............................. Iron, pentacarbonyl- 19287-45-7.............................. Diborane 25323-89-1.............................. Trichloroethane 50782-69-9.............................. VX 163702-07-6............................ Methyl nonafluorobutyl ether (HFE 7100 component) 163702-08-7............................ Methyl nonafluorobutyl ether (HFE 7100 component) Second AEGL Chemical Priority List [New Replace Term] This list of 371 priority chemicals is a composite of numerous priority lists of acutely toxic chemicals and represents the selection of chemicals for AEGL development by the NAC/AEGL during the next several years. The list has been assembled from the individual lists of chemicals nominated by NAC/AEGL member organizations for AEGL development. The priority list of chemicals, published in notice, is subject to modification as priorities of the NAC/AEGL committee or the NAC/AEGL member organizations change, it is anticipated that most of the chemicals on the priority list will remain as higher priority for AEGL development during the next several years. The NAC/AEGL intends to address at least 30 chemicals per year in the AEGL development process. There are 137 chemicals on this list of 371 priority chemicals that are considered a higher priority (indicated by an asterisk below), based on considerations of toxicity, volatility, presence on numerous organization chemical lists, and other factors. These chemicals are planned to be addressed prior to the other listed chemicals. It is believed that publication of today's list of chemicals will provide individuals and organizations with ample time to gather existing data and information and, where appropriate, to develop new data and information on the acute toxicity of the chemicals listed herein, for the consideration of the NAC/AEGL Committee. Parties possessing such data and information or those anticipating the future conduct of toxicity studies on any of these chemicals should contact the Designated Federal Officer. Second List of AEGL Priority Chemicals for Guideline Development CAS No. Chemical Name 50-00-0................................... Formaldehyde* 50-29-3................................... 4,4'-DDT 50-32-8................................... Benzo(a)pyrene* 54-11-5................................... Nicotine 56-38-2................................... Parathion* 56-55-3................................... Benzo(a)anthracene 56-72-4................................... Coumaphos 57-24-9................................... Strychnine* 57-57-8................................... Beta-Propiolactone 57-74-9................................... Chlordane* 58-89-9................................... Lindane (hexachlorocyclohexane) 60-29-7................................... Ethyl ether 60-51-5................................... Dimethoate 60-57-1................................... Dieldrin 62-38-4................................... Phenylmercuric acetate* 62-73-7................................... Dichlorvos 62-74-8................................... Sodium fluoroacetate* 62-75-9................................... Nitrosodimethylamine 64-18-6................................... Formic acid 64-19-7................................... Acetic acid 67-64-1................................... Acetone* 74-82-8................................... Methane 74-83-9................................... Methyl bromide* 74-87-3................................... Methyl chloride* 74-88-4................................... Methyl iodide 74-89-5................................... Methyl amine* 74-98-6................................... Propane* 75-00-3................................... Chloroethane 75-01-4................................... Vinyl chloride* 75-02-5................................... Vinyl fluoride 75-04-7................................... Ethyl amine* 75-05-8................................... Acetonitrile 75-07-0................................... Acetaldehyde* 75-08-1................................... Ethyl mercaptan* 75-12-7................................... Formamide 75-15-0................................... Carbon disulfide* 75-18-3................................... Dimethyl sulfide 75-25-2................................... Bromoform 75-34-3................................... 1,1-Dichloroethane 75-36-5................................... Acetyl chloride* 75-50-3................................... Trimethylamine* 75-54-7................................... Methyl dichlorosilane* 75-65-0................................... t-Butyl alcohol 75-93-4................................... Methyl sulfate 76-02-8................................... Trichloroacetyl chloride* 76-06-2................................... Chloropicrin* 76-44-8................................... Heptachlor 77-47-4................................... Hexachlorocyclopentadiene 77-78-1................................... Dimethyl sulfate* 78-00-2................................... Tetraethyl lead 78-71-7................................... Oxetane, 3,3- bis(chloromethyl)- 78-85-3................................... Methacrylaldehyde* 78-87-5................................... 1,2-Dichloropropane 78-94-4................................... Methyl vinyl ketone* 78-95-5................................... Chloroacetone (stabilized)* 78-97-7................................... Lactonitrile 79-04-9................................... Chloroacetyl chloride* 79-06-1................................... Crylamide 79-09-4................................... Propionic acid 79-14-1................................... Glycolic acid 79-19-6................................... Thiosemicarbazide 79-38-9................................... Trifluorochloroethylene 79-41-4................................... Methacrylic acid* 79-57-2................................... Terramycin* 80-15-9................................... Cumene hydroperoxide 80-56-8................................... alpha-Pinene 80-62-6................................... Methyl methacrylate* 80-63-7................................... Methyl 2-chloroacrylate 81-81-2................................... Warfarin 82-66-6................................... Diphacinone 84-66-2................................... Diethyl phthalate 84-74-2................................... di-n-Butyl phthalate 85-68-7................................... Butyl benzyl phthalate 86-50-0................................... Azinphos-methyl* 86-74-8................................... Carbazole 87-86-5................................... Pentachlorophenol 92-52-4................................... Biphenyl 94-75-7................................... 2,4-Dichlorophenyoxy acetic acid 95-48-7................................... o-Cresol 95-63-6................................... Trimethyl benzene 96-29-7................................... 2-Butanone oxime 97-02-9................................... 2,4-Dinitroaniline* 98-05-5................................... Phenyl arsonic acid 98-07-7................................... Benzyl trichloride 98-09-9................................... Benzenesulfonyl chloride 98-13-5................................... Trichlorophenyl silane 98-16-8................................... 3-(Trifluoromethyl) Aniline 98-82-8................................... Cumene 98-87-3................................... Benzal chloride 98-88-4................................... Benzoyl chloride 98-95-3................................... Nitrobenzene 100-14-1.................................. Benzene, 1-(chloromethyl)-4- nitro- 100-41-4.................................. Ethyl benzene 100-42-5.................................. Styrene* 100-44-7.................................. Benzyl chloride 100-51-6.................................. Benzyl alcohol 101-68-8.................................. 4,4-Methylenediphenyl diisocyanate* 103-71-9.................................. Phenyl isocyanate 105-60-2.................................. Caprolactam 106-44-5.................................. p-Cresol 106-50-3.................................. p-Phenylenediamine 106-88-7.................................. 