Confusion over character ROMs in a PET 2001

[Nivag Swerdna]

Someone has asked me to make up a characters-2.901447-10.bin 6540 ROM for them...

... this got me thinking!

When I bought my PET 2001-8 back a few years ago it had an original ROM and I never thought much about it... looking at my notes it says

MOS / MPS 6540 / 010 2678A which I worked out to be characters-1.901447-08.bin

The labelling is confusing and I suppose that this is really 901439-08.bin since it's in a 6540. I'm presuming the bits in a 901439-08.bin and a 901447-08.bin are the same, the former being a 6540 and the later a 2316.

So I think that's considered a reasonably early part, consistent with Basic Level I or II and so I just left it in the machine and didn't worry about it.

I subsequently built a ROM replacement gadget that allows me to change the main ROMs to Basic 1, 2, 3 or 4.... but I never changed the character generator ROM...

What have I been missing by not using 901447-10.bin?

I presume Commodore never made a 6540 ROM containing characters-2.901447-10.bin?

Thanks in advance

 

[dave_m]

Hers is what zimmers says about the ROMs:

901447-08.bin Character generator for BASIC 1. Slightly different mapping than in the
901447-10 ROM. This ROM has upper case characters where the characters-2
has lower case and characters-1 has lower case where characters-2 has
upper case

 

[Eudimorphodon]

For a "Graphics Keyboard" PET the swapped characters probably don't matter too much, given most software that casual people might want to play with (IE, games) keeps the machine in the graphics character mode. It would only matter if you tried running some kind of word processor or whatnot that expects the "fixed" upper/lowercase character set.

 

[dave_m]

It would only matter if you tried running some kind of word processor or whatnot that expects the "fixed" upper/lowercase character set.

Your mention of PET word processors reminded me of the old days at the Autonetics Division of Rockwell where we used a pretty good word processor called ‘WordPro’. It had most of the features used later by Wordstar for the PC.

Autonetics Semiconductor Group was a second source for the 6502 family of chips and Rockwell handed out PETs and AIM65s to any engineer that wanted one to learn about the 6502. We used PETs a lot as “poor man’s” IEEE 488 controllers in our quick and dirty internal test equipment. Our software guys soon developed a library of subroutine calls to help out the PET Basic.

In the late 80’s we switched to the IBM PC for word processing, spreadsheets, email, etc, but the PET was more fun and a great learning tool. I had one at home in 1978.