Hi Thomas!
Let me provide some more info about this confusing BS
thing.
Here's the original code in both banks:
; First bank
ORG $1000
RORG $B000
LDA $FFF8 ;4
JMP $BC96 ;3
-> All entry vectors are pointing to $BC96
; Second bank
ORG $2000
RORG $F000
LDA $FFF8 ;4
JMP $BC96 ;3
-> All entry vectors are pointing to $F000
Executing in Z26 as is provides the log as I posted
yesterday:
f000: ad f8 ff lda fff8
f003: 4c 96 bc jmp bc96
bc96: 78 sei
Now I needed 3 bytes for a STA WSYNC, Replacing the JMP
in the second bank with STA WSYNC:
; Second bank
ORG $2000
RORG $F000
LDA $FFF8 ;4
STA WSYNC ;3
When doing that, I get only a _black screen_ , even
though the Z26 log is starting straight with:
bc96: 78 sei
Next I tried this:
; Second bank
ORG $2000
RORG $F000
LDA $FFF8 ;4
BRK
NOP
NOP
This works as _fine_ as the original code, producing
even the same log again:
f000: ad f8 ff lda fff8
f003: 4c 96 bc jmp bc96
bc96: 78 sei
Phew...
Actually I now don't understand anything anymore.
What is the difference between placing either
STA WSYNC
or
BRK/NOP/NOP
after acessing a BS hotspot read when neither of the two
versions is actually executed?!?
Greetings,
Manuel
----------------------------------------------------------------------------------------------
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/
