REU for C-64 & C-128

Disk drives, Monitors, SuperCPU etc.
dudz
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Re: REU for C-64 & C-128

Post by dudz » Thu Aug 13, 2015 9:40 pm

if you are serious about REU stuff, look at wolfgangs reference _only_ - all other documents have errors somewhere (eg the "reu size" bit is documented wrong almost everywhere else)



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Re: REU for C-64 & C-128

Post by motrucker » Tue Aug 18, 2015 5:13 pm

dudz wrote:if you are serious about REU stuff, look at wolfgangs reference _only_ - all other documents have errors somewhere (eg the "reu size" bit is documented wrong almost everywhere else)
I can't find this one - Could you please post a link to it?
C-64, C-128, and Amiga A2000 user

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Re: REU for C-64 & C-128

Post by dudz » Tue Aug 18, 2015 5:47 pm

try looking 3 posts ago ^_^

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Re: REU for C-64 & C-128

Post by maraud » Thu Aug 20, 2015 7:47 pm

eslapion wrote: Strange... never had that problem.

What firmware do you have in there? Also, did you download firmware updates?
Ah heck I don't remember, it's not a problem anymore, was a problem a ways back.

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Re: REU for C-64 & C-128

Post by Nonefornow » Fri Aug 21, 2015 5:26 pm

Oh, here is where the conversation regarding the REU is continuing - :D :D :D
eslapion wrote:@Tachyon:
I have yet to find a single piece of software which doesn't work well with the 1541 Ultimate I's integratd REU so IMHO, complaining that "it's not 100% compatible" simply indicate sceners and demo coders have way too much influence in the Commodore community.
In any case here are my thoughts -

I am not sure what we define 100% compatible since C= never made a 16MB REU. As far as I can tell the only REU that had 16MB was the RAMLink by CMD. I do not know if the 1541U-II is compatible to that.

Except for GEOS (and its derivatives gateway, wheels, etc.) there was very little software that needed an REU. I would say no other software. Unless someone can present a title.
Sceners and Demo coders have in facts exploited its usage. As of now, I personally do not have much interest in demos, but regardless, if the majority of users that need a 16MB REU are demo coders, then it would be logical that their influence should be taken into consideration.

In respects to GEOS, as far as I can tell, the most current "Config" driver is set to use only up to 2MB. However, I noticed that if the 1541UII is set to 16MB GEOS does behave erratically. In may experience it actually makes copying into the RAM disk slower. Also I noticed a GEOS slowness compared to the C1750. However for my usage I like the RAM drive to emulate the C1581 - hence the need of 2MB.

I would and could use a 16MB "cycle exact" REU only device.

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Re: REU for C-64 & C-128

Post by maraud » Fri Aug 21, 2015 8:41 pm

Nonefornow wrote:O
Except for GEOS (and its derivatives gateway, wheels, etc.) there was very little software that needed an REU. I would say no other software. Unless someone can present a title.
The vast majority of BBS software used the REU as a way to speed things up (rather than loading the modules from disk). I also use it frequently with ZED on my 128.

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Re: REU for C-64 & C-128

Post by eslapion » Sat Aug 22, 2015 12:30 pm

@Nonefornow:
First, no, the RAMLink and Commodore's REU don't operate in the same way at all.

When you plug in the RAMLink, you immediately get access to a storage device with the amount of storage equivalent to the amount of RAM installed.

Commodore's REU is a DMA device with no firmware that requires software to give it commands to start doing something.

My point of view concerning the REU is quite different from yours. Demo coders have a tendency to consider only what they want for themselves and even openly claiming nobody is going to tell what to do and what not to do and the consequence is many very nice demos only exist either only for PAL or only for NTSC.

For a time in the late 1980s mostly, software companies had a tendency to do that to and the result was that a lot of software for the C64 didn't work on the C128 in 64 mode or on the 64c. Back then this wasn't a problem with the REC because there was no emulation or compatible device; even CMD's 1750 clone in fact used Commodore's REC chip.

Of course, the people who created these software tried as much as they could to give a ton of flame to Commodore for supposedly making false claims about the 100% compatibility level of the C128, 1571 and 64c. They were losing business and getting numerous angry customer calls.

At first, the people at Commodore listened and thought they might have missed something important. When they realized the problem was with companies or individuals exploiting undocumented features, illegal opcodes and outright bugs from chips, they changed direction completely. They intentionally made the 8500 CPU incompatible with many illegal opcodes of the 6510, redesigned the 856X HMOS VIC-II chips specifically not to support a number of undocumented features and "useful bugs". They also systematically ignored any communication related to problems caused by software not "following the rules". The official answer was: if its not in the C64 programmers' reference guide then officially, it doesn't exist. If you lose money or get flamed because you used it anyways then go F**K yourself.

IMHO, Gideon created an REC which follows to the very letter the documented capabilities of the REC. If a jacka55 starts whining because he/she exploited undocumented features or bugs of the REC and now his software won't work with a new REC then this person can just bury him/her self.

Demo coders couldn't be bothered when people are unhappy with demos not existing in the other video standard or because they are incompatible with the 65C02 installed in some 1541 drives. If they don't listen to us then we shouldn't listen to them - just like Commodore indirectly said back then... do it right or go extinct.
Wealth, like happiness, is never attained directly. It comes as a by-product of providing a useful service. -Harland D. Sanders

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Re: REU for C-64 & C-128

Post by dudz » Sun Aug 23, 2015 11:42 am

Except for GEOS (and its derivatives gateway, wheels, etc.) there was very little software that needed an REU. I would say no other software. Unless someone can present a title.
while it's true that it wasnt used much, there actually were quite a bunch of utilities that used it (mostly copy programs). and even a couple of games (the infocom interpreter and test-drive2 iirc)
software companies had a tendency to do that to and the result was that a lot of software for the C64 didn't work on the C128 in 64 mode or on the 64c.
in fact, the number one reason for pretty much all C64 software that doesnt work on a C128 is an accidental write to $D030 that enables 2MHz mode. - And while doing that isnt "nice" programming practise, its 100% correct and non harmful according even to just the published and official VIC-II features.
They intentionally made the 8500 CPU incompatible with many illegal opcodes of the 6510
actually, no they didnt.
redesigned the 856X HMOS VIC-II chips specifically not to support a number of undocumented features and "useful bugs".
no, they didnt.
Infact, CBM put _huge_ efforts into making the C128 as C64 compatible as possible. Ask bill herd if you dont believe it.

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Re: REU for C-64 & C-128

Post by Nonefornow » Fri Dec 04, 2015 9:22 pm

eslapion wrote:@Nonefornow:
First, no, the RAMLink and Commodore's REU don't operate in the same way at all.
Exactly right - and that is precisely why the terms "100% compatible" are a little unclear to me. I guess "cycle exact" probably is a better fit.

In any case does anyone know if this project is still ongoing or not?

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Re: REU for C-64 & C-128

Post by eslapion » Fri Dec 04, 2015 11:17 pm

@Nonefornow
No clue at all. However, a few years ago, I purchased a VHDL model of the REC for static RAM similar to the one used in the 1541 Ultimate II from Gideon Zweijtzer.

I should be able to implement it in a XC95288XL. Of course there are naysayers who claim this model isn't completely cycle exact. However, apart from a couple of demos, I don't know of anything that has problem with the REU emulation implemented in the 1541 Ultimate I or II.
Wealth, like happiness, is never attained directly. It comes as a by-product of providing a useful service. -Harland D. Sanders

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