Question about the Commodore P500?

[d***@yahoo.com]

Since the Commodore P500 has a VIC-II chip and SID, can C64 games be
easily ported to it? Has anyone written games for this machine? More
importantly, can VICE emulate it?

It's seems like a 40-column Commodore 128, sans CP/M, 80 columns and
BASIC 7.0.

Paul

[A. Fachat]

Post by d***@yahoo.com
Since the Commodore P500 has a VIC-II chip and SID, can C64 games be
easily ported to it? Has anyone written games for this machine? More

I don' think games can easily be ported - unless you have the source
code of the game. Then maybe.

Post by d***@yahoo.com
importantly, can VICE emulate it?

Yes, VICE can emulate it (AFAIR)

Post by d***@yahoo.com
It's seems like a 40-column Commodore 128, sans CP/M, 80 columns and
BASIC 7.0.

Kind of. It is related to the B600/B700 machines with similar memory
management, but 2MHZ CPU clock, and CRTC as video controller, not
the VIC - which makes them closer to the PET.

Andre

[l***@portcommodore.com]

All the chips are in mapped in different locations, the BASIC is in a
bank (kind of like in the 128) but starting at location 2. The BASIC
is more like 4.0, it has the extra DOS stuff but no graphics support
(remember these were released at the same time as the 64). Also it
uses IEEE-488 drives, which the 4040/2031 are not all that different
from 1541s but you can't depend onporting any fastloaders or other
protections that are familiar on the 1541/71.

Also in the US there are but a few P500s and in Europe they are more
abundant but still rare. I'd write for the B128 if you were going for
a CBM-II port, as there is a much wider audience.

Here is one cool bit though like the B128 the P-500 uses one RAM bank
for programs and the other for variables, so you can CONTINUE a program
after editing it without trashing your variables, also you should be
able to load different programs (as modules) in the same respect.

So, Paul, are you trying to port adventures to EVERY Commodore 8-bit
platform?

[Ullrich von Bassewitz]

Post by d***@yahoo.com
Since the Commodore P500 has a VIC-II chip and SID, can C64 games be
easily ported to it?

That depends a bit on the game. If the game is written in assembler
(most are), and it doesn't make much use of the ROM, then it is possible
without too much effort.

The VIC on the P500 can be programmed to read it's video data from bank
#0. If you run the program in bank #0, the setup is very similar to that
of the C64 with all ROMs banked out. Differences are

I/O chips: They're still located in bank #15, so addressing them needs
special code or subroutines.

CHAR ROM: The char ROM is inaccessible for the VIC in this mode, so
there must be character data in bank #0.

Post by d***@yahoo.com
It's seems like a 40-column Commodore 128, sans CP/M, 80 columns and
BASIC 7.0.

The banking is much different (less flexible but easier in my eyes), and
the ROM is less complex, which makes it easier to work without it.

Regards


Uz

[d***@yahoo.com]

Which brings me to another question: Just how many P500 are out there,
and do they function as workable machines? Some prototypes, such as the
C65, have a ton of UNIMPLEMENTED COMMAND ERRORS? (of which the C-128
has a few, surprisingly). I would assume that the P500 also has the
same problems(s).

Paul

[David Evans]

Post by d***@yahoo.com
Which brings me to another question: Just how many P500 are out there,
and do they function as workable machines? Some prototypes, such as the
C65, have a ton of UNIMPLEMENTED COMMAND ERRORS? (of which the C-128
has a few, surprisingly). I would assume that the P500 also has the
same problems(s).

I doubt it. The P500 runs, I believe, pretty much the B-series
BASIC so there shouldn't be much there that's unfinished.

[Ullrich von Bassewitz]

Post by d***@yahoo.com
Which brings me to another question: Just how many P500 are out there,
and do they function as workable machines? Some prototypes, such as the
C65, have a ton of UNIMPLEMENTED COMMAND ERRORS? (of which the C-128
has a few, surprisingly). I would assume that the P500 also has the
same problems(s).

The ROM of the P500 is pretty much complete (and quite similar to that
of the 6x0/7x0 series). There may be problems with the hardware that
went unnoticed because almost no units were sold. I'm still wondering
about the "write VIC/VRAM vectors" in the kernal ROM, but this may be a
left over from an old version. I've implemented P500 support for cc65
and ported a few C64 programs to the P500 without noticing any problems.

Regards


Uz


P.S.:
There's a cross-linked P500 ROM disassembly done by me available from

http://www.von-bassewitz.de/uz/oldcomputers/p500/rom500.s.html

(please be patient, the disassembly is more than 600KB).