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AlexC
Registered: Jan 2008
Posts: 293 |
Detecting REU + VICE
I'm looking for reliable method of detecting REU on different machines (c64/128) and VICE. Either I'm doing something wrong or the only really stable method (without actually writing to REU banks like shown here: http://www.codebase64.org/doku.php?id=base:reu_detect) is this one:
lda #$00
sta $df00
cmp $df00
beq noreu
The following code fails on my C128D:
http://www.willcox.de/index2.htm
At this point I don't need the size of REU as I assume that every single one will provide me with 128KB at least and this is as much as I need.
Thanks in advance
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tlr
Registered: Sep 2003
Posts: 1714 |
40 GOTO 10
;) |
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Frantic
Registered: Mar 2003
Posts: 1627 |
Hot Swap Gangsta |
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Bacchus
Registered: Jan 2002
Posts: 154 |
Comments on a few of the aspects here;
=> My program assumes REU to work and it *will* trash the content. So you should never start it if you want to preserve the REU content. As rightfully asked by LFT, I have no reason what so ever to maintain it's content as it will be trashed anyway when the main code starts. Having a polite scanner that doesn't touch the content is hence sort of pointless IMHO.
=> CRT - I found this method;
http://psw.ca/robin/?page_id=182
He stores value in the registers and read them back. It's different from my store and read back 256 times, but it looks a lot like what you describes. Right?
=> My general concern is hence not to preserve REU but I also want to ensure that cartridges work. A working set-up is to have RetroReplay and REU and I want that to work. |
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Trash
Registered: Jan 2002
Posts: 122 |
This is a piece of reu-checkcode I have used once upon a time. It isn't optimal in any way and trashes A + X registry and $df01, $df07 and $df08 but it works..
ChekREU ;returns carry = 1 if REU is present
sei
lda $01
sta store_01 + 1
and #$30
sta $01
ldx #0
stx $df08
cpx $d012
bne * - 3
dex
stx $df07
ldx #%10010011
stx $df01
store_01
lda #$00
sta $01
lda $d012
beq noREU
cli
sec
rts
noREU
cli
clc
rts
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Bacchus
Registered: Jan 2002
Posts: 154 |
Trash,
Thanx for the snippet. If I get it right you are setting up a compare, and such an operation takes time if the REU is there and no time if the REU isn't there, wherafter you use $D012 to validate if time passed. So the compare itself is not really relevant - it's the difference in duration you're after.
I buy that. It seems like a lot better way of doing it than trusting in memory at $dfxx being unstable where not REU is there.
Groepaz - how does that even work in VICE? Is there some sort of pseudo random return at reading the $dfxx addresses? |
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chatGPZ
Registered: Dec 2001
Posts: 11114 |
its not pseudo-random, it (open i/o) returns the last value that was on the bus, just like on the real thing :) |
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Bacchus
Registered: Jan 2002
Posts: 154 |
Didn't work :-(
Tried it on Vice but $d012 was 04 regardless if I have enabled or disabled the REU in the settings. Tried it using the REU function in 1541 Ultimate II+ but same result...
// Check REU - based on Trash's code
sei
lda $01
sta store01
and #$30
sta $01
ldx #0
stx $df08
vicloop: cpx $d012
bne vicloop
dex
stx $df07
ldx #%10010011
stx $df01
breakhere: lda store01: #$37
sta $01
lda $d012
bne reufound
noreu: lda #<noreutxt
ldy #>noreutxt
jsr $ab1e |
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chatGPZ
Registered: Dec 2001
Posts: 11114 |
doh - that code can not work when the first thing you are doing is switching off the I/O =) |
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Bacchus
Registered: Jan 2002
Posts: 154 |
Goepaz - it also doesn't work swapping in the I/O. |
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Trash
Registered: Jan 2002
Posts: 122 |
I doesnt work because I am stupid and used old code that never worked. I found my detection routine that works without trashing to much stuff:
;-------------------------------------------------------
*= $0810
sei
;-------------------------------------------------------
ldx #0
stx $df08
- cpx $d012
bne -
dex
stx $df07
; Exchange 255 bytes of c64 and reu memory
ldx #%10010010
stx $df01
; Exchange back
stx $df01
; D012 == 0?
lda $d012
bne +
; Yepp, no REU
lda #0
sta $d020
sta $d021
cli
jmp *
;-------------------------------------------------------
; No, REU
+ lda #1
sta $d020
sta $d021
cli
jmp *
;-------------------------------------------------------
The compare didnt work because it stop comparing at any difference. |
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