[Coco] F9dasm and bad 6809 op codes

[John Guin]

DEY is decrement Y register and PSHX is push (to) X register, or X register to the stack (I can't remember off the top of my head).

John

-----Original Message-----
From: Coco <coco-bounces at maltedmedia.com> On Behalf Of Allen Huffman via Coco
Sent: Friday, November 21, 2025 6:13 PM
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Cc: Allen Huffman <alsplace at pobox.com>
Subject: [Coco] F9dasm and bad 6809 op codes

Is there such an op code as DEY or PSHX?

Both are generated by the f9dasm disassembler:

        LDY     M3AFD                    ;3A04: 10 BE 3A FD    '..:.'
Z3A08   DEY                              ;3A08: 31 3F          '1?'
        BNE     GETKEY                   ;3A0A: 26 05          '&.'

...then later...

        LEAX    -$05,X                   ;3A6D: 30 1B          '0.'
        PSHX                             ;3A6F: 34 10          '4.'
        LDX     #DCOPC                   ;3A71: 8E 00 EA       '...'

Any op code but experts out there?  The 31 seems to be LEAY $3F,Y, perhaps. Unsure about the other. The document I am looking at is not OCR'd so I cannot do a search in it.

                - A

Code:

https://github.com/Arakula/f9dasm

My files:

https://github.com/allenhuffman/SubEthaSoftware/tree/main/OS-9/MultiBoot/asm

The dat file (one directory higher) also exists as data numbers in my C program, so I used a Python script to spit those data numbers into multiboot.bin and am working from that.

Earlier, I was doing it from an Intel HEX file. I was having problems there, too, so switched to the .bin approach - same issues.

Just me?

                - A


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