RAM replacements

I just got a MV-1FZ with a backup ram error pointing to a dead lower byte ram, so I was looking for a replacement of the outdated Sony CXK58257. I did not consider the 62256 because the only one I could buy easily is made by Cypress and on that the data lines do not correspond to the CXK:

CY62256 datasheet:
http://v4.cypress.com/cfuploads/img/products/cy62256.pdf

This led me to think any 62256 was not usable unless you want to rewire the data pins, which would result in a real mess.

However when I removed the bad ram I could see 62256 printed beneath the chip:

http://img.photobucket.com/albums/v65/nassivera/backupram1fz2.jpg

then I looked for a generic 62256 datasheet and the pinout was indeed the same as the CXK so why the heck is the Cypress one different? Anyone know of a manufacturer that makes a correct 62256?

Hitachi has the HM62256, I dont know how it compares with the Sony.

www.fh-bochum.de/fb3/ai/projekt/pdf/62256.pdf

After a bit of searching, find that also Mosel-Vitelic MS62256 has the same pin out as the Hitachi and I suspect the Sony (very different to the Cypress)
I guess thats the odd one out.

On the subject of RAM does anyone know if a SN7489 (16x4) RAM is the same as a N74S189. I have the correct type ordered, Im just curious and have been unable to find a pin out for the latter. Maybe like the Cypress version here the address pin outs are different.

ttooddddyy said:

On the subject of RAM does anyone know if a SN7489 (16x4) RAM is the same as a N74S189. I have the correct type ordered, Im just curious and have been unable to find a pin out for the latter. Maybe like the Cypress version here the address pin outs are different.

Click to expand...

Just received my 7489s from Mikes Arcade, they are not the same as the N74S189 I was using as a substitute. Maybe I can get this Gallag going after all