Re: PET II questions (P500, B128, B256)

From: William Levak (wlevak_at_cyberspace.org)
Date: 2001-12-12 23:31:04

On Wed, 12 Dec 2001, Nicolas Welte wrote:

The ROM select lines are not on the expansion connector.

> William Levak wrote:
> > There used to be an adapter board that would replace 4 6550s with 4 2114s.
> > I think it was made by Skyles.  Even when the original PET was still in
> > use, it was cheaper to buy the adapter and 4 2114s, than replace 2 6550s.
> 
> Today I would use an even simpler approach: Remove all RAMs and ROMs (except
> video and character) from the board, and connect a single 32kB SRAM chip and
> a single EPROM to the expansion connector. Would eat a lot less power than
> the original circuit, but of course it would also look a lot less original.
> But it would leave a lot of spare 6550 chips for the video RAM, and only the
> character ROM would have to be replaced with an EPROM on an adaptor socket.
> Switching between ROM versions would also be very easy. Maybe I'll take this
> approach for the dead 2001 board.
> 
> Nicolas
> 
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> 


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