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Old 03 March 2020, 19:26   #1
rmadden
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Upgrading GVP A1230 Turbo+

I'm thinking of upgrading my GVP accelerator from a 68ec030 (40mhz) to a full 68030 at 50 mhz. In addition to the 030, it has a 68882 fpu running at 40 mhz. It also has 8 MB RAM.

The question I have is ... if I upgrade the processor to a 50 mhz chip, do I also need to upgrade the fpu to 50 mhz as well? I also read something about the oscillator, which is set at 40 mhz. Would this have to be upgraded as well? If these parts do need to be replaced, what others are there that I need to consider.

I've read some other posts on this site as well as searched on-line for answers but can't really find them.

I appreciate any information.
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Old 03 March 2020, 20:09   #2
SpeedGeek
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You should get a 50 MHz 030 (but I doubt you will reach this clock speed with any practical stability). You can just over clock the 68882 and it should work just fine.

Now, I really don't want to spoil your over-clocking project, but I do suspect the Fast RAM will fail before you reach 50 MHz. But 44-45 MHz should at least be possible so please continue and report back with your results.

Good luck!
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Old 03 March 2020, 20:49   #3
rmadden
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My goal isn't to overclock anything. What I'm really trying to do is replace the 030ec with a non-ec chip. I've seen a couple of 40 mhz chips on ebay but, the majority of chips are either 33 mhz or 50. If the 50 mhz chip will burn out the RAM, then will dropping to 33 be beneficial?

The reason I'm even considering this is that I purchased OS3.1.4 and, according to the GVP-read.me file:

"The 68030 CPU suffers from the CIIN bug. This bug permits the CPU to
ignore the Cache Inhibit hardware signal from the memory bus when it
writes a 32-bit longword to RAM. The result is a cache entry is
allocated for the write, and if (usually compiled) software attempts to
read the written location soon after, a cache hit could occur, resulting
in bad (stale) data if the written location is shared RAM or an I/O
register. The MMU can mitigate this bug (SetCPU FastROM, or MuLibs
68030.library), however the latter option is the only option for the
68EC030. This results in the <16MB range to not be Data Cached. For
this reason, G-Force 68030 boards with 68EC030 CPUs should consider
placing most/all of the 32-bit RAM in the high-mapped address range. if
possible. Replacing the PGA 68EC030 CPU with a full 68030 is also an
option."
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Old 03 March 2020, 21:37   #4
indigolemon
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I would think you should be able to run a 50Mhz part at the boards native 40Mhz.

Although from the readme excerpt above, I'd just install the MMULibs package and use the 68030.library it provides.
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Old 03 March 2020, 22:16   #5
Higgy
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Hi.

I have a Jaws 2 (turbo+2).
For the CPU and FPU to run at 50Mhz you need a 50Mhz crystal. The crystal dictates the speed.

I am sure the Jaws 1 and Jaws 2 memory are the same and Jaws 2 can run at 50Mhz (also from factory at this speed) so I dont see a problem with memory.

I upgraded my Jaws 2 from EC 40Mhz to full 50Mhz. My FPU is still original 40Mhz so it is now overclocked. I used a Freescale Rev C 030 gold top. It is marked 25Mhz but i read the CPU mask of the last rev chips is same as 50Mhz anyway. Production yield improves towards end of life, so easier just to make 1 chip and just label them different speeds.

The other day I just got a Freescale 68882, it is rated 16Mhz but seems to run fine on my Blizzard 1230 Mk1 at 40Mhz. Again once the chip production is mature and yields are good why make different chips for different speeds.

The Terrible Fire CD32 030 accelerators that are sold quite often have Rev B 030 plastic top 40Mhz, but they are running at 50Mhz fine. My Terrible Fire is using my original Jaws 2 Rev B 40Mhz fine.
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Old 03 March 2020, 23:29   #6
rmadden
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Thanks for the replies.

Higgy, If I read you correctly, if I don't replace the crystal, the cpu will run at 40 mhz, right? If this is the case, then SpeedGeek's prediction of burning out the RAM shouldn't arise. I've had this card for a long time ... I don't want to damage it, just upgrade it.
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Old 04 March 2020, 00:39   #7
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Quote:
Originally Posted by rmadden View Post
Thanks for the replies.

Higgy, If I read you correctly, if I don't replace the crystal, the cpu will run at 40 mhz, right? If this is the case, then SpeedGeek's prediction of burning out the RAM shouldn't arise. I've had this card for a long time ... I don't want to damage it, just upgrade it.
No, I did NOT predict you would burn out the RAM. I simply predicted the RAM would become unstable at 50 MHz. There are apparently a least 2 revisions of this accelerator card... Hence, your mileage will vary.

My experience with 030 over-clocking was that 25, 33 and 40 MHz units could reach 50 MHz but the RP package imposes a practical limit of 40 MHz due to heat dissipation issues. The RC package handled 50 MHz quite well.

BTW, the CIIN feature/cache bug is over-rated. It may cause a problem for Bridge Boards or poorly designed I/O Boards but most 030 systems never experience any noticeable problems with it.
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Old 04 March 2020, 05:38   #8
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Thanks Speedgeek, but there's a bit of a distinction between "unstable" and "fail".
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Old 04 March 2020, 17:39   #9
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Quote:
Originally Posted by rmadden View Post
Thanks Speedgeek, but there's a bit of a distinction between "unstable" and "fail".
Oh really? ...and apparently there is no distinction between "Fail" and "Burn Out"?
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Old 04 March 2020, 22:11   #10
Higgy
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Quote:
Originally Posted by rmadden View Post
Thanks for the replies.

Higgy, If I read you correctly, if I don't replace the crystal, the cpu will run at 40 mhz, right? If this is the case, then SpeedGeek's prediction of burning out the RAM shouldn't arise. I've had this card for a long time ... I don't want to damage it, just upgrade it.
Correct. The processor could be stable 25-50Mhz, but the crystal dictates the speed.
Think like a car. It could do 100mph but you need to push the accelerator to do the speed. The crystal is like a hard speed limiter.

the Turbo+ and Turbo+2 ram modules might be exactly the same. Thus completely fine at 50Mhz. But yes there might be board differences between Turbo+ and Turbo+2 which makes Turbo+ unstable at 50Mhz. You could always write down your ram chip markings and I can look at mine.
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Old 05 March 2020, 01:25   #11
rmadden
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Quote:
Originally Posted by Higgy View Post
Correct. The processor could be stable 25-50Mhz, but the crystal dictates the speed.
Think like a car. It could do 100mph but you need to push the accelerator to do the speed. The crystal is like a hard speed limiter.

the Turbo+ and Turbo+2 ram modules might be exactly the same. Thus completely fine at 50Mhz. But yes there might be board differences between Turbo+ and Turbo+2 which makes Turbo+ unstable at 50Mhz. You could always write down your ram chip markings and I can look at mine.
Thanks Higgy,

The first chip markings are: ais-mB9 94v-0 HD64PIN
The second chip markings are: SIM 32-4MB-60 9312 USA

I appreciate it!
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Old 07 March 2020, 10:50   #12
Higgy
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Here are the chip markings:

SEC KOREA
649Y
KM44C4000AS-6
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Old 07 March 2020, 11:39   #13
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Yeah go ahead and run the 50Mhz CPU at 40Mhz, it should work just fine and as a side benefit it should run cooler than a real 40Mhz part. As mentioned, the cache bug shouldn't be an issue anyway, but with the MMU you'll get the added benefit of being able to use MMU-related stuff like dirty-page-only graphics drivers (e.g. in Shapeshifter) and clean memory mapping if you plug in a Mediator.
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