Apple ///+ motherboard with 12V memory board

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amauget's picture
Last seen: 1 month 3 weeks ago
Joined: Jan 3 2011 - 11:34
Posts: 341
Apple ///+ motherboard with 12V memory board

Hi to All,

I have an Apple ///+ 820-0069B motherboard. I wanted to know of it is possible to use a 12V memory board with this model ?
There is not much information about the ///+. All the schematics I've found on and other web sites seem to be related to the Apple /// 12V motherboard only.

If it is possible, what are the steps ?
Based on this document, replacing the ROMs with 341-0042 & 341-0044 obviously. But what about R58 ?

Last seen: 3 hours 25 min ago
Joined: Jul 31 2014 - 17:48
Posts: 84
Re: Apple ///+ motherboard with 12V memory board

I found on page 196 of this doc it has some comment regarding R58. Looks like it is removed and a jumper wire installed in another spot for 256k.

Looking at pictures of the ///+ motherboard, I don't see R58, so I take this as it has the motherboard wired permanently for 256k. So then I don't think it will be possible to make it work easily.

The 12v memory board looks like it supports only 128k max?


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