Posted By
Dan7
on 2021-12-20
06:07:43
|  CPU replacement vs Bauknecht games
I'm facing an issue that might have been discussed here already, but I did not find a clear solution even after checking through some related threads: This year I purchased a refurbished C+4, with internal SD2IEC and replaced CPU already installed, ready for gaming.  However, after re-discovering all the childhood classics and some more recent excellent releases, I ran into the following problem: most of the Bauknecht games (Alpharay, Slipsteram, Pets Rescue, MOS...) simply hang after starting. My first guess was the SD2IEC (old version), so I replaced it with a Pi1541, but the problem remained. My second guess now is the CPU replacement, and especially that the KERNAL version is colliding with Krills/Bitfire loaders, but being a newbie, I'm not sure how to proceed (also, I do not have an original CPU for testing). Should I just buy another CPU replacement kit (as I'm not sure of the origin and version of the current one in my machine) or is there a simpler potential solution? Any advise is welcome.
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Posted By
Doug
on 2021-12-20
06:28:54
| Re: CPU replacement vs Bauknecht games
I'm sure you'll get a definitive answer from someone on here, but I'm pretty sure that SD2IEC is not compatible with fast loaders.
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Posted By
MIK
on 2021-12-20
07:32:27
 | Re: CPU replacement vs Bauknecht games
Yeah the original Pets Rescue was designed to make use of the 1551 floppy drive. Thankfully the guys later released a version for SD2IEC which can be found on the games page.
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Posted By
MCes
on 2021-12-20
07:52:23
 | Re: CPU replacement vs Bauknecht games
@Dan7
Could you post some pics of this CPU replacement?
Your issues can be compatible with a C-Mos 65C02 core that can't manage the illegal opcodes....
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Posted By
siz
on 2021-12-20
09:09:47
| Re: CPU replacement vs Bauknecht games
My guess would be a 6510 based CPU replacement with patched KERNAL. That works fine until you want to use a custom loader. If that's the case try to find an original 7501/8501 CPU or a 6502 based replacement. Both will require original (or switchable like JiffyDOS) KERNAL.
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Posted By
Mad
on 2021-12-20
11:11:03
| Re: CPU replacement vs Bauknecht games
Hi Dan7.. Our games use two different loaders..
Alpharay, Pets Rescue are using Bitfire (1551 + 1541)
Slipstream, Mos, Lands of Zador are using Krills Loader (1541 only)
CarTed is a single file game
There are some demos done by us which are using Krills loader too.
For the game Mos and Lands of Zador you also can select Kernal Loading (Fastloader=no) at start which should run with any connected drive type.
The games Pets Rescue and Alpharay do also have some SD2IEC versions here in the database which where reported to run well on several SD2IECs already.
If none of these games work (even MoS with Fastloader=OFF) then I would strongly suspect that it has nothing to do with the loaders at all.
I remember some threads about CPU replacements here which don't support illegal opcodes. We ( I ) heavyly rely on illegal opcodes. Actually it's mostly the opcode "LAX" which is not a standard 6502/6510 opcode.
An easy try would be CarTed if it runs then it's not the illegal opcodes but if it fails then it almost clearly is the usage of the illegal opcodes which aren't supported by the CPU replacement.
But anyhow I think other people would use these opcodes too (it's pretty common to use them in demos for instance), so maybe that is not the explanation for the problem, but at least worth a try. It's strange that all the game fail even with 3 different loading systems so it seems it's not the loader at all.
And I remember Krill saying that just one drive may be connected at once for his loader to load.. Maybe it's the same for all loader types.. Maybe you got several drives connected at once? But I think then at least sizs ioLib for the SD2IEC versions of Alpharay and Pets Rescue should not fail.. And Kernal Loading of Mos and Lands of Zador should also do it's work..
Hope we get that fixed..
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Posted By
MCes
on 2021-12-20
10:15:48
| Re: CPU replacement vs Bauknecht games
The 6510 mod support illegal opcode but can't support custom loaders....
A 6510 cpu has a different bits implementation into own port, so the SW has to be patched: the kernal has to be modified.
The problem is that the custom loader, as the original kernal, try to use the CPU port respecting the traditional bits map, so they fail.
If you have a real 1541 try it.....
I used an adapted CPU 6510 (not a great solution, but to check if the machine starts is ok...) ant it can work also with disk turbo loader using a.... 1551 unit! (because it's connect to bus with a cartridge, not to the serial bus: the CPU port is not used for this!)
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Posted By
Dan7
on 2021-12-20
10:57:53
| Re: CPU replacement vs Bauknecht games
Thank you all for the quick answers, very supportive community indeed
@Doug: The SD2IEC was also my first suspect, but to my greatest disappointment the Pi1541 produced exactly the same issue. Luckily my all-time favorite "The Pit" runs well on both devices so I was not left without entertainment  (Not too relevant here but the music of Icicle Works got me really hooked on the +4 as a child, what a masterpiece!)
