Date : Thu, 21 Mar 1991 09:39:51 GMT
From : csusac!sactoh0!ijpc!ianj@ucdavis.ucdavis.edu (Ian Justman)
Subject: Re: Z-80 Softcard Question???
umsmit72@ccu.umanitoba.ca (Kenneth G. Smith) writes:
>
> I have recently obtained a CP/M card for my Apple II+ computer (without
> documentation) and was wondering if anyone could help me out with a few
> questions...
>
> 1) The card has four binary switches on it. They are all set to the
> OFF position. I was wondering what exactly these switches are for.
Two turn interrupts on and off, one deals with memory mapping
(the Z80 card remaps the system's memory rather radically to take
into account that Pages 0-3 are sacred to the 6502, but you can
alternatively switch that mapping off to make the Z80 see it as
the 6502 sees it; for CP/M to work properly, you MUST turn
mapping on because you don't want the 6502 and the Z80 throwing
each other curves... (grin). Also, the point needs to be made
that the card in question, the Softcard, distributed by
Microsoft, as in the ORIGINAL Softcard, not the Softcard //e,
talks DIRECTLY to the Apple hardware just like the 6502 does. In
fact, when the Z80 has control, it puts the 6502 to sleep (I
believe it does nothing more than execute wait states).), and the
remaining one controls how the card interfaces to the Apple DMA
daisy chain.
The switches are like this:
sw1 sw2 sw3 sw4
MEM MAP DMA IRQ/INT NMI <--- SAME ON BOTH
DAISY ^ ^
CHAIN | |_ Z80 NAME
|_____ 6502 NAME
Sw1: On: Disables memory remapping
Off: Enables memory remapping (Apple CP/M default)
Sw2: On: When DMA daisy chain input is dropped low, the Z80
will drop what it's currently doing to let a
high-priority device do some DMA and relinquish
control back to the 6502
Off: Won't stop at all no matter what priority device is
requesting DMA
___ ___
Sw3: On: Hooks the Z80's NMI line up with the Apple's NMI line
on the expansion bus so the Z80 will be interrupted
upon receipt of a non-maskable interrupt. The
Softcard recommends that interrupts, maskable or not,
should be handled by the 6502 which also sees the
interrupt, so it can clear its interrupt status and
return control back to the Z80.
Off: Disconnects the line.
___ ___
Sw4: On: Hooks the Z80's INT line up with the Apple's IRQ line
on the expansion bus. Discussion is the same as
above.
Off: Disconnects the line.
The default settings for the switches should be all of them off
for Apple CP/M to work properly.
> 2) Of the several disks I obtained with the card, I have a program
> called 'NULU' which deals with libraries. I was wondering what the
> purpose of a library is and how you go about using one. I have
> only one '.LBR' file on the disks called 'LUX42.LBR' (on the modem7
> program disk) and haven't been able to manipulate the data in it to
> any great extent (other than listing it's members using 'NULU').
LUX will deal with libraries too, but they're designed for
RCP/M's. To extract the LBR's contents (provided they're not
compressed), type "-x" and then a drive/file specification, most
often times the file specificaiton will be "*.*" to extract
everything. If you were to type "-x b:*.*" at the NULU prompt in
an open library, that means to extract all the files to drive B:,
but it won't unsqueeze the files if they're squeezed (those
files, often times, will have a "Q" as the second letter of the
file's extension). For those files, use "-q" instead of "-x".
To unsqueeze all files with Q as the second letter of the
file type, type "-q b:*.?Q?" which will unsqueeze (or try to) all
files with the letter "Q" as the second letter in the file type.
Most CP/M programs with multiple files are in the .LBR format,
but there are the occasional .ARK, .ARC, and .ZIP files.
> I believe the card is refered to as a Z-80 Softcard and doesn't appear
> to have any manufacturer's markings on it. Therefore, I don't believe
> it is actually an Apple made card.
As I said a couple of paragraphs ago, they were distributed by
Microsoft.
> Can anyone enlighten me soas I may get the maximum use out of this
> system. I have used the CP/M OS with some success and really like what
> it does for my rather modest system.
If you have used CP/M on other computers, then using CP/M program
on the Apple will be more or less the same as you have used them
on, say an Osborne, a Kaypro, an SBC, or an S-100 box. However,
if you plan to do a lot of stuff between operating systems,
particularly in ProDOS, I very much suggest that you get a
program called "Chameleon" which runs under Apple ProDOS and will
transfer between all four major diskette formats, i.e. DOS 3.3,
ProDOS (you'll need this to run Chameleon), Pascal (it will only
support the 5 1/4" variety, I believe), and CP/M.
Have fun!