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From: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Newsgroups: comp.sys.apple2
Subject: Re: Quadram APIC-A //e compatibility & code debugging
Summary: machine-language kludge for interface
Message-ID: <1991Mar31.112001.28943@lynx.CS.ORST.EDU>
Date: 31 Mar 91 11:20:01 GMT
References: <50a3ec40.20b6d@apollo.HP.COM>
Sender: @lynx.CS.ORST.EDU
Reply-To: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Organization: The Universal Society for the Prevention of Reality
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Nntp-Posting-Host: jacobs.cs.orst.edu

In article <50a3ec40.20b6d@apollo.HP.COM> mort@apollo.HP.COM (Stephen Moriarty) writes:
>[...stuff about non-functional APIC-A parallel interface card...]
>Failing that, I'd like to debug the firmware. I've listed it out
>from the Apple monitor. If I had a printer interface, I could get
>a hardcopy ;(.

Sorry for posting two separate followups to the same article, but I didn't
think of this until after I sent the first article off on its way to
net-land...

In spite of the monitor-dump garbage you've been getting, it may still be
possible to get printouts of simple stuff like BASIC or machine-language
listings, assuming your interface works like most other parallel
interfaces.

1.  Make sure the interface is in slot 1.

2.  Enter the following machine language program into the monitor:

    300:A9 B 85 36 A9 3 85 37 4C EA 3 2C C1 C1 30 FB
    310:48 29 7F 8D 90 C0 68 60

    Check your work by typing "300L"--you should see something like this:

    0300-   A9 0B      LDA   #$0B
    0302-   85 36      STA   $36
    0304-   A9 03      LDA   #$03
    0306-   85 37      STA   $37
    0308-   4C EA 03   JMP   $03EA
    030B-   2C C1 C1   BIT   $C1C1
    030E-   30 FB      BMI   $030B
    0310-   48         PHA
    0311-   29 7F      AND   #$7F
    0313-   8D 90 C0   STA   $C090
    0316-   68         PLA
    0317-   60         RTS

3.  Activate the printer by giving the BASIC command "CALL 768" if you're
    using DOS 3.3, or "PR#A$30B" if you're using ProDOS.

If everything works out, all your commands should start going to the
printer instead of the screen.

Note that this simple driver does none of the fancy things that the
interface can do--i.e. no control-I 80N is available.

If everything comes out on one line, try to find a DIP switch on your
printer to turn on automatic line feed after carriage return.  If your
printer doesn't have such a switch, add the following machine code to the
driver:

     316:C9 D D0 4 A9 A D0 F5 68 60

The modified driver should look like this when you type "300L":

    0300-   A9 0B      LDA   #$0B
    0302-   85 36      STA   $36
    0304-   A9 03      LDA   #$03
    0306-   85 37      STA   $37
    0308-   4C EA 03   JMP   $03EA
    030B-   2C C1 C1   BIT   $C1C1
    030E-   30 FB      BMI   $030B
    0310-   48         PHA
    0311-   29 7F      AND   #$7F
    0313-   8D 90 C0   STA   $C090
    0316-   C9 0D      CMP   #$0D
    0318-   D0 04      BNE   $031E
    031A-   A9 0A      LDA   #$0A
    031C-   D0 F5      BNE   $0313
    031E-   68         PLA
    031F-   60         RTS

If your interface works like every other parallel interface I've ever seen,
then one of these drivers ought to work.  In most parallel interfaces, the
byte at $CnC1 (n=slot number) is negative when the printer is busy and
positive when it's ready for data, and the data is written by storing it at
$C0n0 (n=slot number+8).

Good luck!

	       - Neil Parker
--
Neil Parker                 No cute ASCII art...no cute quote...no cute
parkern@jacobs.cs.orst.edu  disclaimer...no deposit, no return...
parker@corona.uoregon.edu   (This space intentionally left blank:           )