6809 2 External clock
XTAL (39) and EXTAL (38) slouží pro připojení krystalu, alternativně na EXTAL 38 mohou být připojeny externí TTL hodiny, XTAL se pak nechá nezapojený (plovoucí)
3 Missing instructions
- ABA ADD acumulator B to acumulator A
PSHS B ADDA ,S+
wer twtre
- wer
- something else
4 Optimalizace 6309
- AIM - AND with Immediate
7/4 AIM #~$40,V_ACIA_CTRL_byte 4/3 LDA V_ACIA_CTRL_byte 11/7 (nebo 7/4) vs. 4/3 LDA V_ACIA_CTRL_byte 2/2 ANDA #~$40 4/3 STA V_ACIA_CTRL_byte 10/8
7 Push order for 6809 stack:
(Made with DrawIt VIM plugin)
New S Old S
| |
| |
$0000 v v $FFFF
+--+- -+--+--+--+--+--+--+--+--+--+--+--+--+---+---+--+--+--+--+- -+--+
|..|.......|..|..|CC| A| B|DP|Xh|Xl|Yh|Yl|Uh|Ul|PCh|PCl|##|##|##|..|.......|..|
+--+- -+--+--+--+--+--+--+--+--+--+--+--+--+---+---+--+--+--+--+- -+--+
|Sh|Sl|
+--+--+ for PSHU ...
PUSH / PULL order
+-----+-----------------------------+
| CC | Condition Code Register | .
| +-----+-----------------------------+ /_\
| | A | A Accumulator | |
| +-----+-----------------------------+ |
| B | B Accumulator | |
P +-----+-----------------------------+
U | DP | Direct Page Register | P
L +-----+-----------------------------+ U
L | X | X Index Register | S
+-----+-----------------------------+ H
| | Y | Y Index Register |
| +-----+-----------------------------+ |
_|_ | S/U | Hardware/User Stack Pointer | |
\ / +-----+-----------------------------+ |
' | PC | Program Counter |
+-----+-----------------------------+