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CP/M User
May 14th, 2006, 01:54 AM
Probably asked this before, but I was just wonderning what
differences these machines have?

I mean the Commodore Plus/4 has some built-in programs, though
does it come with BASIC as standard (like the C64), does it
share compatability with C64 programs?

Looking at the built-in programs the Plus/4 offers in which
you get a wordprocessor, spreadsheet, database and business
graphics software in ROM - so obviously it's designed for the
serious user. Looking further I see it also has built-in
Assembly Language - so perhaps it's slightly like an Amstrad
PCW - a machines designed for serious users, but certainally
capable of having Games for it. I just wondered though would
games written on a C64 would work?

If not then perhaps it was like an Amstrad PCW kind of machine
& had some games specifically written for it - anyone know?

CP/M User.

carlsson
May 14th, 2006, 03:26 AM
The Commodore 64 and Plus/4 are two rather different machines.

Basic: C64 uses V2, Plus/4 uses V3.5
Video: C64 uses VIC-II, Plus/4 uses TED
Audio: C64 uses SID, Plus/4 uses TED
CPU: C64 uses 6510 (one speed), Plus/4 uses 8501 (half/full speed)

The TED chip can display 121 colours, has some features that remind of VIC-II but completely lacks hardware sprites, thus making it a much worse games computer to program. The audio part of TED is nowhere near SID, although it is possible to make an external (?) SID cartridge hack, supported by a few programs.

Commodore Basic programs that don't use POKEs should be somewhat compatible though, but they are rather scarce. Don't expect any more advanced programs to be compatible. Although the CPUs are related, the memory maps and supporting hardware are different. Actually, the VIC-20 and C64 are a bit more inter-compatible even on machine code level, despite the different screen size might suggest otherwise.

The 3+1 productivity software in Plus/4 is mostly a joke, supposedly thrown in as a replacement for something else (speech synthesis?) that never materialized. It does have a built-in machine code monitor, but I don't know how powerful it is and you could always load one or have a utility cartridge on the C64 to get the same thing.

Having all that said, there were a bit of C16 and Plus/4 games, at least in the first few years after the launch. Today, the biggest scene is in former East Europe, where Commodore in the late 80'ties dumped surplus computers, making them very affordable even compared to locally produced clones.

CP/M User
May 14th, 2006, 04:13 AM
carlsson wrote:

> The Commodore 64 and Plus/4 are two rather different
> machines.

> Basic: C64 uses V2, Plus/4 uses V3.5
> Video: C64 uses VIC-II, Plus/4 uses TED
> Audio: C64 uses SID, Plus/4 uses TED
> CPU: C64 uses 6510 (one speed), Plus/4 uses 8501
> (half/full speed)

> The TED chip can display 121 colours, has some
> features that remind of VIC-II but completely lacks
> hardware sprites, thus making it a much worse games
> computer to program.

Amstrad CPCs don't have hardware sprites either (but that
stopped anyone) - the Z80 in it runs approx at 4Mhz though &
I'm guessing your going to tell me that the 8501 in the Plus/4
runs much slower?

> The audio part of TED is nowhere near SID, although
> it is possible to make an external (?) SID cartridge
> hack, supported by a few programs.

> Commodore Basic programs that don't use POKEs should
> be somewhat compatible though, but they are rather
> scarce. Don't expect any more advanced programs to be
> compatible. Although the CPUs are related, the memory
> maps and supporting hardware are different. Actually,
> the VIC-20 and C64 are a bit more inter-compatible
> even on machine code level, despite the different
> screen size might suggest otherwise.

It's a wonder no-one wrote a book outlining the machines
abilities & what the equivalent instructions or memory
addresses were for each of them.

> The 3+1 productivity software in Plus/4 is mostly a
> joke, supposedly thrown in as a replacement for
> something else (speech synthesis?) that never
> materialized. It does have a built-in machine code
> monitor, but I don't know how powerful it is and you
> could always load one or have a utility cartridge on
> the C64 to get the same thing.

But then you wouldn't be able to write the game of the century
for the Plus/4 - and have the entire C64 community
screaming! ;-)

CP/M User.

carlsson
May 14th, 2006, 12:01 PM
Well, of course it is possible to develop software sprite routines - as you wrote many games on Amstrad CPC, ZX Spectrum, VIC-20, Plus/4 and dozens of other systems use them, but it gets more difficult and the software sprites are often more limited in terms of colour clashes etc.

If I recall correctly, the 8501 runs at 1.76 MHz in fast mode (screen blanked?) and 880 kHz in slow mode. I'm not an expert on these systems, so I may have misunderstood it a bit, but it is thereabouts.

I'm quite sure there are books describing the various models and making parallel memory maps - at least I have one detailed memory map that spans from PET (Basic) V2 and V4, over VIC-20 and C64 and every entry that exists but is at another location is described, as well as those missing.

IMHO, if you want to write the game of the century today, you'd be cross-developing for most any 8-bit system. Advanced text editors, image converters, emulators, debuggers and then make the final testing on the target platform. When taking a such approach, a built-in machine code monitor is of some help, but not critical. Even if you develop on-target, I think you want a real assembler environment rather than a monitor.