Well, you guys have forgotten more about PETs than I ever knew, so I
must be missing something since I didn't think any actual decoding
was necessary for the ROMs. Can somebody point out why it wouldn't
work to plug a 4K chip into the lower socket and just connect CS4 to CS 
and CS3 to A11, and for the E ROM, CS3 to OE instead?

I guess I could go down to the dark and musty lab and discover for myself 
what I'm overlooking. I made an adapter a long time ago to read 6540s in 
my programmer in order to find a bad one, so it shouldn't be a big job 
to go the other way (if I can find it) ;-)

Yes, Nicolas, it was the super-duper replace-anything RAM/ROM board
I was curious about; looking at your website it kinda looks like it's been
out of stock and more or less dormant for some time. If/when you make
some more, any rough idea of price?

TIA, and nice to meetcha!

mike (in Toronto)
***********************************************************************************

----------
From: 	Nicolas Welte[SMTP:no_spam@x1541.de]
Sent: 	Wednesday, May 06, 2009 4:29 PM
To: 	cbm-hackers@ling.gu.se
Subject: 	Re: RE: FLASH ROM replacement

Hi,

> What's the story on the fancy Welte board? Is it still available, either
> built 
> or PCB and logic?

The 6540 and 6550 adaptors are available as PCB only or DIY kit with all parts. But they work only in the video part of a 2001 board, because they don't decode the chipselect lines. In the video circuit, RAM and ROM are always enabled.

I have the universal 6502 RAM/ROM expansion board (aka PETRAM) which goes into the 6502 socket of a 2001 PET, and it can be used to replace all 6540 ROM and 6550 RAM. Unfortunately, I am out of stock with this PCB, and my next reorder depends on my completion of another unfinished project, so I can get better prices for the PCBs by bundling the PCB order.

Nicolas

 

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