1 - Al Kossow's Bitsavers

TMS4164, SMJ416465,536-811. DYNAMIC RANDOM-ACCESS MEMORYrefreshA refresh operation must be performed at least every four milliseconds to retain data. Since the output buffer is inthe high-impedance state unless CAS is applied, the RAS-only refresh sequence avoids any output during refresh.Strobing each of the 256 row addresses lAO through A 7) with RAS causes all bits in each row to be refreshed. CAScan remain high (inactive) for this refresh sequence to conserve power.page-modePage-mode operation allows effectively faster memory access by keeping the same row address and strobing successivecolumn addresses onto the chip. Thus, the time required to setup and strobe sequential row addresses forthe same page is eliminated. To extend beyond the 256 column locations on a single RAM, the row address and RASare applied to mUltiple 64K RAMs. CAS is then decoded to select the proper RAM.power-upAfter power-up, the power supply must remain at its steady-state value for 1 ms. In addition, RAS must remain highfor 100 p.s immediately prior to initialization. Initialization consists of performing eight RAS cycles before proper deviceoperation is achieved.logic symbol tAOA1A2A3A4A5A6A7RASCASViD15)~.;....---t 20D8/2100(7)(6)(12)(11)(10)(13)(9)(4)(15)(3)(2)....;..~--_t A,220RAM 64K X 1oA--6553523C22(14)AVt----- QC/)Q)(J->Q)c.....a..oC.C.::::J(J)> a..oEQ)~"Cc:CO~«a:(J-ECOc:>Ct This symbol is in accordance with IEEE Std 91/ANSI Y32.14 and recent decisions by IEEE and lEe. See explanation on page 10-1.ITEXASNSTRUMENlSPOST OFFICE BOX 225012 • DALLAS, TEXAS 752654-41