Log inRegister an accountBrowse CSDbHelp & documentationFacts & StatisticsThe forumsAvailable RSS-feeds on CSDbSupport CSDb Commodore 64 Scene Database
You are not logged in - nap
CSDb User Forums


Forums > C64 Coding > Detecting REU + VICE
2009-01-08 00:29
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
 
... 32 posts hidden. Click here to view all posts....
 
2017-02-07 09:33
AlexC

Registered: Jan 2008
Posts: 293
Somehow I can't belive that through all those years nobody came up with definitive solution for the problem. Agree with JA: what is wrong with this solution?
2017-02-07 19:33
chatGPZ

Registered: Dec 2001
Posts: 11088
i'd do this:
- write $ff to some location
- set up DMA REU->C64 for a single byte, target on the choosen location
- trigger DMA
- check if still $ff, no -> REU present
(need to repeat incase the byte in reu was $ff)
- write $00 to that location
- trigger DMA
- check if still $00, no -> REU present
- else -> no REU present

or you could do what eg wheels does, i extracted the check once: https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/REU.. (this also detects the amount of REU RAM, i think)
2017-02-07 22:13
Bamse

Registered: Apr 2013
Posts: 7
Just thinking:
Set up a dma for some bytes, no fixed address, execute with autoload off, then reload $df04 (or was it?). Increased value = REU present.
2017-02-07 22:24
lft

Registered: Jul 2007
Posts: 369
Another option is to run some non-destructive operation such as REU compare, and measure if there were lost cycles, and how many.

There's one thing I don't quite see, however. What is the point of detecting a REU if you aren't planning to use it? And when you use it, you'll trash whatever ramdisk was there. So why exactly do programs in general need non-destructive REU detection?

I think it makes more sense to warn the user that the REU is about to be used (whether it exists or not), and wait for a go-ahead. Also, REUs are often virtual these days, and this approach would provide an opportunity to enable the REU while the program is running.
2017-02-07 23:31
chatGPZ

Registered: Dec 2001
Posts: 11088
or pop it into the c64! (rock'n'roll!)
2017-02-08 00:34
CRT

Registered: Oct 2012
Posts: 87
I read several clever methods here.

In Globe I just filled the REU registers and read them back, not my invention but does the trick.. "roughly". It does give a false positives with my EF3.

Could REU detection cause more serious trouble with other carts in the DF00 area? Like system freeze-up, etc. Poking wildly into an unknown device might not always be the best idea.
2017-02-08 08:35
Trash

Registered: Jan 2002
Posts: 122
I wrote some REU code a while ago and I tested for the reu by lda $d012, doing a compare of 256 bytes, sbc $d012 and comparing if the result was greater than 3...

But as CRT mentions, poking wildly into an unknown device could yield some unwanted results, you're better off just stating that a REU is required and have a manual confirmation or warn that you will be trashing the registers @df00...
2017-02-08 14:40
chatGPZ

Registered: Dec 2001
Posts: 11088
crashes are expected when there is some cartridge - like FC3 :)
2017-02-08 17:46
Frantic

Registered: Mar 2003
Posts: 1626
Whatever nice solution you guys come up with in the end, don't hesitate to add it to codebase:

https://codebase64.org/doku.php?id=base:thirdparty#reu

:)
2017-03-18 13:01
Repose

Registered: Oct 2010
Posts: 222
There is a good reason to be careful. There's not just REU and it might be at different locations, with a port expander.

So I wrote the official test code for sid symphony, see if you can find that disk.

It carefully detects for REU, Snapshot, snd sid chip, at any location. I believe it also does size or maybe I didn't bother, but size is tricky because the size bit can be the same in two models, you have to actually write ram.

I often had two devices plugged in at once, so I need that.

Btw some tests will actually freeze your computer in one or other device, by mapping out your ram oops
Previous - 1 | 2 | 3 | 4 | 5 - Next
RefreshSubscribe to this thread:

You need to be logged in to post in the forum.

Search the forum:
Search   for   in  
All times are CET.
Search CSDb
Advanced
Users Online
Bob/Censor Design
Mikael/Pretzel Logic
deetsay
hedning/G★P
Aomeba/Artline Desig..
Matt
Hani
Nordischsound/Hokuto..
Guests online: 288
Top Demos
1 Next Level  (9.8)
2 Mojo  (9.7)
3 Coma Light 13  (9.7)
4 Edge of Disgrace  (9.6)
5 No Bounds  (9.6)
6 Comaland 100%  (9.6)
7 Uncensored  (9.6)
8 The Ghost  (9.6)
9 Wonderland XIV  (9.6)
10 Bromance  (9.6)
Top onefile Demos
1 Party Elk 2  (9.7)
2 Cubic Dream  (9.6)
3 Copper Booze  (9.5)
4 Rainbow Connection  (9.5)
5 TRSAC, Gabber & Pebe..  (9.5)
6 Onscreen 5k  (9.5)
7 Dawnfall V1.1  (9.5)
8 Quadrants  (9.5)
9 Daah, Those Acid Pil..  (9.5)
10 Birth of a Flower  (9.5)
Top Groups
1 Booze Design  (9.3)
2 Nostalgia  (9.3)
3 Oxyron  (9.3)
4 Censor Design  (9.3)
5 Crest  (9.3)
Top Graphicians
1 Sulevi  (10)
2 Mirage  (9.8)
3 Lobo  (9.7)
4 Mikael  (9.7)
5 Archmage  (9.7)

Home - Disclaimer
Copyright © No Name 2001-2024
Page generated in: 0.059 sec.