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Re: Can anyone help me with Apple CP/M
In article <394E10EB.A0D0402C@pacific.net.au>,
Matt Jenkins <mdj@pacific.net.au> wrote:
> Paul Schlyter wrote:
>
>> If you really want to pursue this, I might be able to dig up some
>> old disassemblies I might still have, which might give you the
>> needed information faster than if you'd dig it up all by yourself.
>
> If you could do this, it'd be fantastic...
OK -- I have an "access time" of one or a few weeks to those listings,
since they are out in my country house, which I don't visit every day.
>> And, yes, you have another problem: you say you know how to handle
>> the Unidisk from 6502 assembly. How much code is needed for this?
>> A few tens of bytes? Then you might be able to squeeze it in
>> somewhere in $0300-$03FF = 0F300h-0F3FFh -- just watch out so you
>> don't overwrite stuff that's already there! Or is it hundreds of
>> bytes, or even a few kilobytes large? Then you must find space
>> elsewhere, e.g. by somehow moving down CP/M a KByte or so.
>
> Hmm, well, not that much code actually, since the smartport firmware
> takes care of most of the details. It's a nice clean logical block
> design, using 512 byte blocks, and the code is very simple to write
> if you have the smartport firmware and unidisk references.
So you might be able to squeeze it into $0300-$03FF then?
> How much detail does the softcard documentation go into on the boot
> process?
It gives no information at all. But you can disassemble the code and
look at it.
> I've been reading up on the CP/M BIOS layer in the manuals, and it
> doesn't seem to be a huge job to rewrite the whole BIOS, seeing as
> the Apple II hardware is so well documented. It's really only
> the disk routines and console driver after all (although serial port
> drivers would be a hassle).
Don't worry about the serial port drives. CP/M 2.2 had lousy support
for serial ports anyway, so any real application talking to the
serial port (such as Kermit) will have to be modified to talk
directly to the serial port hardware.
> it struck me this week that combined with some of the //e's nicer
> peripherals (3.5" disks, SCSI, Ram cards) that the right BIOS could
> lead to one of the slickest CP/M systems around. Imagine multiple
> CP/M partitions on a SCSI disk with a RamWorks style card being used
> to provide a disk cache :)
:-) ... well, you can always dream...
> But, I'm getting ahead of myself again. Any information you can provide
> on the internals of the softcard CP/M would be fantastic, if you don't
> mind taking the time to dig them up.
I'll look for info regarding hooking up new disk drives to the SoftCard
CP/M.
Then you'll also need a way to "format" the 3.5" Unidisks. You could
write that "disk formatter" to run under DOS 3.3, ProDOS, or
whatever. All it needs to do is to write $E5 into each and every
byte of each and every sector of the disk. That's it! To CP/M,
sectors filled with $W5 are acceptable as an empty root directory.
You cannot boot from these disks, of course, but let's assume you
boot from 5.25" disks anyway, so you don't have to worry about the
system tracks.
> Thanks,
>
> Matt
>
> PS - I believe there where some 60k CP/M systems for the Apple II as
> well. Does this apply to the PCPI Applicard, or some variant of the
> softcard ?
The Appli-Card had it's own 64K of RAM, so Appli-Card CP/M was a 63K
CP/M system (1K was needed for housekeeping stuff). Since the Z80
and the 6502 each had their own RAM on the Appli-Card, the two
processors needed a way to communicate. This was done via the Z80
ports, which mapped to RAM addresses as seen by the 6502: a protocol
was run in the Appli-Card system which enabled the Z80 and the 6502 to
"talk" to one another. Since the Appli-Card Z80 was unable to access
6502 memory at all, *all* I/O stuff had to be done via the 6502 in
the Appli-Card.
Then there was the CP/M Card, which ran CP/M+ aka CP/M 3.0. The CP/M
Card implemented memory banking, where the first memory bank was the
CP/M Card's own 64K RAM, and the second memory bank was the 6502 RAM...
FInally, to return to your question: yes, there was a 60K CP/M system
for the SoftCard too. It appeared fairly late, and it seems to have
been using that second 4K RAM bank on the Lanugage/RAM card of the
Apple II to gain another 4K of RAM.
--
----------------------------------------------------------------
Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40, S-114 38 Stockholm, SWEDEN
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