FLASH 23C1000

Summary

Adapter board to use a flash chip for the system rom in a NEC PC-8300.

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PCB: https://oshpark.com/shared_projects/BEby7Yjw

BOM: https://www.digikey.com/short/z8293n

Source: https://github.com/bkw777/aDIPters

References

Mask rom datasheet

File:UPD23C1000A.pdf

Old reference about pin-compatible parts:

https://www.web8201.net/Files/LIBRARY_web8201/NECPC8300_System_ROM_EPROM_Replacement.html

Compatible flash chips that can be used on this board (at least):

SST39SF010 https://www.digikey.com/short/z88hb8

SST29EE010

GLS29SF010

If your programmer software doesn't recognize the part number, just substitute "SST29SF010"

GLS29EE010 https://mou.sr/39tR5zu

If your programmer software doesn't recognize the part number, just substitute "SST29EE010"

If you think you might have a difficult time soldering the TSOP chip in the pre-loaded BOM above, you can substitute the PLCC version of the same part.

Any speed and any temperature range is ok.

Any TSOP32 or PLCC32(7x9) package is ok.

ROM images

NEC PC-8300 system rom: File:831000-438.bin

NEC PC-8300 system rom, Y2K patched: File:831000-438-y2k.bin

Directions

Building

See FlexROM_100 to see how to do the dip legs.
Search youtube for "drag solder" to see how to solder the TSOP legs with an ordinary soldering iron.

Suggest installing parts in this order:

1. Legs - The holes for the the legs are intentionally small and a fairly close fit on the legs. The legs should be installed first to avoid the problem where if you accidentally get solder in some of the holes while soldering the other parts near by, it can be difficult to wick the holes clean enough to insert the legs after that without vacuum.
2. R1, R2 - Especially R1 is surrounded by other parts, and especially if you are using a PLCC chip, the corner of the PLCC actually extends over top of part of of R1. So it's easiest to install R1 before anything else, definitely before the PLCC chip if using that type instead of TSOP.
3. TSOP or PLCC chip - Especially if you're using the 8x20mm TSOP chip, the jumper pins would be in the way and make it difficult to solder the TSOP legs.
4. Jumper pins - Flush-cut the posts on the bottom of the board after soldering.

You don't install R3 usually. It is for VPP on pin 1, to support EEPROM/EPROM devices that have a VPP pin. These are all old devices that aren't made any more, but you can still buy used and new-old-stock. Don't install R3 if you're using the SST39SF010A part in the BOM linked above, or any 29 or 39 series flash chip. But if you happen to already have a 28F010, 28SF010, 27SF010, 27C010 etc, you can use it instead of the 39SF010, and if so, you need to install R3. 47K the same as the others.

Programming

Requirements:

• eprom programmer, such as TL-866

No matter which chip or which package type you use on the board, the board provides a pinout on the DIP legs that matches the PLCC version of the chip when the jumper is in the PROGRAM position. To program the chip, just put the board into a programmers' ZIF socket as if the whole board were a DIP chip, and tell the programmer software that it is the PLCC version of whatever chip is soldered on the board.

Running

To use the board in the PC-8300, move the jumper to the RUN position and insert into the ROM0 socket in the PC-8300, leaving the 4 pins 1, 2, 31, 32 outside the socket.