1,2-Butylene oxide 106-93-4.................................. Dibromoethane* 106-96-7.................................. Propargyl bromide 106-97-8.................................. Butane* 106-99-0.................................. Butadiene* 107-05-1.................................. Allyl chloride 107-06-2.................................. 1,2-Dichloroethane 107-07-3.................................. Chloroethanol 75-05-8.................................. Acrylonitrile* 107-14-2.................................. Chloroacetonitrile* 107-16-4.................................. Formaldehyde cyanohydrin 107-19-7.................................. Propargyl alcohol 107-20-0.................................. Chloroacetaldehyde* 107-21-1.................................. Ethylene glycol 107-37-9.................................. Allyl trichlorosilane 107-72-2.................................. Amyltrichlorosilane 108-05-4.................................. *Vinyl acetate monomer 108-10-1.................................. 4-Methyl-2-pentanone 108-24-7.................................. Acetic anhydride* 108 31-6.................................. Maleic anhydride* 108-39-4.................................. m-Cresol 108-65-6.................................. Propylene glycol monomethyl ether acetate 108-67-8.................................. Mesitylene 108-90-7.................................. Chlorobenzene* 108-98-5.................................. Phenylmercaptan* 109-73-9.................................. n-Butylamine 109-77-3.................................. Malononitrile* 109-89-7.................................. Diethyl amine 109-90-0.................................. Ethyl isocyanate 109-99-9.................................. Tetrahydrofuran* 110-54-3.................................. Hexane* 110-57-6.................................. Trans-1,4-dichlorobutene 110-78-1.................................. n-Propyl isocyanate 110-82-7.................................. Cyclohexane* 110-86-1.................................. Pyridine 111-34-2.................................. Butyl vinyl ether 111-36-4.................................. n-Butyl isocyanate* 111-42-2.................................. Diethanolamine 111-44-4.................................. Dichloroethyl ether 111-48-8.................................. Thiodiglycol 111-69-3.................................. Adiponitrile 111-77-3.................................. Diethylene glycol monomethyl ether 111-88-6.................................. n-Octylmercaptan* 115-21-9.................................. Trichloroethyl silane 116-06-3.................................. Aldicarb* 116-14-3.................................. Tetrafluoroethylene 116-15-4.................................. Hexafluoropropylene 117-84-0.................................. Dioctyl phthalate 118-52-5.................................. 1,3-Dichloro-5,5- dimethylhydantoin 120-82-1.................................. 1,2,4-Trichlorobenzene 121-75-5.................................. Malathion 122-14-5.................................. Fenitrothion 123-31-9.................................. Hydroquinone 123-38-6.................................. Propionaldehyde* 123-86-4.................................. n-Butyl acetate* 124-40-3.................................. Dimethyl amine* 124-63-0.................................. Methanesulfonyl chloride 124-65-2.................................. Sodium cacodylate 129-00-0.................................. Pyrene 131-11-3.................................. Dimethyl phthalate 140-88-5.................................. Ethyl acrylate* 141-32-2.................................. Butylacrylate* 141-43-5.................................. Monoethanolamine 141-59-3.................................. t-Octyl mercaptan 141-66-2.................................. Dicrotophos 141-78-6.................................. Ethyl acetate* 143-33-9.................................. Sodium cyanide* 144-62-7.................................. Oxalic acid 149-74-6.................................. Dichloromethylphenyl silane 150-76-5.................................. p-Methoxyphenol 151-38-2.................................. Methoxyethyl mercury* 207-08-9.................................. Benzo(k)fluoranthene 218-01-9.................................. Chrysene 287-92-3.................................. Cyclopentane 297-78-9.................................. Isobenzan 298-00-0.................................. Methyl parathion* 298-02-2.................................. Phorate* 298-04-4.................................. Disulfoton* 300-62-9.................................. Amphetamine 333-41-5.................................. Diazinon 334-88-3.................................. Diazomethane* 353-50-4.................................. Carbonyl fluoride* 354-32-5.................................. Trifluoroacetyl chloride 371-62-0.................................. Ethylene fluorohydrin 382-21-8.................................. Perfluoroisobutylenene 453-18-9.................................. Methyl fluoroacetate* 460-19-5.................................. Cyanogen* 463-51-4.................................. Ketene* 463-58-1.................................. Carbonyl sulfide* 463-71-8.................................. Thiophosgene 503-38-8.................................. Diphosgene 506-68-3.................................. Cyanogen bromide* 506-78-5.................................. Cyanogen iodide 506-96-7.................................. Acetyl bromide 534-52-1.................................. 4,6-Dinitro-o-cresol 538-07-8.................................. Bis(2-chloroethyl)ethylamine 541-25-3.................................. Lewisite 541-41-3.................................. Ethyl chloroformate* 542-88-1.................................. bis-Chloromethyl ether* 543-27-1.................................. i-Butyl chloroformate 555-77-1.................................. Tris(2-chloroethyl)amine (N- Mustard) 556-61-6.................................. Methyl isothiocyanate 556-64-9.................................. Methyl thiocyanate* 563-12-2.................................. Ethion 578-94-9.................................. Adamsite 592-34-7.................................. n-Butyl chloroformate 593-53-3.................................. Methyl fluoride 593-89-5.................................. Methyl dichloroarsine 598-14-1.................................. Ethyl dichloroarsine 598-31-2.................................. Bromoacetone 622-44-6.................................. Phenyl carbylamine chloride 624-92-0.................................. Dimethyl disulfide* 625-55-8.................................. Isopropyl formate 627-44-1.................................. Diethyl mercury 640-19-7.................................. Fluoroacetamide 646-06-0.................................. Diulane 674-82-8.................................. Diketene* 675-14-9.................................. Cyanuric fluoride 676-83-5.................................. Methyl phosphonous dichloride 676-97-1.................................. Methyl phosphonic dichloride 681-84-5.................................. Tetamethoxysilane 684-16-2.................................. Hexafluoroacetone* 696-28-6.................................. Phenyl dichloroarsine 732-11-6.................................. Phosmet 757-58-4.................................. Hexaethyl tetraphosphate 813-78-5.................................. Dimethyl phosphate 919-86-8.................................. Demeton S-methyl 920-46-7.................................. Methacryloyl chloride 944-22-9.................................. Fonofos* 950-37-8.................................. Methidathion* 993-00-0.................................. Methyl chlorosilane* 993-13-5.................................. Methylphosphonic acid 993-43-1.................................. Ethylphosphonodithioicdichlo ride 999-81-5.................................. Clormequat chloride 1024-57-3................................. Heptachlor epoxide 1120-71-4................................. 