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

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) It's a little difficult for me  
to understand how the characters work. I have installed VICE on my  
Laptop, but as I don't have a numeric keypad, and therefore the  
keyboard mapping is all screwey and it's not very usable, especially  
when trying to understand the keyboard and characters for the PET.

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?

Phil

On Nov 24, 2009, at 10:27 PM, Marko Mäkelä wrote:

> On Tue, Nov 24, 2009 at 07:53:33PM +0900, Philip Lord wrote:
>> Just a quick follow up, and a question for the list:
>> The original character ROM contains two sets of capital letters,  
>> and on
>> set of lower case. Does anyone know why there are two sets of cap
>> letters?
>
> There actually are two 128-char character sets in Commodore 8-bit  
> computers:
> uppercase/graphics and lowercase/uppercase.  On models where reverse
> characters are not implemented in hardware, the character sets are  
> 256-char,
> but the upper half is the same as the lower half, but inverted.
>
> In the home computers (VIC-20 and later), you can switch between  
> these two
> character sets by pressing SHIFT and the C= key.  If I remember  
> correctly,
> that does not work in the PET.  But these control codes should work:
>
> print chr$(14); rem ctrl-n selects lower/upper-case
> print chr$(142); rem shift-ctrl-n selects uppercase/graphics
> print chr$(8); rem ctrl-h disables SHIFT+C=
> print chr$(9); rem ctrl-i enables SHIFT+C=
>
> Some graphic characters exist (and are identical) in both sets.  These
> graphics are what you obtain on the VIC-20 and later when pressing  
> the C=
> key together with a letter key.
>
>> Presently I have replaced the lowercase letter set with the new  
>> Japanese
>> fonts. Hopefully this was the correct thing to do. A poke 59468,14  
>> should
>> activate them. However you do lose the lowercase characters of  
>> course. If
>> you believe I have made a mistake, please let me know.
>
> I am just guessing, but I would expect that the original font  
> preserved
> positions 1 to 26 (a to z) intact.  Those would correspond to the  
> lower case
> letters in the lower/uppercase character set.  If the Japanese  
> glyphs are
> put where the uppercase letters used to be (65 to 138), then it  
> would make
> sense to replace the lowercase glyphs with uppercase ones at 1 to 26.
>
> For what it is worth, I found a homebrew EPROM in a VIC-20 that had  
> replaced
> some of the C= graphics characters with accented letters.  The  
> official
> Swedish/Finnish modification had the chars at [\].
>
> 	Marko
>
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