Commodore 64 & Commodore Plus/4

[CP/M User]

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]

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]

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]

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.

 

[charleslocket]

Well, as other reply tells, there a a few differences between the C64 and plus4 commodore computers, but to resume I woudl say enssentially and as I read previsouly, the plus 4 does not have the SID sound chip, so less sound features, but has a lot more advanced basic language, whereas the C64 had only the antic PET basic minus the assembler monitor! So the plus 4 was as easy to program and exploit then C64 was a night mare made if peeks and pokes for any graphic and sound needs, not to mention erasing the graphic screen with a bsic loop was teking an ethernity, so need to write short assembler routine and poke it inisde the morty before excuting! but without the help of the assembler program...
An. other way to resume without the sound sid chip and sprite graphic capabilitiers the plus 4 was filled in all the swtware they could whereas the C64 had quite none juste becuase probably put on the market as fast as possible because of the VIC20 selling quickly going down! So no time to develop a basic with features to exploit all its very nice electronic features.
Of course so most softwares are not compatible between the two models unless written exclusively in PET basic language!
The C64 had been a terrible deception for me at the time! I thought I bought kind of best deal of features for a personnal computer, but had nothing better than a pet to play with as basic programmers! Always thought I must have rather bought a Dragon 32 instead! much cheaper and much more fun to use, unless you are only inetresting in expensive computer game cartridges!
You could also buy the Simmons Basic, for the C64, but it was very pricy! I bought insteall the Tool64 cartridge, with I discovered was adding bugs! Use of the extra tool 64 basic commands was resetting the RND function, so always the same nomber coming out of the rnd() fonction after use of one of these extra basis commands!!!
After all this incedible commodore finally did such a success fooling that much customers!!!!