1,3-Propane sultone 1303-28-2................................. Arsenic pentoxide 1306-02-1................................. Lewisite oxide 1314-84-7................................. Zinc phosphide 1319-77-3................................. Cresol* 1327-53-3................................. Arsenic trioxide* 1336-36-3................................. Polychlorinated biphenyl 1341-24-8................................. Chloroacetophenone* 1341-49-7................................. Ammonium bifluoride 1397-94-0................................. Antimycin A 1498-40-4................................. Ethylphosphonous dichloride 1498-51-7................................. Ethylphosphorodichloridate 1558-25-4................................. Chloromethyl (trichloro) silane 1563-66-2................................. Carbofuran* 1582-09-8................................. Trifluralin 1609-86-5................................. t-Butyl isocyanate 1634-04-4................................. Methyl t-butyl ether* 1675-54-3................................. Bisphenol A diglycidyl ether 1737-93-5................................. 3,5-Dichloro-2,4,5- trifluoropyridine 1746-01-6................................. 2,3,7,8-Tetrachlorodibenzo-p- dioxin* 1832-54-8................................. Isopropyl methyl phosphonic acid 1873-29-6................................. Isobutyl isocyanate 1910-42-5................................. Paraquat dichloride* 2032-65-7................................. Methiocarb 2231-57-4................................. Thiocarbazide 2487-90-3................................. Trimethoxysilane 2524-03-0................................. Dimethyl phosphorochloridothioate 2696-92-6................................. Nitrosyl chloride* 2698-41-1................................. o-Chlorobenzylidene malononitrile* 2699-79-8................................. Sulfuryl fluoride* 2937-50-0................................. Allylchloroformate 2941-64-2................................. Ethyl chlorothioformate 3048-64-4................................. Vinyl norbornene 3173-53-3................................. Cyclohexyl isocyanate* 3282-30-2................................. Trimethylacetyl chloride 3689-24-5................................. Tetraethyl dithiopyrophosphate (Sulfotep)* 3691-35-8................................. Chlorophacinone 4098-71-9................................. Isophorone diisocyanate 4109-96-0................................. Dichlorosilane 4300-97-4................................. Chloropivaloyl chloride 4418-66-0................................. Phenol, 2,2'-thiobis(4- chloro-6-methyl-) 5332-73-0................................. 3-Methoxypropyl amine 5798-79-8................................. Bromobenzyl cyanide 6427-21-0................................. Methoxymethyl isocyanate 6581-06-2................................. 3-Quinuclidinyl benzilate 6923-22-4................................. Monocrotophos* 7439-92-1................................. Lead & compounds including lead phosphate* 7439-96-5................................. Manganese & compounds 7439-97-6................................. Mercury & compounds including methyl mercury* 7440-02-0................................. Nickel and compounds* 7440-38-2................................. Arsenic & compounds* 7440-39-3................................. Barium & compounds 7440-41-7................................. Beryllium & compounds* 7440-43-9................................. Cadmium & compounds* 7440-48-4................................. Cobalt & compounds 7440-50-8................................. Copper & compounds 7440-62-2................................. Vanadium & compounds 7440-66-6................................. Zinc & compounds 7446-18-6................................. Thallium sulfate* 7446-70-0................................. Aluminum chloride 7521-80-4................................. Butyltrichlorosilane 7550-45-0................................. Titanium tetrachloride* 7580-67-8................................. Lithium hydride 7616-94-6................................. Perchloryl fluoride 7631-89-2................................. Sodium arsenate 7647-19-0................................. Phosphorus pentafluoride* 7664-38-2................................. Phosphoric acid* 7705-07-9................................. Titanium chloride 7719-09-7................................. Thionyl chloride* 7722-84-1................................. Hydrogen peroxide (concentration greater than 52%)* 7723-14-0................................. Phosphorus 7727-15-3................................. Aluminum bromide 7738-94-5................................. Chromic acid 7782-65-2................................. Germane 7782-68-5................................. Iodic acid 7783-07-5................................. Hydrogen selenide* 7783-41-7................................. Oxygen difluoride* 7783-54-2................................. Nitrogen trifluoride* 7783-61-1................................. Silicon tetrafluoride* 7783-70-2................................. Antimony pentafluoride 7783-71-3................................. Tantalum V fluoride 7783-79-1................................. Selenium hexafluoride* 7783-80-4................................. Tellurium hexafluoride* 7783-82-6................................. Tungsten hexafluoride 7784-46-5................................. Sodium arsenite* 7786-34-7................................. Mevinphos* 7787-71-5................................. Bromine trifluoride* 7789-21-1................................. Fluorosulfonic acid 7789-30-2................................. Bromine pentafluoride* 7789-59-5................................. Phosphorus oxybromide 7789-69-7................................. Phosphorus pentabromide 7789-75-5................................. Calcium fluoride 7790-94-5................................. Chlorosulfonic acid* 7791-23-3................................. Selenium oxychloride 7791-25-5................................. Sulfuryl chloride* 7803-49-8................................. Hydroxylamine* 7803-52-3................................. Stibine (antimony hydride)* 7803-62-5................................. Silane* 8001-35-2................................. Camphechlor 8006-61-9................................. Gasoline* 10025-67-9................................ Disulfur dichloride 10025-73-7................................ Chromic chloride 10026-13-8................................ Phosphorus pentachloride 10028-15-6................................ Ozone* 10034-85-2................................ Hydrogen iodide* 10035-10-6................................ Hydrogen bromide* 10265-92-6................................ Methamidophos* 10294-33-4................................ Boron tribromide* 10544-72-6................................ Nitrogen tetroxide 10544-73-7................................ Nitrogen trioxide 10545-99-0................................ Sulfur dichloride* 11099-02-8................................ Nickel oxide* 12002-03-8................................ Copper acetoarsenite* 12108-13-3................................ Manganese, tricarbonyl methylcyclopentadienyl 13071-79-9................................ Terbufos* 13194-48-4................................ Ethoprophos 13470-08-1................................ Titanium III fluoride 13637-63-3................................ Chlorine pentafluoride* 13863-41-7................................ Bromine chloride* 16752-77-5................................ Methomyl* 17462-58-7................................ iso-Butyl chloroformate 19624-22-7................................ Pentaborane* 20816-12-0................................ Osmium tetroxide* 20859-73-8................................ Aluminum phosphide* 22224-92-6................................ Fenamiphos 22967-92-6................................ Methyl mercury 23135-22-0................................ Oxamyl 23422-53-9................................ Formetanate hydrochloride 25321-14-6................................ Dinitrotoluene 25321-22-6................................ Dichlorobenzene 26419-73-8................................ Tirpate 27137-85-5................................ Trichloro (dichlorophenyl) silane 28772-56-7................................ Bromodiolone 30674-80-7................................ Methacryloyloxyethyl isocyanate 32315-10-9................................ Triphosgene

