Thinkpad 701cs Upgrade AMD 5x86 133Mhz

[Ghostdog]

Hello, has anyone had experience with replacing CPU on 701cs's board ? Did you have the problems with floppy drive and sound chip ?
I got freezes and reboots when trying to open a floppy. And also freezes if sound chip tries to play any sound. So I have to disable sound chip in BIOS to be able to start the Windows or disable all windows sounds.

[Ghostdog]

Could someone make some photos of a working modified motherboard, maybe I could compare them with mine and find out the difference.

[tfflivemb2]

I just quickly searched the forum, and found a pretty nice link that explains the upgrade and overclocking process, on the 701's:
https://blog.noq2.net/butterfly-on-spee ... z-mod.html

[Ghostdog]

Yes, I did all according to this guide. But it seems that this upgrade is not complete. People in the comments also had some problems, but with external display. They don't say anything about floppy drive or sound card. I didn't checked external display yet, maybe it will be also a problem.

If you check the last comment at the link below you will find a nickname badabumm who says that the upgrade in this article is not complete, but he doesn't give any details about how to make it complete.

https://hackaday.com/2014/10/21/thinkpa ... /#comments

Thus I think there should be done some more things.

[Ghostdog]

So no one can help me with photos of a modified TP701c board ?

[MooNWalker]

I do have an AMD 5x86 133MHz board, got it from the very same badabumm. But it's a lot of hassle to open up the machine to get to it. 701C(S) is probably the most difficult to disassemble/reassemble ThinkPad I've worked on.

The comments in the post mention heat, and mine does get quite hot after running for a while under full load, but manages to stay stable otherwise, with floppy and sound working fine. There is a heat spreader installed on my unit, did you install anything to manage heat on yours?

[Ghostdog]

No, I didn't install any heatsink on the CPU. Yes it's hot but I think it is acceptably. It doesn't freeze if I don't use floppy drive or sound card. It had been tested it in Quake for an hour or more. It's a pity that you don't have photos of your board, they could help me to find what else should be modified.

[MooNWalker]

No, I didn't install any heatsink on the CPU. Yes it's hot but I think it is acceptably. It doesn't freeze if I don't use floppy drive or sound card. It had been tested it in Quake for an hour or more. It's a pity that you don't have photos of your board, they could help me to find what else should be modified.

I think I might have some photos of it, but I'll need some time to dig them up if I do. Though they are likely of not high enough quality to see the specific elements on the board.

[Ghostdog]

Thanks, it would be something. I can't find photos of any quality in the Web.

[axur-delmeria]

Floppy and sound have something in common: a DMA channel. This leads me to believe that this is an issue regarding that. A quick search for "AMD 5x86 DMA" yields this forum post: http://www.vcfed.org/forum/archive/inde ... 11670.html. Quoting a relevant excerpt:

Additionally, there is some kind of problem related to am5x86 in that it will not cooperate with VLB SCSI controllers that use DMA while writeback cache is enabled. Setting the CPU to write-through will fix the problem though.

You could try setting the L1 cache to write-through and see if it helps.

[Ghostdog]

Thanks, I've already tried it, it didn't help. It only decreased CPU performance. Seems the problem with HITM# signal from CPU to Chipset it can also cause floppy problems.

[Ghostdog]

Played with chipset registers and three times somehow after modifying D6h register I've heard welcome music of Win98 but then it goes to reboot in few seconds. Not sure maybe it is coincidence. I have no more ideas, tried a lot of variants. The only hope is to get photos of modified motherboard. I'm even ready to offer some money for them