View mb81c4256-10 datasheet:

MB81C4256-10 IL08 ********** C-MOS 1M (262,144x4)-BIT DYNAMIC RAM - TOP VIEW - 6 DQ1 1 GND 20 A0 7 A1 8 1 DQ2 2 19 DQ4 A2 DQ1 9 2 A3 DQ2 11 18 WE 3 18 DQ3 A4 DQ3 12 19 A5 DQ4 13 RAS 4 17 CAS A6 14 A7 15 5 N.C. 16 OE A8 A0 6 15 A8 4 17 3 16 A1 7 14 A7 A0-8 ; ADDRESS INPUTS CAS ; COLUMN ADDRESS STROBE A2 8 13 A6 DQ1-4 ; DATA INPUTS/OUTPUTS OE ; OUTPUT ENABLE A3 9 12 A5 RAS ; ROW ADDRESS STROBE VDD WE ; WRITE ENABLE 10 11 A4 (+5V) SUBSTRATE BIAS 4 GEN. RAS CLOCK GEN. No1 17 WRITE 3 CAS CLOCK CLOCK WE GEN. No2 GEN. MODE CONTROL SERIAL ACCESS COUNTER DATA INPUT BUFFER ADDRESS COLUMN BUFFER DECODER 6-9,11-15 1,2,18,19 SENSE AMP. A0-A8 DQ1-DQ4 I/O GATE PRE- DECODER DATA OUTPUT 1,048,576-BIT BUFFER MEMORY REFRESH CELL ADD