Re: Hardware emulation of 6509 using 6502?

From: smf <>
Date: Wed, 25 Jul 2018 10:33:44 +0100
Message-ID: <>
On 24/07/2018 23:43, Mia Magnusson wrote:
> Sound would be hard anyways. In theory you could remap the PET sound
> I/O pin to the volume control register of the SID if it happens to use
> the right bits.

I was mostly thinking about allowing the CB2 pet sound to be remapped 
from the VIA to the CIA and let the user come up with a way of getting 
that to produce sound.

You could then either run a speaker from it how you did on a pet, or 
direct it to the sid audio input.

> But who did use joysticks on a PET? I've never heard of that.

Adding joysticks and sound was a relatively common upgrade, there were a 
few different schematics.

The standard one has 2 joystick ports.

Vice supports them.

> Well, as there is only one setting of the 6545/6845 that right for a
> given monitor it might be best to not expose those registers to old PET
> programs.

Sure, blocking that would seem a good idea.

> Basic won't use pokes to 0/1 unless it also contains machine code
> programs.

Yes, but some machine code might still work. You should either block it 
by denying the poke to 0/1, or try to come up with an alternative that 
remaps it.

Letting the program just die would seem annoying to a user.

> A VIC-20 emulator for C64 would imho be rather useless as you can't
> emulate anything near how the display hardware works. If it were
> possible to set VIC-II to a variable amount of chars per line it could
> work better though.

Running pet programs on a cbm2 is rather useless too, a pc running vice will do the job better. Isn't it just about the challenge of doing it?

I don't recall ever seeing the vic20 emulator run, but I remember it 
mentioned at school as being printed in a magazine & I assume it just 
uses 22 columns of the screen
Received on 2018-07-25 12:03:35

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