Magnetic Bubble Memory

Magnetic Bubble Memory Magnetic bubble memory is a non-volatile data storage medium invented at Bell Labs in 1967. Bubble memory uses a thin magnetic film on a garnet substrate, which forms cylindrical domains when constricted under a magnetic field. These domains, or bubbles, each store one bit of data. The bubbles are created by a generator signal, pushed around the film in racetrack-like loops, and eventually detected by a sense amplifier. Unlike semiconductor memories, bubble memory is sequential access, rather than random access. Conceptually, it is like a tiny magnetic diskette and drive, but with no moving parts. Instead of the disk moving, the bits move. Bubble memory was a promising technology that was positioned to replace all other forms of memory, but was quickly outpaced by semiconductor memory (speed and cost) and hard disk drives (capacity and cost). The computer industry was already shaped around a well-established split between fast, small-capacity main memory and slower large-capacity storage, and bubble memory was squeezed out in both categories as a costlier, inferior alternative. Bubble memory may still be occasionally used in some military and industrial applications, where extreme ruggedness and nonvolatility are a requirement. Bubble memory is inherently radiation-hardened: it can withstand the photoelectric effects of a nuclear event, when implemented with specialized nonstop logic circuits which prevent partial loop rotation. Former manufacturers of magnetic bubble memory include Hitachi, Intel, Motorola, Rockwell and Texas Instruments. Recently, IBM has re-branded the bubble memory concept as 'racetrack' memory, a sort of nano-scale bubble memory which uses an array of tiny wire loops to carry the magnetic domains. Intel 7xxx Series Devices included in this entry: Intel 7110-1 bubble memory (20-pin ceramic LCC; pictured in thumbnail) Intel D7220-1 bubble memory controller (40-pin ceramic sandwich DIP) Intel D7230 current pulse generator (22-pin ceramic sandwich DIP) Intel D7242 sense amplifier (20-pin ceramic sandwich DIP) Intel D7250 coil pre-drive (16-pin ceramic sandwich DIP) The Intel 7110 is a high density 1-megabit bubble memory device. The 7110 has 256 data loops of 4096 bits each, arranged as 2048 512-bit pages. The 7110 has separate input and output tracks, as well as other advanced architectural features. The example pictured here is a 7110-1, the first incarnation of the 7110, with a 20-pin leadless carrier and medium ambient temperature tolerance. 'A' variants (7110A-1, 7110A-4, 7110A-5) have standard tinned through-hole pins. Variants with the -4 suffix (7110-4, 7110A-4) have low temperature tolerance, while -5 variants (7110-5, 7110A-5) have high temperature tolerance. Additionally, there are 'AZ' types with through-hole pins (7110AZ-1, 7110AZ-4) whose performance characteristics are currently unknown. It should also be noted that some early documentation refers to the 7110-4 as the 7110-0 or simply 7110 with no suffix, and the 7110-5 is listed as the 7110-2. It is unknown whether this abandoned numbering scheme ever made it to production. Intel subsequently developed the 7114-1, a hard-to-find 4-megabit module in a 20-pin package with tinned through-hole pins. Intel Magnetic Bubble Storage Data Catalog BPK 72 Prototype Kit Datasheet BPK 72 Prototype Kit User's Manual Intel Solutions Bubble Memory Application Note 7110 1-Megabit Bubble Memory Datasheet 7220-1 Bubble Memory Controller Datasheet 7230 Current Pulse Generator Datasheet 7242 Dual Formatter/Sense Amplifier Datasheet 7250 Coil Pre-Drive Datasheet 7254 Quad VMOS Drive Transistors Datasheet [View Detail] Sharp CE-100B The CE-100B is a removable bubble memory cartridge designed for use with the Sharp PC-5000 portable computer. The CE-100B is basically a Hitachi 1-megabit bubble memory module with a few extra layers of armor to help it withstand the harsh environment of regular handling by filthy humans. Nuclear blast? No problem. Secretary's purse? Better add another layer of metal, and a plastic carrying case. We were unable to open the cartridge without cosmetically damaging it, so you'll just have to imagine what a Hitachi MBM looks like. They were made in Japan in the 1980s, so imagine an Intel 7110 only boxier and more cheaply constructed. [View Detail] Texas Instruments TIB S0004-3 2200046-0203 Later variant of the original Texas Instruments TIB0203 92,304-bit bubble memory. Exact specifications are unknown. Like Intel's devices, TI bubble memory uses a major-minor loop architecture. TIB0203 Bubble Memory (Decode Systems article) [View Detail]

