Is that the uPD481850? I've attached the pinout pages from the datasheet, which was in the 1996 NEC databook on bitsavers.org

If so, it's an 8Mb SGRAM, arranged as 128k addresses, 32 bits wide, in 2 banks, in a 100 pin QFP package. I haven't had a close look at other datasheets, but it looks like there might be compatible parts, e.g. http://dosdays.co.uk/media/fujitsu/MB81G83222_Datasheet.pdf . But I've only done a 30sec check on some of the pinout, so I don't know if it's really compatible.

snufkin wrote on 2024-04-05, 18:38:

Is that the uPD481850? I've attached the pinout pages from the datasheet, which was in the 1996 NEC databook on bitsavers.org

It surely is. It is very common for NEC chips to omit the µP prefix on the chip marking.

so the uPD481850 will fit in place of d481850gf and do the same job?

caver99 wrote on 2024-05-12, 09:50:

so the uPD481850 will fit in place of d481850gf and do the same job?

The chip labelled NEC D481850GF is the NEC µPD481850GF. "GF" denotes the package PQFP100, which is the only package the NEC µPD481850 has been mass produced. So if you order a NEC µPD481850, you will surely receive a µPD481850GF, which will be labeled "D481850GF", so it will not just "do the same job", but it is the same type of chip. The correct way to spell the NEC part numbers is to start with the greek letter "mu" (µ), but these parts are also often inventorised by their ASCII transcription starting with "u". So when you order a uPD481850, you will receive a chip officially called µPD481850.