VIC20 / C64 chargen

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Bobbi
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VIC20 / C64 chargen

Post by Bobbi »

Is it just me that thinks the C64 looks way better with the VIC20 chargen ROM?

For that matter, the VIC looks much better with the C64 chargen too.

Maybe I will swap them!
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Kweepa
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Re: VIC20 / C64 chargen

Post by Kweepa »

It's just you :)
The C64 looks better but the VIC looks much worse, IMO.
Of course on a TV the C64 would be less readable...
Bobbi
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Re: VIC20 / C64 chargen

Post by Bobbi »

I am thinking with a modern TV and a composite connection (no RF) the VIC20 chargen is the better choice.
Since I have a few VICs I may 'borrow' the chargen from one of them for my C64.
Boray
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Re: VIC20 / C64 chargen

Post by Boray »

Try the vic-20 chars on a real c64 and you will understand why they changed it.
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Bobbi
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Re: VIC20 / C64 chargen

Post by Bobbi »

Will try it and see. My plasma TV gets a much better picture from composite input than my old CRT did from the RF signal back in 1982! I think for TVs using the modulator you are probably tight that the C64 needed those fat characters to avoid colour fringing. I really don't like the C64 font and would much prefer if it were more VIC-like!

As I understand it, Japanese versions of the C64 had the VIC-20 font (plus some Japanese characters similar to VIC-1001.) They also had the white on cyan screen colours of the VIC-20.
Boray
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Re: VIC20 / C64 chargen

Post by Boray »

Bobbi wrote: As I understand it, Japanese versions of the C64 had the VIC-20 font (plus some Japanese characters similar to VIC-1001.) They also had the white on cyan screen colours of the VIC-20.
I didn't know that. The SX-64 also has the Vic-20 colors.
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eslapion
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Re: VIC20 / C64 chargen

Post by eslapion »

Bobbi wrote:Maybe I will swap them!
It won't work!

There is something really itchy about the 2332 ROMs used to generate the characters on the VIC and 64. There is a secondary chip select line on them (pin 21).

On the C64, it is active high and just tied to +5V but on the VIC-20, it is active low and it is used in a very specific way so it can't just be tied to the ground or you'll cause bus conflicts.

That's why I can't use my MCM68764/MCM68766 EPROMs to make replacement character generators for the VIC but there's no problem with the C64.
Be normal.
Bobbi
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Re: VIC20 / C64 chargen

Post by Bobbi »

I just tried it and you are quite right!! Doesn't work at all. Characters look like random scuzz with the VIC-20 chargen.
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orion70
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Re: VIC20 / C64 chargen

Post by orion70 »

Kweepa wrote:It's just you :)
The C64 looks better but the VIC looks much worse, IMO.
Of course on a TV the C64 would be less readable...
Yep same opinion here, I guess it's okay​ only in x64.
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Mike
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Re: VIC20 / C64 chargen

Post by Mike »

With an adapter socket, a 2732 can be used as replacement character ROM, see the thread "Request help on replacing 2332 4Kx8 Char ROM -> Fixing a VIC".

However, the character ROM is not only used by VIC to display text screens with the standard font - the CPU also has access and there actually exist quite a few programs that show unexpected behaviour when the contents of the character ROM are changed from the default.

If you want to use the C64 character set on a VIC-20, or vice versa, you always have the option to use a copy in RAM for that.
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eslapion
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Re: VIC20 / C64 chargen

Post by eslapion »

Mike wrote:With an adapter socket, a 2732 can be used as replacement character ROM, ...
Correct.

See pinouts here: (where ROM is the pinout of the 2332)
Image
The socket is not very complicated, swapping pins 18 and 21 does the job.

Added edit: the C64 CG ROM has a custom characteristic, the CS2 (pin 21) is active high.
Be normal.
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