SRAM Modules Information

SRAM Modules Information Show all SRAM Modules Manufacturers Find by Specification: Form Factor: SO DIMM Card Other Capacity: Less than 0.87 MB 0.87 to 6 MB 6 to 27 MB 27 to 154 MB 154 MB and up Clock Speed: 100 to 100 MHz 133 to 133 MHz 200 to 200 MHz 266 to 266 MHz More Specifications >> How to Select SRAM Modules Image Credit: Digi-Key | 3Sixty Group | Centon SRAM memory modules use static random access memory (SRAM), a type of memory that is faster, more reliable, and more expensive than dynamic random access memory (DRAM). Unlike DRAM computer memory modules, SRAM memory modules do not need to be refreshed in order to prevent data loss; however, SRAM requires more power than DRAM. Typically, SRAM memory modules are used in small, central processing unit (CPU) applications. SRM memory modules are also used in a system cache, as video memory, or other small memory systems such as a frame buffer for a display adapter. SRAM modules are sold in a wide variety of configurations, and vary according to speed, pin configuration, and power consumption characteristics. SRAM Types SRAM modules can be used to upgrade the system cache in an older computer to store larger amounts of data, or to allow the microprocessor to access other memory sources than the hard disk, making high speed access possible. There are different types of SRAM modules, including: • Asynchronous static RAM- Asynchronous RAM was the first type of RAM, and is usually used to offer an inexpensive memory or speed upgrade to older machines. • Synchronous burst static RAM-Synchronous burst static RAM is expensive but very fast. • Pipeline-burst static RAM (PBSRAM)- Pipeline-burst static RAM is the most commonly used static RAM today. After the first round of access, it is designed to allow subsequent access cycles to require fewer machine cycles, allowing for a greater throughput of data. SRAM Applications SRAM memory modules are qualified as volatile memory, meaning that they can retain the information stored only as long as the power is turned on. Once the power is turned off, the SRAM memory modules lose the data stored there. Non-volatile memory such as a Flash can retain the information stored on them without power. Flash memory is very useful in electronic devices that are turned on and off frequently and yet still need to retain the information stored on them, such as digital cameras and video recorders. A digital camera memory chip can store a large amount of data over time, as well as remember settings and other programmable functions. Flash memory devices also include flash drives, thumb drives, or universal serial bus (USB) key drives. A USB memory chip is typically a circuit board with a Flash memory chip wired to a USB connector encased in a plastic housing.

SRAM Memory Chips Information

SRAM Memory Chips Information Show all Manufacturers SRAM Memory Chips Information Static random access memory (SRAM) chips are dual-transistor memory cells that require a constant supply of power in order to retain their content. Each SRAM bit is a flip-flop circuit made of cross-coupled inverters. The activation of transistors controls the flow of current from one side to the other. The transistors are connected so that one only transistor is in or out at any time. When power is received, all SRAM cells are in a logical state of 1 (ON). Subsequent data writing changes some of the cells to a logical stage of 0 (OFF). This state is maintained until the next write operation, or when power is removed. Because they use multiple transistors, SRAM memory chips are more expensive and require more power than DRAM memory chips; however, because they do not need to be constantly refreshed, SRAM memory chips are faster and more reliable. Common applications for SRAM memory chips include system caches and video memory. Specifications Important specifications for SRAM memory chips include density, number of words, bits per word, access time, cycle time, data rate, supply voltage, data retention voltage, and data retention current. Density is the capacity of the chip in bits. The number of words equals the number of rows, each of which stores a memory word and connects to a word line for addressing purposes. The bits per word are the number of columns, each of which connects to a sense/write circuit. Supply voltages range from - 5 V to 5 V and include many intermediate voltages. Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the central processing unit (CPU) sends a request to memory and ends when the CPU receives the data requested. Cycle time is the time required to both perform a single read or write operation and reset the internal circuitry so another operation can begin. Data retention voltage and data retention current are, respectively, the minimum voltage and minimum current that SRAM memory cells must maintain in order to preserve stored data. Measured in hertz (Hz), data rate is the number of bits per second that can be moved internally. Selecting SRAM Memory Chips Selecting SRAM memory chips requires an analysis of logic families. Transistor-transistor logic (TTL) and related technologies such as Fairchild advanced Schottky TTL (FAST) use transistors as digital switches. By contrast, emitter coupled logic (ECL) uses transistors to steer current through gates that compute logical functions. Another logic family, complementary metal-oxide semiconductor (CMOS) uses a combination of p-type and n-type metal-oxide-semiconductor field effect transistors (MOSFET) to implement logic gates and other digital circuits. Logic families for SRAM memory chips include cross-bar switch technology (CBT), gallium arsenide (GaAs), integrated injection logic (I2L) and silicon on sapphire (SOS). Gunning with transceiver logic (GTL) and gunning with transceiver logic plus (GTLP) are also available. IC Package Types SRAM memory chips are available in a variety of IC package types and with different numbers of pins. Basic IC package types for SRAM memory chips include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available. For example, BGA variants include plastic-ball grid array (PBGA) and tape-ball grid array (TBGA). QFP variants include low-profile quad flat package (LQFP) and thin quad flat package (TQFP). DIPs are available in either ceramic (CDIP) or plastic (PDIP). Other IC package types include small outline package (SOP), thin small outline package (TSOP), and shrink small outline package (SSOP).

Memory Chips Information

Memory Chips Information Show all Memory Chips Manufacturers Find by Specification: Memory Category: DRAM SRAM FIFO Flash PROM Density: At least 9 kbits At least 519 kbits At least 4,820 kbits At least 1.66E+5 kbits Number of Words: Less than 4 k 4 to 393 k 393 to 4,096 k 4,096 to 32,768 k 32,768 k and up More Specifications >> Memory chips are internal storage areas in computers. Although the term “memory chip” commonly refers to a computer's random access memory (RAM), this product area includes many different types of electronic data storage. Computer memory stores data electronically in cells. Without memory chips, a computer could not read programs or retain data. The two most common types of memory chips are DRAM chips and SRAM chips. Dynamic random access memory (DRAM) is single-transistor memory cell that requires regular refreshes. DRAM chips consist of small capacitors for each bit of memory. Since capacitors do not hold a charge indefinitely, DRAM memory chips must be constantly refreshed to avoid losing its contents. In addition, the process of reading the contents of the memory are destructive, which means that extra time must be spent restoring the contents of memory addresses. Consequently, DRAM is slower than SRAM. Static random access memory (SRAM) is a volatile memory cell that does not require updates or periodic refresh cycles to keep the memory content intact. Other types of memory chips use FIFO or Flash. First-in, first-out (FIFO) memory is used in buffering applications between devices that operate at different speeds. Flash memory is a form of electrically erasable, programmable, read-only memory (EEPROM) that can be erased and reprogrammed in blocks, rather than one byte at a time. Flash memory does not need a constant power supply to retain data and offers fast access, low power consumption, and relative immunity to shock or vibration. Flash memory chips have an approximant lifespan of 100,000 write cycles. Consequently, Flash is not suitable to be the main memory of a computer. Instead, Flash is used in digital cameras, cell phones, pagers, scanners, laptops, and video game memory cards. PROM, EPROM, and EEPROM memory chips are also available. Programmable read-only memory (PROM) can only be written once. EPROM stands for erasable programmable read-only memory. These PROM memory chips can be erased through exposure to ultraviolet (UV) light and then reprogrammed. EEPROM memory chips are similar to EPROM chips; however, EEPROM can be erased electronically. Other, unlisted types of memory chips are also available. Power specifications for memory chips include the supply voltage, the maximum and minimum operating currents, standby current, and power dissipation. Specialized specifications for memory chips refer to access time, cycle time, data retention, endurance, and operating temperature. Additional specifications for memory chips may also be available.

