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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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ThunderBlade
Registered: Jan 2002
Posts: 75 |
I want to put a non-intrusive (read-only) REU detection routine in my kernal ROM, so it's executed upon reset. So I see immediately if I have my REU enabled (in 1541Ultimate) or not.
I like the idea of reading $df00, it's the REU status register and as suggested, reading it a couple of times and it never changes, I should be fine. BUT! Action Replay also has stable values at $df00. And 1541U supports tons of other freezers and CRTs that *may* have stable values at $df00.
What's your opinion... currently I think it could be safe to read the other REU registers like C64 address, Interrupt Mask register etc. If they are there with default values (after initial test of stable value at $df00) it should be safe to assume an REU. The values seem to be reset to default upon reset of the C64/1541U... |
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Burglar
Registered: Dec 2004
Posts: 1031 |
so, instruct reu to copy data from reu to c64, if data was overwritten, you got a reu enabled. |
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Count Zero
Registered: Jan 2003
Posts: 1825 |
Plain reading of registers without an actual transfer is likely to fail with quite a few cartridges. So, what Burglar sez. |
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ThunderBlade
Registered: Jan 2002
Posts: 75 |
Ok, thanks. I was more afraid of messing around in $DFxx area could lead to unpredictable behavior/crashes with some other (not REU) cartridges. |
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