memory products - Al Kossow's Bitsavers

MK4501 (N, K)-65/80/1 0112/15/20READ MODEThe MK4501 initiates a Read Cycle (see Figure ~)on the falling edge of Read Enable control input (R),provided that the Empty Flag (EF) is not asserted.In the Read mode of operation, the MK4501 providesa fast access to data from 9 of 4608 locationsin the static storage array. The data is accessed ona FIFO basis indee,endent of any ongoing WRITEoperations. After R goes high, data outputs willreturn to a high impedance condition until the nextRead operation.In the event that all data has been read from theFIFO, the EF will go low, and further Read opera-tions will be inhibited ~ data outputs will remainin high impedance). EF will go high tWEF aftercompletion of a valid Write operation. EFwill again go low tAEF from the beginning a subsequentREAD operation, provided that a secondWRITE has not been completed ~e Figure 4B).Reads beginning tEFA after ELgoes highare valid. Reads begun after.-£F goes lowand more than t API before EF goes highare invalid Q9.nored). Reads beginning less thantAP I before EF goes high and less than tEFA latermayor may not occur (be valid) depending on internalflag status.FIGURE 3B. READ AND EMPTY FLAG TIMINGw..AC ELECTRICAL CHARACTERISTICS(O°C:s;TA:S; +70°C) (VCC = +5.0 volts ± 10%)SYM PARAMETER4501·65 4501·80tAC Read Cycle Time 80 100tA Access Time 65 80tAA Read Recovery Time 15 20APW Read Pulse Width 65 80tAL R Low to Low Z 0 0tov Data Valid from HighR 5 5tAHZ R High to High Z 25 25tAEF R Low to EF Low 60 75tEFA EF High to Valid Read 10 10tWEFW High to.EF High 60 75tAPI Read Protect Indeterminant 35 354501·10 4501·12 4501·15 4501·20MIN MAX MIN MAX MIN MAX MIN MAX MIN MAX MIN MAX UNITS NOTES120 140 175 235 ns100 120 150 200 ns 220 20 25 35 ns100 120 150 200 ns 10 0 0 0 ns 25 5 5 5 ns 225 35 50 60 ns 295 115 145 195 ns 210 10 10 10 ns 295 110 140 190 ns 235 35 35 35 ns 24/15400