FLASH Memory Chips Information

FLASH Memory Chips Information Show all FLASH Memory Chips Manufacturers Find by Specification: Density: At least 1,024 kbits At least 10,000 kbits At least 2.56E+5 kbits At least 4.00E+6 kbits Number of Words: Less than 204 k 204 to 622 k 622 to 1,810 k 1,810 to 91,750 k 91,750 k and up Bits per Word: 4,224 to 4,224 bits More Specifications >> Flash memory chips are electrically erasable, programmable, read-only memory (EEPROM) chips that can be erased and reprogrammed in blocks instead of one byte at a time. Because they are non-volatile, Flash memory chips do not need a constant power supply to retain their data. Flash memory chips offer extremely fast access times, low power consumption, and relative immunity to severe shock or vibration. They have a lifespan of approximately 100,000 write cycles - a fact that makes Flash unsuitable for use as computer main memory. Typically, Flash memory chips are used in portable or compact devices such as digital cameras, cell phones, pagers, and scanners. Flash memory chips are also used as solid-state disks in laptops and as memory cards for video game consoles. Flash memory chips vary in terms of density, boot block size, number of words, bits per word, gate technology, and special features. Density is the capacity of the chip in bits. Boot block size is a secured block used to store boot codes. The number of words equals the number of rows, each of which stores a memory word and connects to a word line for addressing purposes. The bits per word are the number of columns, each of which connects to a sense / write circuit. Some Flash memory chips support NAND or serial access gate technology. Other devices support NOR or random access gate technology. In terms of special features, Flash memory chips can be read either in bursts of bits or page-by-page. Flash memory chips that provide read-while-write (RWW) operation can be read and written to at the same time. Selecting Flash memory chips requires an analysis of performance specifications such as access time, data retention, endurance, supply voltage, and operating temperature. Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the CPU sends a request to memory and ends when the CPU receives the data requested. Data retention is the number of years that chips can retain data without reloading. Endurance is the maximum number of read/write cycles that chips can support. Supply voltages range from - 5 V to 5 V and include intermediate voltages such as -4.5 V, -3.3 V, -3 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3 V, 3.3 V, and 3.6 V. Some Flash memory chips support a specific temperature range and feature mechanical and electrical specifications that are suitable for commercial or industrial applications. Other Flash memory chips meet screening levels for military specifications (MIL-SPEC). Selecting Flash memory chips requires an analysis of logic families. Transistor-transistor logic (TTL) and related technologies such as Fairchild advanced Schottky TTL (FAST) use transistors as digital switches. By contrast, emitter coupled logic (ECL) uses transistors to steer current through gates that compute logical functions. Another logic family, complementary metal-oxide semiconductor (CMOS) uses a combination of p-type and n-type metal-oxide-semiconductor field effect transistors (MOSFET) to implement logic gates and other digital circuits. Logic families for Flash memory chips include cross-bar switch technology (CBT), gallium arsenide (GaAs), integrated injection logic (I2L) and silicon on sapphire (SOS). Gunning transceiver logic (GTL) and gunning transceiver logic plus (GTLP) are also available. Flash memory chips are available in a variety of IC package types and with different numbers of pins and flip-flops. Basic IC package types include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available. For example, BGA variants include plastic-ball grid array (PBGA) and tape-ball grid array (TBGA). QFP variants include low-profile quad flat package (LQFP) and thin quad flat package (TQFP). DIPs are available in either ceramic (CDIP) or plastic (PDIP). Other IC package types include small outline package (SOP), thin small outline package (TSOP), and shrink small outline package (SSOP).

FIFO Memory Information

FIFO Memory Information Show all FIFO Memory Manufacturers Find by Specification: Communication Type: Synchronous Asynchronous Production Status: Discontinued Logic Family: Transistor-Transistor Logic (TTL) More Specifications >> First-in, first-out (FIFO) memory chips are used in buffering applications between devices that operate at different speeds or in applications where data must be stored temporarily for further processing. Typically, this type of buffering is used to increase bandwidth and to prevent data loss during high-speed communications. As the term FIFO implies, data is released from the buffer in the order of its arrival. Some FIFO memory reads with one clock and writes with another simultaneously. Synchronous operations require a clock, but asynchronous operations do not. Flow control generates full and empty signals so that inputs do not overwrite the contents of the buffer. Depending on the device, FIFO memory can be unidirectional or bidirectional. FIFO memory can also include parallel inputs and outputs as well as programmable flags. FIFO memory varies in terms of density, number of words, bits per word, supply voltage, and operating temperature. The density is the capacity of the chip in bits. The number of words equals the number of rows, each of which stores a memory word and connects to a word line for addressing purposes. Bits per word are the number of columns, each of which connects to a sense/write circuit. Supply voltages range from - 5 V to 5 V and include intermediate voltages such as -4.5 V, -3.3 V, -3 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3 V, 3.3 V, and 3.6 V. Some FIFO memory chips support a specific temperature range and feature mechanical and electrical specifications that are suitable for commercial or industrial applications. Other FIFO memory chips meet screening levels for military specifications (MIL-SPEC). Selecting FIFO memory requires an analysis of performance specifications such as access time, data rate, data setup time, and data hold time. Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the CPU sends a request to memory and ends when the CPU receives the data requested. The data rate or transfer speed is the number of bits per second in hertz (Hz) that can be moved internally in the chip. The data setup time is the minimum time interval required for logic levels to be maintained constantly in the input lines prior to the triggering edge of the clock pulse in order for the levels to be reliably clocked into the memory. The data hold time is the minimum time interval required for logic levels to remain on the inputs after the triggering edge of the clock pulse in order to be reliably clocked into the chip. FIFO memory chips vary in terms of logic family and IC package type. Common logic families include standard, fast, high-speed and advanced CMOS; emitter coupled logic (ECL); TTL and Fairchild advanced Schottky TTL (FAST); gunning technology (GTL); and crossbar switch technology (CBT). Common package types include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available for FIFO chips. Common packaging materials include plastic, ceramic, metal, and glass.

