A single 62256 Static RAM chip provides 32K of memory to the Z80. Address line A15 goes through a NOT gate on a 74LS04 to the /CE pin, thus mapping this memory to address 0x8000 – 0xFFFF. The /WE and /OE lines are controlled by ORing the /MREQ with the /WR or /RD from the Z80
Click the image below for schematics in PDF format
Only 1 of the 6 NOT gates on the 74LS04 is used, which is wasteful
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Bill of materials
- 34 pin RA Header
- 28 pin wide DIL socket
- 14 pin narrow DIL socket
- 74LS32
- 74LS04
- 62256 RAM
