Re: commdore plus 4 cartridges

From: Rob Clarke <*crock_at_clarke-family.org.uk*> Date: Thu, 26 Apr 2012 22:52:01 +0200 Message-ID: <4F99B571.70304@clarke-family.org.uk> · crock_at_clarke-family.org.uk

>  They can be replaced by 27128 EPROMs (or 27256 with the data in the 
> upper half) if one little detail is fixed. The 27128 expects Vpp on 
> pin 1 and, in normal operation would like to see Vcc (+5V) there. The 
> ROM sockets on the C16 and C116 PCB take this in account and have pin 
> 1 connected to +5V. The ROM sockets in the Plus/4 do not (all 4 of 
> them) and it look like the cartridge you photographed doesn't either. 
> Usually the EPROMs work anyway, but it's not according to spec. So if 
> you do your own layout, it would be a good idea if you'd connect Pin 1 
> of each ROM socket to +5V on your board.
>
Hi, pin 1 is connected to +5v on the standard +4 cartridge boards, like 
Didiers. You can't see the trace though as it's on the top side hidden 
under the ROM's.

Rob

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