Re: PET 2001 Fix....WAS: Will pay good money for NON working PET 2001 motherboard.

From: Philip Lord <>
Date: Wed, 25 Nov 2009 20:08:19 +0900
Message-id: <>
Yes the flame war is never ending...sometimes it goes quiet for a  
while, but ultimately resurfaces with some smart comment!!!

Your idea to take the VIC-1001 ROM and and just chop it up is simple  
and brilliant. I'm not sure why I didn't think of it myself ;-)
Anyway, I gave it a whirl, and as Mike suggested the Japanese fonts  
are now mapped to where the alternate graphic symbols are. The  
alternate character set uses all Uppercase, so no lowercase (I might  
make an alternate set with lowercase too).

I will put the bin file up on my server soon.
Mike, please try it out again. As for your idea of using a lager EPROM  
to switch between character sets, that was ultimately my plan.


On Nov 25, 2009, at 6:49 PM, Marko Mäkelä wrote:

> Hi Philip,
> On Wed, Nov 25, 2009 at 09:48:37AM +0900, Philip Lord wrote:
>> Thanks for the reply Marko,
>> Having never actually used a Commodore computer before (yes it's  
>> true. I
>> was a Sinclair guy growing up. Sorry)
> I can forgive you.  I hope that everyone can forgive me that I am  
> almost
> a Sinclair guy too (using GNU/Linux on x86 and x86-64, which are  
> remotely
> similar to the Z80). :-)  I started with the C64, then got a PC (with
> MS-DOS and Windows 3 in 1991, with GNU/Linux since 1993) and collected
> quite a few machines since then.  Last summer, I gave away all but the
> C64, VIC-20 and C128, and I have to confess that I haven't touched  
> those
> either.  Family and other hobbies are consuming my time.
> It has been a while since I read the Usenet, but is the annual
> comp.sys.sinclair+comp.sys.cbm flame war still going on? :-)
>> Anyway, just as a confirmation...are you suggesting in the second
>> character set, that I should replace the uppercase glyphs with the
>> Japanese, and then replace the the lowercase with uppercase?
> I was suggesting that you copy the uppercase/graphics set to both  
> halves
> of the ROM and replace the graphics glyphs in one half with the  
> Japanese
> glyphs.
> An easier alternative might be that you take the VIC-1001 character  
> and remove the inverted letters.  (I think that the PET does reverse
> graphics in hardware.)  That is, copy the first 1024 bytes, skip the
> next 1024 bytes, copy the next 1024 bytes (and skip the last 1024  
> bytes).
> 1024 = 128 glyphs*8 bytes per glyph.  The high-order bit of the
> character code indicates inverted graphics.  The VIC-20 character  
> ROM is
> 4096 bytes, while the PET character ROM should be 2048 bytes.
> 	Marko
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Received on 2009-11-25 12:00:04

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