EEPROM Information

EEPROM Information Show all EEPROM Manufacturers Find by Specification: Density: At least 2 kbits At least 25 kbits At least 410 kbits At least 3,600 kbits Number of Words: Less than 1 k 1 to 20 k 20 to 700 k 700 to 9,800 k 9,800 k and up Bits per Word: 32 to 32 bits More Specifications >> Electrically erasable programmable read-only memory (EEPROM) chips are similar to PROM devices, but require only electricity to be erased. Architecture or status, performance, power characteristics, and packaging information are all important parameters to consider when searching for EEPROM memory chips. Architecture or status specifications that are important to consider when searching for EEPROM memory chips include density, number of words, bits per word, bus type, and production status. Density is the capacity of the memory chip expressed in bits. Number of words refers to the number of "rows" in the organization of the memory chip. Each row stores a memory word and connects to a word line (one line of the memory bus) for addressing purposes. Bits per word refer to the number of "columns" in the organization of the memory chip. Each column connects to a sense / write circuit (a bit), which connects to data input/output lines of the chip. Common choices for bus type include parallel, serial, serial-1wire, serial-2 wire, serial-3 wire, I2C, Microwire, SPI, and serial-uPort. Production status can be active, discontinued or new. Active EEPROM memory chips are available and are currently being manufactured. Discontinued EEPROM memory chips are no longer available from the manufacturer, but may still be found in the supply chain. New devices are either just hitting the market, or are soon to be, as announced by the manufacturer. Common performance specifications for EEPROM memory chips include data rate, access time, data retention, endurance, and logic family. Data rate is the transfer speed in hertz. This is the number of bits per second that can be moved internally in the chip. Access time is a measurement of time in nanoseconds (ns) used to indicate the speed of memory. Access time is a cycle that begins the moment the CPU sends a request to memory and ends the moment the CPU receives the data it requested. Specifically, for a synchronous device it is the time, usually in ns, from a clock edge to when data is available at the output of a device. For an asynchronous device it is the time from the initiation of the read cycle to when the data output is available. Data retention is the time (in years) that the memory chip can retain the data without reloading. Endurance is the maximum number of write / read cycles that the chip can support. Common choices for logic family include L, S, H, LS, AS, ALS, FAST, HC, HCT, AHC, AHCT, FCT, AC, ACT, AQC, ABT, ABTE, ABTH, BCT, BTL, CBT, FB, GTL, GTLP, ALB, LV, LVC, LVCH, ALVC, LVT, LVTZ, ALVCH, LCX, VCX, CBTLV, CMOS (4000), ECL, and TTL. Important power characteristics specifications to consider when selecting EEPROM memory chips include supply voltage, power dissipation, operating current, and standby current. Common choices for supply voltage include –5 V, -4.5 V, -3.3 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 2.7 V, 3 V, 3.3 V, 3.6 V, and 5 V. The power dissipation is the total power consumption of the device. It is generally expressed in watts or milliwatts. The operating current is the minimum current needed for active chip operation. The standby current is the minimum current needed for the operation of the chip while is inactive. Common package information for EEPROM memory chips includes pin count, screening level, package type, package material, and operating temperature.

EPROM Information

EPROM Information Show all EPROM Manufacturers Find by Specification: EPROM Type: EPROM Density: At least 22 kbits At least 261 kbits At least 1,219 kbits At least 6,438 kbits Number of Words: Less than 44 k 44 to 112 k 112 to 300 k 300 to 800 k 800 k and up More Specifications >> Erasable programmable read-only memory (EPROM) chips are programmable, reusable computer chips that can be erased using ultraviolet light and reprogrammed with a PROM programmer or PROM burner. Programming or burning an EPROM chip injects electrons with an elevated voltage into the floating gate a field-effect transistor, trapping the electrons and forcing a reading of zero. Erasing an EPROM chip bombards the chip with ultraviolet radiation through a quartz window to provide the trapped electrons with enough energy to escape the floating gate. To prevent slow erasure over a period of years from sunlight and fluorescent lights, the quartz window is covered with an opaque label during normal use. EPROM is used widely in personal computers because it enables manufacturers to change the contents of programmable read-only memory before the computer is shipped. Since EPROM chips do not require power to retain their data, they are commonly used to store BIOS information and basic software for modems, video cards, and other peripherals. Flash EPROM or FEPROM incorporates FLASH technology and is available from some chip manufacturers. Other architectural considerations include density, which is the capacity of the memory chip expressed in bits, as well as the number of rows and columns. With EPROM, each row stores a memory word and connects to a word line for addressing purposes. The number of columns equals the bits per word. Each column connects to a sense / write circuit. Selecting EPROM chips requires the selection of a serial or parallel data bus and the analysis of several performance specifications. Operating current is the minimum current needed for active chip operation. Standby current is the minimum current needed during inactivity. Power dissipation, which is generally expressed in watts or milliwatts, is the total power consumption of the device. Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the CPU sends a request to memory and ends when the CPU receives the data requested. Some EPROM chips support a specific temperature range and feature mechanical and electrical specifications that are suitable for commercial or industrial applications. Other EPROM chips meet screening levels for military specifications (MIL-SPEC). EPROM chips vary in terms of supply voltage, logic family, and package type. Common logic families include standard, fast, high-speed and advanced CMOS; emitter coupled logic (ECL); TTL and Fairchild advanced Schottky TTL (FAST); gunning technology; and crossbar switch technology (CBT). Common package types include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available for EPROM chips. Common packaging materials include plastic, ceramic, metal, and glass.