@Mik: Tried Pets Rescue's both versions on both devices, none of them worked 
@MCes: Yes, I assume that the problem comes from the issue you mentioned, I'm just not sure what is the most practical way ahead to solve it. Picture of the replacement will follow soon.
@siz: Indeed, the major suspect now is the 6510 based CPU replacement with patched KERNAL. I'm just wondering if there's any other solution than replacing both the CPU and the KERNAL.
@Mad: Some surprises here: CarTed is running well, MOS and Zador starts up with the Fastloader=no option but then crashes during the game, with Slipstream I can get through to the intro, but it crashes as soon as I'm starting the game. Alpharay and Pets Rescue would not even boot up. Currently I'm testing all these with Pi1541, the SD2IEC is disconnected.
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Posted By
MCes
on 2021-12-20
13:24:07
| Re: CPU replacement vs Bauknecht games
@Dan7
" Indeed, the major suspect now is the 6510 based CPU replacement with patched KERNAL. I'm just wondering if there's any other solution than replacing both the CPU and the KERNAL."
have a look at point 9 and 10: https://plus4world.powweb.com/forum/38827
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Posted By
siz
on 2021-12-20
13:17:20
| Re: CPU replacement vs Bauknecht games
@siz: Indeed, the major suspect now is the 6510 based CPU replacement with patched KERNAL. I'm just wondering if there's any other solution than replacing both the CPU and the KERNAL.
The 6510 CPU has a different built-in I/O port which is not compatible with the one in the 7501/8501. With KERNAL patches it's usable for stuff using standard KERNAL routines. But as soon as you want to have something with custom loaders (like disk based games and demos) it won't work. You HAVE to replace both your CPU and KERNAL.
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Posted By
gerliczer
on 2021-12-20
13:25:13
| Re: CPU replacement vs Bauknecht games
@siz: It was quite interesting to see that he managed to read only the first half of your first reply. The second half was the solution to his next question.
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Posted By
MMS
on 2021-12-20
16:47:23
 | Re: CPU replacement vs Bauknecht games
If I summarize: the 6510 should be OK with kernal loader (=no fastload)?
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Posted By
Mad
on 2021-12-20
17:37:36
| Re: CPU replacement vs Bauknecht games
Actually I do think that it should be ok.. I don't remember doing any port related stuff within the games. It's strange that it even crashes without the loaders attached.. But there must be something odd, because all classics are running well it seems..
edit: KERNAL has to be patched with 6510 but I assume this is already done.
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Posted By
marcos64
on 2021-12-21
04:05:07
| Re: CPU replacement vs Bauknecht games
I have similar problems with these games and a CPU replacement. They work, but sometimes they hang while loading.
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Posted By
Dan7
on 2021-12-21
06:39:49
| Re: CPU replacement vs Bauknecht games
Thank you again for all the comments, especially for gerliczer
It's clear now that in the current setup my machine will not handle these games, so I opened it up and checked the CPU replacement kit that was used. Unfortunately there's no visible writing at all on either the replacement board itself or the KERNAL (so a photo would not make much use). Even worse, the kit is somehow glued onto the motherboard so I cannot remove it without applying some force, which I don't want to risk as I may break something else during the process. So after some consideration I decided to leave the machine as it is and just enjoy that it runs all my favorites.
@Mad: As you wrote, "Alpharay, Pets Rescue are using Bitfire, Slipstream, Mos, Lands of Zador are using Krills Loader" > the first two hangs immediately, while the latter three starts up at least, so the issue must be something with these loaders. In the end at least we learned something from this exercise
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Posted By
Doug
on 2021-12-21
08:18:25
| Re: CPU replacement vs Bauknecht games
If "The Pit" is working OK then that's strong evidence that the illegal opcodes are OK. I make (ahem) significant use of them
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Posted By
Dan7
on 2021-12-21
10:04:46
| Re: CPU replacement vs Bauknecht games
"The Pit" is working brilliantly well, now I'm on the 20th level. Do you _maybe_ know how many more levels can I expect before the game ends?
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Posted By
Mad
on 2021-12-21
10:16:17
| Re: CPU replacement vs Bauknecht games
marcos64 sad to hear that. But actually it's some problem with fast loaders then. Makes me a little sad, that this is not fixable at all. So a big sorry from me.
Dan7 So yeah seems to be not fixable at all.. :/ MCes wrote: "I used an adapted CPU 6510 (not a great solution, but to check if the machine starts is ok...) ant it can work also with disk turbo loader using a.... 1551 unit!" so maybe finding a 1551 would solve it. However if you are happy with your precious classics then no need to do anything then.. Another point would be to try the SD2IEC versions of these games. But you wrote you are happy without Alpharay and Pets Rescue so have a big time with your setup and the nice software you got!
Doug I didn't want to insult anyone.. It's just that there actually are people out there not using any of these opcodes. The Pit is such a technical marvel that I would of course assume some more fancy code there.
