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

RAM Front

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