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Re: new Applicard
alex.freed.007@gmail.com wrote:
A logic analyzer shows that it is executing the code in the
boot ROM more or less as it should. I couldn't make sense of
some of the boot code. If left alone for over 2 minutes it
does start some diagnostics routine, but the last code written
to the Apple interface is $42 and it doesn't change any more.
This is likely an indication of some fault, but I don't know
how to interpret it. The OEM manual doesn't cover it.
To make the long story short, this prototype plugged into a real
Apple 2e acts much like my FPGA model: a lot of code is written
to the z80's memory and it loops in $F8Bx region waiting for
data from Apple. At the same time Apple loops around $B0Cx polling
for data from the z80. Needles to say neither CPU is getting anywhere
fast. Oh, and nothing got printed on the screen either.
Alex, I'm a little confused as to why the end state of a non-booted Applicard
is of concern. I believe that the host Apple invokes a hardware reset by
writing to a port, then proceeds to boot the operating system. They don't
operate in a vacuum waiting for something spontaneous to occur. For a certain
amount of time after boot, the Applicard is in a mode where the bootstrap can
take place.
IIRC, it loads part of the CP/M image into the Z80 memory and writes to a port
that banks out the ROM and replaces it with RAM before transferring control to
the bootstrap code.
Questions to everybody and Steven Hirsch in particular:
1. Any idea what the diagnostic code stuck at $42 means?
No, and I'm not sure why it matters.
2. Any software test I could run?
3. Please try the image http://mirrow.com/FPGApple/PCPI/pcpiboot.dsk
Does it work with a genuine Applicard? I don't have one unfortunately.
I will try this.
The best advice I can offer (since I'm not a hardware guru) is to carefully
review the Applicard schematic to ensure that you've actually modeled it
completely and correctly. Sounds like something fundamental is missing, but I
do not know what off the cuff.
I used to know the entire flow like the back of my hand, but it's been over 20
years and details are fuzzy. Last week I unearthed a box of documentation and
printouts and will try to make time over the holidays to refresh my memory. I
may be confusing the CardZ180 with the Applicard in some aspects and don't
want to lead you down a wild goose chase.
The cold boot code for the Applicard would probably help greatly if I can dig
it up.