4118 Static RAM Chip, 1K x 8 bits

A7 --> 1 U






---4118---		 24 <-- VCC
A6 --> 2 23 <-- A8
A5 --> 3 22 <-- A9
A4 --> 4 21 <-- !WE
A3 --> 5 20 <-- !OE
A2 --> 6 19 <-- NC
A1 --> 7 18 <-- !CE
A0 --> 8 17 <-> D7
D0 <-> 9 16 <-> D6
D1 <-> 10 15 <-> D5
D2 <-> 11 14 <-> D4
GND   12 13 <-> D3
Pin Names and functions
A0 - A9 Address Inputs
D7 - D0 Data Input/Output
!WE Write Enable Input (Active LOW)
!CS Chip Select Input (Active LOW)
Vcc Power (5V DC)
GND Ground
Operating Characteristics
Parameter 4118-1 4118-2 4118-3 4118-4
Icc / mA typ 40
max 80
Access time / ns max 100 150 200 250

The 4118 can be replaced with the a power hungry CMOS chip - the 6116, so long as pin 19 is pulled to GND, VCC.
If connected to A10, it should provide twice as much RAM.