1 - Al Kossow's Bitsavers

lOGIC SYMBOLSWhen RAS goes low, it momentarily enables (through C20, I> indicates a dynamic input) the D inputs of the sevenaddress registers 7 through 13. When CAS goes low, it momentarily enables (through C21) the D inputs of the sevenaddress registers 0 through 6. The outputs of the address registers are the 14 internal address lines that select 1 of16,384 cells.5.3 REFRESHRAS4lREFRESH RowlWhen RAs goes low,row refresh starts. It ends when RAS goes high. Theother input signals required to carry out refreshing are not indicated bythe symbol.5.4 POWER DOWNRAS ~ 24 [PWR DWNlCAS ----1 G24 .CAS is AND'ed with RAs (through G24) so when RAS and CAS are bothhigh, the device is powered down.5.5WRITERASCASiND23C22By virtue of the AND relationship between CAS and iN (explicitly shown),when either one of these inputs goes low with the other one and RAs alreadylow (RAS is AND'ed by G23), the D input is momentarily enabled(through C22). In an "early-write" cycle it is W that goes low first; thiscauses the output to remain off as explained below.5.6READCAS--e.......,&.;~C21G24RAS --....... ~ G23iN ----I 23,21 D '24EN1----..... A\lIf you have questions on this Explanationof New Logic Symbols, please contact:F.A. Mann MS 49Texas Instruments IncorporatedP.O. Box 225012Dallas, Texas 75265Telephone (214) 995-2867QThe AND'ed result of RAS and iN (produced by G23) isclocked into a latch (through C21) at the instant CAS goeslow. This result will be a "1" if RAS is low and iN is high.The complement of CAS is shown to be AND'ed with theoutput of the latch (by G24 and 24). Therefore, as long asCAS stays low, the output is enabled. In the "early-write"cycle referred to above, a "0" was stored in the latch by Wbeing low when CAS went low, so the output remaineddisabled.IEEE Standards may be purchased from:Institute of Electrical and Electronics Engineers, Inc.345 East 47th StreetNew York, N.Y. 10017International Electrotechnical Commission (lEC)publications may be purchased from:American National Standards Institute,lnc.1430 BroadwayNew York, N.Y. 10018tn'0.cE>en(.)'0,o...I184TEXAS INSTRUMENTS 10-5INCORPORATEDPOST OFFICE BOX 225012 • DALLAS, TEXAS 75265