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JackAsser
Registered: Jun 2002
Posts: 2014 |
Detect C128 in C64-mode without exploiting 2mhz mode?
Reason: Easyflash emulation in 1541u2 doesn’t work in 2mhz mode. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: That’s the follow up question!
First I want to detect c128 in a safe way and offer 2mhz mode and then add a disclaimer for 1541u2 user or detect it and disable the feature |
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chatGPZ
Registered: Dec 2001
Posts: 11387 |
Why not just offer it as an option (default disabled)? Autodetection is doomed to fail in one way or another :) |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: Why not just offer it as an option (default disabled)? Autodetection is doomed to fail in one way or another :)
It is an option already.. yeah. Maybe add a disclaimer |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Currently making the automap to show on the VDC always. It would be very nice not to have to enable it explicitally. Any options? I don’t wanna mess with the VDC regs unless I’m sure it’s really there. Can you reliably detect the presence of a VDC-chip? I know several possible solutions but is also afraid of GP’s ”doomed to fail”. Is detecting a VDC chip really doomed to fail? |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
FWIW, currently doing:
ldx #0
ldy #5
stx VDCADR
:
bit VDCADR
bmi vdcFound
inx
bne :-
dey
bpl :-
rts
vdcFound:
inc vdcPresent
rts
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Krill
Registered: Apr 2002
Posts: 2981 |
Since your detection routine is writing to a VDC register, i'd suggest reading a byte from VDC RAM, writing it back inverted, then reading it again. |
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chatGPZ
Registered: Dec 2001
Posts: 11387 |
and i'd suggest to use a couple different bytes on subsequent addresses, so it doesnt fail randomly (or to be exact: fails much less likely randomly) because floating bus :) |
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Krill
Registered: Apr 2002
Posts: 2981 |
Yeah, use the auto-increment feature to write-read some magic words. =) |
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Oswald
Registered: Apr 2002
Posts: 5095 |
Quote: FWIW, currently doing:
ldx #0
ldy #5
stx VDCADR
:
bit VDCADR
bmi vdcFound
inx
bne :-
dey
bpl :-
rts
vdcFound:
inc vdcPresent
rts
probably I'm missing something here, but if d600 is open io you may get bits set at VDCADR just randomly? |
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chatGPZ
Registered: Dec 2001
Posts: 11387 |
Indeed. And for more fun, its not exactly random, but depends on what the VIC fetched in the previous cycle :) |
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