Introduction

This is a EPROM and SRAM emulator that can emulate EPROMs that are pin compatible with the 27C040 and SRAMs that are pin compatible with the 62256. It has 32K of emulation memory and an open collector reset output to reset the target system. It can support 28 and 32-pin EPROMs depending on the jumper settings and the type of connector used.

• 28-pin SRAMs such in 8Kx8, 16Kx8, 32Kx8 organizations.
• 28-pin EPROMs such as 27C256, 27C512
• 32-pin EPROMs such as 27C010, 27C020
• Supports EPROMs with the OE# and A16 pins swapped.

Project status

I assembled two of these to extract the internal ROM from the HD647180 MCU used in Gaelco's "Master Boy" arcade game. It had a string printing routine that read a pointer list from external ROM and stored the results in VRAM. I used one configured as a 27C512 to replace the pointer data with offsets into the internal ROM area, and another configured as a 2Kx8 SRAM to "capture" the resulting bytes written to VRAM. This allowed the internal ROM to be read over several passes.

I also made a 16-bit EPROM emulator afterwards which has more functionality at the cost of less emulation memory.

Files