VOGONS


First post, by arnovdheiden

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Hello,

I'm Arno van der Heiden from Netherlands, and I'm working on a retro pc build using a Asus P55TVP4 Socket 7 mainboard and an Pentium 1 233 mmx processor. I combine a S3 Virge DX and a Voodoo 1 for graphics, and a Promise Sata300 controller for an SSD for storage. A Vibra 16 sound card with OPL chip for sound, and a Intel Pro 1000 GT for networking. All together in a nice old Escom AT housing.
Sadly the battery of the RTC chip died after 20+ years, so i ordered a new one on ebay. I am okayish (not that great) with soldering, so I hope to be able to solder off the old chip and solder on the new chip. I was reading about the low voltage mobile Pentium MMX processors. The 266MMX and even the 300MMX. They have a clock multiplier of 4 and 4,5 on a 66MHz bus.
My current 233MMX has a multiplier interpretation that translate sa multiplier of 1,5 to 3,5

I have 2 questions maybe some of you know the answer.
1. is replacing the RTC chip as simple as it sounds? Just off the old one and on the new one. Isn't any special activation needed to get the new chip to work?
2. does the tillamook 266MMX and 300MMX have the same multiplier interpretation as the 233MMX? So 2.0 becomes 4.0 and 2.5 becomes 4,5? I wonder, because the 300 would be a nice upgrade, if available as PGA.

Thank you so much for reading this, and thinking along.

Best regards,

Arno van der Heiden

Reply 1 of 11, by Doornkaat

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Welcome!
The clock chip replacent is as easy as desoldering the old part and dropping in a new compatible part. Soldering a large IC like that may pose a challenge to a soldering novice though so be prepared for some frustration. 😉
There's also a common hack to replace the internal RTC battery with a CR2032 holder. Doing this will make you independent of the supply of new RTC modules.
There is no special activation needed after swapping the RTC module but it won't hurt to clear your CMOS settings and restore BIOS defaults after swapping in a new RTC.

I'm not sure about the Tillamook CPUs and their multipliers, sorry. You can mod your CPU or socket to have the position of the BF2 pin permanently shorted to ground, effectively permanently setting a BF2 jumper on a board with only BF0 and BF1. But really I wouldn't do this and instead switch to a faster platform altogether if I felt my Pentium MMX system wasn't fast enough for what I was using it for.
The CPU can be modded in the same way btw. so maybe that's actually what Intel did on the faster Tillamook cores but I'm totally just speculating now.

Reply 2 of 11, by H3nrik V!

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Regarding using Tillamook, it's not necessarily that simple; this thread will give some insights to that Tillamook 266MHz and working L2 cache?

Please use the "quote" option if asking questions to what I write - it will really up the chances of me noticing 😀

Reply 3 of 11, by waterbeesje

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Replacing the Dallas clock or similar will probably work, but most of the "new" ones already are 1/2 to 3/4 drained. New old stock is great, but batteries still show their real age and these just drain.

Whenever I find the Dallas chip I go for the mod. If soldered to the board, I use tape to secure the area for dust and do this in place, much easier than desoldering.

If you do replace the Dallas: do yourself a favour: solder in a socket and place the new Dallas into the socket. Next time it's drained (could be sooner than you'd like), you'll be thankful to yourself 😀

Stuck at 10MHz...

Reply 4 of 11, by amadeus777999

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waterbeesje wrote on 2020-09-15, 12:21:

Replacing the Dallas clock or similar will probably work, but most of the "new" ones already are 1/2 to 3/4 drained. New old stock is great, but batteries still show their real age and these just drain.

Whenever I find the Dallas chip I go for the mod. If soldered to the board, I use tape to secure the area for dust and do this in place, much easier than desoldering.

If you do replace the Dallas: do yourself a favour: solder in a socket and place the new Dallas into the socket. Next time it's drained (could be sooner than you'd like), you'll be thankful to yourself 😀

x2 + use a desolder gun if you're not skilled - you may eff up your board big time.

Reply 5 of 11, by maxtherabbit

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waterbeesje wrote on 2020-09-15, 12:21:

Replacing the Dallas clock or similar will probably work, but most of the "new" ones already are 1/2 to 3/4 drained. New old stock is great, but batteries still show their real age and these just drain.

That's just not true. The new ones from Digikey are 100% capacity. If you buy random NOS from ebay or something, maybe

Reply 6 of 11, by arnovdheiden

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Hello all,

Thank you so much for your reply. I have a desolder gun, so that's wat I was planning to use to get the chip off. I think the plan of using a socket is a good one. I am just not sure where to find/order the right one. I hope some of you might have a link to the right socket so i have the right one right away 😀. I think it's the best way to replace it like that. It looks best, and it's easy to change it after. The method of attaching a CR2032 holder to the chip is of course an idea, but i prefer the socket approach. If it's drained again, I just replace the whole thing again.
My soldering experience is on the level of replacing elco's on dead TFT PSU's, and it worked everytime. So I will just take my time for this one and make the best of it.

If anyone has the modelnumber or name of this socket, I would really appreciate!

Best regards, Arno van der Heiden

Reply 8 of 11, by waterbeesje

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I don't know the exact part number, but these can be ordered from many sites, like Mouser, Jameco or AliExpress.

I came across this trc on Jameco:
https://www.jameco.com/z/DS12887--Dallas-Semi … yte_133452.html

I know, you want the socket. This site does give you a datasheet, and on page 20 you can find the dimensions for the dip24 socket.

Groetjes!

Stuck at 10MHz...

Reply 10 of 11, by arnovdheiden

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an update about my project.
As I said, I ordered the 24pin wide dip socket, and a new (ish) compatible dallas RTC chip. I received it several weeks ago, but i wanted to find the perfect time and energy to work on it.
I managed to solder of the old chip, but it cost me a lot of patience and frustration, but at the end i succeeded to get it off. Some of the holes went closed or not open enough, so it was difficult for me to get them open again, but i managed to get it done anyway. Took me extra time because I don't have the right tools to do it the easy way. After that I inserted the dip socket and soldering the pins of the socket to the mainboard was relatively easy. After succesfully soldering the dip socket to the mainboard I inserted the "new" dallas chip into the socket, without bending any pins (phew..). after building it back into the case the big moment was there.
I switched on the computer, and the relieving post beep was there. The motherboard was still alive! Yes! After saving the bios defaults I rebooted, and the cmos error message was gone. I succeeded!!
I am very happy and want to thank you all again for helping me getting me on my way with this.

Best regards, groeten, Arno

Reply 11 of 11, by waterbeesje

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That's great! I know it can be a hassle to get things out of the pin count is over four... Better tools would be the answer but that's a little investment that you could consider. My soldering iron is ok-ish for thru hole but for smd almost worthless. And of course getting more and more experience will help.

For now you can go on for a few years again with the new Dallas 😀

Stuck at 10MHz...