Justine Smithies on Nostr: In my quest to learn more about the 6309 8 bit CPU, I've discovered how to test if ...
In my quest to learn more about the 6309 8 bit CPU, I've discovered how to test if the CPU is indeed a real 6309 or just a 6809. #RetroComputing
LDD #$FFFF ; set all bits
CLRD ; 6309 opcode that runs as 8 bit on 6809
TSTB ; did it clear B (16 bit)?
BNE skip ; if not... not a 6309
LDMD #1 ; enable native mode
skip:
Published at
2025-01-02 22:24:33Event JSON
{
"id": "fa7b50b7e19f0669d74f6771cbe783df5a0c7bef701630c2d07684787f5afec5",
"pubkey": "76a830addb47903a3c8093772cd4b03d936ae4b4bb80810d42005249c84b517e",
"created_at": 1735856673,
"kind": 1,
"tags": [
[
"t",
"retrocomputing"
],
[
"t",
"1"
],
[
"proxy",
"https://snac.smithies.me.uk/justine/p/1735856673.774609",
"activitypub"
]
],
"content": "In my quest to learn more about the 6309 8 bit CPU, I've discovered how to test if the CPU is indeed a real 6309 or just a 6809. #RetroComputing\n\nLDD #$FFFF ; set all bits\nCLRD ; 6309 opcode that runs as 8 bit on 6809\nTSTB ; did it clear B (16 bit)?\nBNE skip ; if not... not a 6309\nLDMD #1 ; enable native mode\nskip:\n",
"sig": "4c8023bbbdc2c45483771a2d3484ccfd9094ed7e94508bcaa0aac41405c1ec59c921d42ce4dbeecbc5dba89515d927940ae8f297c366f95882c90b6b21dc0a8a"
}