The Resource guys are pretty tough at using these opcodes, some demo effects by them do rather crazy stuff with these ones. (And they did Bitfire Plus/4 but I didn't look into the code for that yet, it has nothing to do with the opcodes anyways! )
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Posted By
Dan7
on 2021-12-21
10:40:00
| Re: CPU replacement vs Bauknecht games
@Mad: No worries at all, normally you are not expected to develop games for the +4 to be 6510 compatible. Also, I can (and will) try these games via emulator, and I'm sure to have some fun there. In the end I may consider to buy another +4 with an original CPU, you know, just to have a backup in case the current one breaks down...
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Posted By
MCes
on 2021-12-21
11:30:43
| Re: CPU replacement vs Bauknecht games
@Mad
@marcos64 already wrote about issues with some games,
forum/42161
and after the last CPLD revision (1321) that derived by that thread, the CPU4C16 and CPU4PLUS4 have better noise immunity, during a JIFFYDOS use, than the original CPU....
I tried with jiffydos the games that marcos64 pointed out to me and the same problems also occurred with an original MOS8501! The games incompatibility/instability are not with the CPU (original/replacement) but with the jiffydos kernal!
CPU4C16 / PLUS4(tape & Disk): there are no known problems with the turboloaders (if the machine is not modified) otherwise there may be problems between the turbo loader and the jiffydos routin, also with an original MOS8501.....
NOTE: my tests was done with physical 1541/1541 II, and PAL genuine JIFFYDOS
@Dan7
There is no charge to link some photos of your CPU replacement, and you made us curious ...
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Posted By
MIK
on 2021-12-21
11:13:43
| Re: CPU replacement vs Bauknecht games
Just in case, Yape is the preferred emulator for all C16/Plus4 needs by those in the know.
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Posted By
Doug
on 2021-12-21
13:18:42
| Re: CPU replacement vs Bauknecht games
@Dan7 level 20? Wow! That's some level of dedication!
There's still a long way to go - I packed in 37 levels. At least you're over halfway
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Posted By
Dan7
on 2021-12-21
17:38:44
| Re: CPU replacement vs Bauknecht games
@Doug OMG, 37 levels, and I was starting to be proud that "I almost finished it" It will definitely outlast the current holiday season, which I consider as good news!
@MCes, here I uploaded three pictures:
postimg.cc/FYs4pKkQ
postimg.cc/XBJPFrD2
postimg.cc/KkQVRPQk
You can see that whoever did this was not saving on the glue, even the KERNAL got some of it on the top. The whole thing looks very fragile in real life, I don't even dare to remove the 6510 as some of the soldering got already detached on the right side of the panel.
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Posted By
MIK
on 2021-12-21
21:43:10
| Re: CPU replacement vs Bauknecht games
Dan,
That Plus4's fav game must be Video Meanies as that chip setup is Nasty.
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Posted By
gerliczer
on 2021-12-22
02:34:32
| Re: CPU replacement vs Bauknecht games
@Dan7: Those pictures show that glue is used only to secure the 6510 to the interfacing PCB. The replacement might be possible to remove if it is done with extreme care. IDK if it is true for the KERNAL too.
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Posted By
marcos64
on 2021-12-22
03:32:23
| Re: CPU replacement vs Bauknecht games
I had the problems with JiffyDOS and with the standart kernal. And with the uIEC3 (SD2IEC) but also with the 1541 and 1541II.
But these games are not my cup of tea, so haven't tried them again. Something strange and subtle must be happening.
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Posted By
MCes
on 2021-12-22
10:40:11
| Re: CPU replacement vs Bauknecht games
@Dan7
Your PLUS4 can be easily recovered:
the kernal rom can be replaced without any kind of problem
(the glue is on top of new EPROM to fix a piece of paper to protect the erase window).
Your processor (6510) is connected to the motherboards socket (A) via adapter realized wiring together two sockets ("B"+"C").
It appear:
Chip 6510 can be removed from the ugly adaptor as normal.
The ugly adapter can be removed from the motherboard socket as normal.
At the end you will having the motherboard with its socket empty, an ugly adapter and a new CPU for a Commodore 64.
You need a kernal ROM and a working CPU 8501 solution....
(or you can do: "nothing" and enjoy playing with old games...)
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Posted By
Dan7
on 2021-12-22
19:18:02
| Re: CPU replacement vs Bauknecht games
@MIK: or the Tower Of Evil
@gerliczer: yes, I guess that the original intention was to glue together the two layers of the adapter, but the glue overflow a bit to the original CPU socket so the "tower" is fixed. Sure, I could very carefully "ease up" the contact, but I have no nerves/intention do do that for now. On the other hand, removing the KERNAL would be no problem.
@marcos64: now we can add to your list the Pi1541 as well
@MCes: thank you for the detailed explanation, but I prefer to keep it as it's now. A new original CPU is quite expensive and then I would still need an original KERNAL as well. Moreover, the machine runs perfectly not only the classics but most of the newer titles as well so there's not much incentive to take a risky adventure...
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Posted By
MIK
on 2021-12-23
05:12:29
| Re: CPU replacement vs Bauknecht games
Lol Tower of Evil, wish I thought of that one ha! 
Yep, as it is now you have a nice work horse any way!
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