SRAM Memory Chips Information

SRAM Memory Chips Information Show all Manufacturers SRAM Memory Chips Information Static random access memory (SRAM) chips are dual-transistor memory cells that require a constant supply of power in order to retain their content. Each SRAM bit is a flip-flop circuit made of cross-coupled inverters. The activation of transistors controls the flow of current from one side to the other. The transistors are connected so that one only transistor is in or out at any time. When power is received, all SRAM cells are in a logical state of 1 (ON). Subsequent data writing changes some of the cells to a logical stage of 0 (OFF). This state is maintained until the next write operation, or when power is removed. Because they use multiple transistors, SRAM memory chips are more expensive and require more power than DRAM memory chips; however, because they do not need to be constantly refreshed, SRAM memory chips are faster and more reliable. Common applications for SRAM memory chips include system caches and video memory. Specifications Important specifications for SRAM memory chips include density, number of words, bits per word, access time, cycle time, data rate, supply voltage, data retention voltage, and data retention current. Density is the capacity of the chip in bits. The number of words equals the number of rows, each of which stores a memory word and connects to a word line for addressing purposes. The bits per word are the number of columns, each of which connects to a sense/write circuit. Supply voltages range from - 5 V to 5 V and include many intermediate voltages. Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the central processing unit (CPU) sends a request to memory and ends when the CPU receives the data requested. Cycle time is the time required to both perform a single read or write operation and reset the internal circuitry so another operation can begin. Data retention voltage and data retention current are, respectively, the minimum voltage and minimum current that SRAM memory cells must maintain in order to preserve stored data. Measured in hertz (Hz), data rate is the number of bits per second that can be moved internally. Selecting SRAM Memory Chips Selecting SRAM memory chips requires an analysis of logic families. Transistor-transistor logic (TTL) and related technologies such as Fairchild advanced Schottky TTL (FAST) use transistors as digital switches. By contrast, emitter coupled logic (ECL) uses transistors to steer current through gates that compute logical functions. Another logic family, complementary metal-oxide semiconductor (CMOS) uses a combination of p-type and n-type metal-oxide-semiconductor field effect transistors (MOSFET) to implement logic gates and other digital circuits. Logic families for SRAM memory chips include cross-bar switch technology (CBT), gallium arsenide (GaAs), integrated injection logic (I2L) and silicon on sapphire (SOS). Gunning with transceiver logic (GTL) and gunning with transceiver logic plus (GTLP) are also available. IC Package Types SRAM memory chips are available in a variety of IC package types and with different numbers of pins. Basic IC package types for SRAM memory chips include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available. For example, BGA variants include plastic-ball grid array (PBGA) and tape-ball grid array (TBGA). QFP variants include low-profile quad flat package (LQFP) and thin quad flat package (TQFP). DIPs are available in either ceramic (CDIP) or plastic (PDIP). Other IC package types include small outline package (SOP), thin small outline package (TSOP), and shrink small outline package (SSOP).

FLASH Memory Technology: Considerations for Application Design

From Microchip Technology, Inc. Many times, choosing a FLASH memory device is driven by which manufacturer has the cheapest offering. Regardless of its use as a stand-alone device or as the program memory of a microcontroller, what is often overlooked are the many key design parameters, or the features that the memory may offer to the application. Endurance, data retention, temperature, operating voltage and frequency, and programming time all play significant roles in the reliability of the device. Selections based on cost alone may be penny-wise but dollarfoolish; the application may be the cheapest on the market but its overall quality can negatively impact the customer?s perception and therefore, their future purchases. Carefully balancing these factors can make the difference between an application that?s a long term superstar or a one hit wonder EPROM Erasable programmable read-only memory (EPROM) chips are programmable, reusable computer chips that can be erased using ultraviolet light and reprogrammed with a PROM programmer or PROM burner. Search by Specification | Learn more about EPROM EPROM Type: EPROM Density: At least 22 kbits At least 261 kbits At least 1,219 kbits At least 6,438 kbits Number of Words: Less than 44 k 44 to 112 k 112 to 300 k 300 to 800 k 800 k and up SRAM Memory Chips Static random access memory (SRAM) chips do not need to be refreshed like DRAM chips. This makes SRAM chips faster and more reliable. Learn more about SRAM Memory Chips Memory Chips Memory chips are internal storage areas in computers. Although the term "memory chip" commonly refers to a computer's random access memory (RAM), this product area includes many different types of electronic data storage. Computer memory stores data electronically in cells. Without memory chips, a computer could not read programs or retain data. Search by Specification | Learn more about Memory Chips EEPROM Electrically erasable programmable read-only memory (EEPROM) chips are similar to PROM devices, but require only electricity to be erased. Search by Specification | Learn more about EEPROM --------------------------------------------------------------------------------

Voltage to Frequency Converter Chips Information

Voltage-to-frequency converter chips provide a signal frequency output as a function of an analog input voltage. A voltage-to-frequency converter chip is widely used for applications where a temperature proportional output is required in a phase-locked loop. In a voltage to frequency converter circuit, an operational amplifier acts as an input to the voltage-to-frequency converter chip. The input current in the voltage to frequency circuit is directed to a NPN transistor to start its operation. Next, a 1mA current and full scale input voltage is fed to the voltage to frequency converter circuit. This voltage provides bias levels and starts charging current to the capacitor, which in turn generates low non-linear square wave frequency output. There are many types of voltage-to-frequency converter chips. Examples include an AD537 voltage to frequency conversion chip and an AD7740 voltage to frequency conversion chip. AD537 voltage-to-frequency converter chips are widely used as an accurate reference generator and a precision oscillator system. An AD7740 voltage to frequency converter chip is low cost, ultra-small frequency converter, used for isolation of high common-mode voltages. Other voltage-to-frequency converter chips are commonly available. There are several ways in which voltage-to-frequency converter chips function. A voltage-to-frequency converter chip works by supplying a full-scale voltage to the NPN transistor and then charging the integrated capacitor of the circuit. Low-voltage systems will in turn then generate signal frequency outputs in the form of square waves. An AD537 voltage to frequency conversion chip should have a voltage supply in the range of 5 to 36 volts and a linearity of +/-0.05% FS. In addition, an AD537 voltage to frequency conversion chip should have a thermometer output of 1mV/K and be fitted with a versatile input amplifier. An AD7740 operates from a single 3.0 V to 3.6 V or 4.75 V to 5.25 V supply and consumes typically 0.9 mA when the input is unbuffered. An AD7740 does not require external resistors and capacitors to set the output frequency. The maximum output frequency of an AD7740 is set by a crystal or a clock. Voltage-to-frequency converter chips are designed and manufactured to meet most industry specifications. Voltage-to-frequency converter chips are used in many applications. Voltage-to-frequency converter chips are widely used in two-wire data transmissions and in transducers. Voltage-to-frequency converter chips are also used in power sectors, electronics laboratories as oscillator circuits, and reference. Thesecchips are very usefull in computer data storage systems that utilize signals as codes for text, audio, and video data.