On 66MHz mainboards most vendors used 12nS TAG chips (and 6nS or 7nS SRAMs). In case of any stability issues that don´t occur with 60 or 50 MHz FSB or if you´re going to overclock you might go for 12nS chips.
(In an ideal world 12nS TAG chips should be capable of operating at up to 75 MHz.)

majestyk wrote on 2022-06-23, 20:17:

On 66MHz mainboards most vendors used 12nS TAG chips (and 6nS or 7nS SRAMs). In case of any stability issues that don´t occur with 60 or 50 MHz FSB or if you´re going to overclock you might go for 12nS chips.
(In an ideal world 12nS TAG chips should be capable of operating at up to 75 MHz.)

I looked into which I should use and I noticed socket 7 boards seeming to mix and match. So I didn't think that would matter. I'll keep an eye out on ebay for a 12ns tag chip (I already have one from the board originally)

Good news, my cpus arrived today!

I also ordered a Chinese ati rage xl, could be fun to modify.

CalamityLime wrote on 2022-06-28, 12:04:

Good news, my cpus arrived today!

I also ordered a Chinese ati rage xl, could be fun to modify.

Keep an eye out for radeon 7500s they work well in these. But the rage xl aside from needing 3.3v mods might be a nice fit for the build. Though not as fast.

I finished taking my RTC chip apart I was surprised to see a PCB mounted on top of the vt82885n chip

It's quite cool seeing it in bits like that. I was curious about the caps on the crystal and the datasheet for the vt chip mentions needing 2 10 pf caps

CalamityLime wrote on 2022-06-29, 00:48:

I finished taking my RTC chip apart I was surprised to see a PCB mounted on top of the vt82885n chip

It's quite cool seeing it in bits like that. I was curious about the caps on the crystal and the datasheet for the vt chip mentions needing 2 10 pf caps

Oh wow. I’ve never seen one fully dissected.

Sphere478 wrote on 2022-06-29, 01:23:

CalamityLime wrote on 2022-06-29, 00:48:

I finished taking my RTC chip apart I was surprised to see a PCB mounted on top of the vt82885n chip

It's quite cool seeing it in bits like that. I was curious about the caps on the crystal and the datasheet for the vt chip mentions needing 2 10 pf caps

Oh wow. I’ve never seen one fully dissected.

Yeah, I found that a blast of a blow torch lighter made the epoxy soft like butter, so I just cut it off with a hobby knife.

and rebuilt with a cr2032 because why not.

I didn´t know they put the RTC chip in an additional socket. Why did they do that?

Oops - the socket is DIL28 instead of DIL24, so I guess you just used it for the soldering.

majestyk wrote on 2022-06-29, 05:02:

I didn´t know they put the RTC chip in an additional socket. Why did they do that?

Oh that was me. I done that so I wouldn't break the legs of the chip while handling it.

Good idea, the legs get bent easily and could break while working on the circuit.

You will have done a lot of work and modifications before switching on the board for the first time, so I hope eveything works right away. If it doesn´t you never know weather the board come with some defect or if you built in one yourself.
But I honestly admit I do it the same way when restoring old hardware.

Also, question,

What is this pin?

A datasheet says that it's a d42 data pin but the socket doesn't have a hole for it. I saw that Tillamooks have that extra pin but I didn't know that extended to ceramic pemtiums. The motherboard has a hole for the pin but the socket does not.
The k6 I ordered fits just fine, is that pin even required? can I drill a hole in the socket and ignore the pin entirely?

majestyk wrote on 2022-06-29, 05:15:

Good idea, the legs get bent easily and could break while working on the circuit.

You will have done a lot of work and modifications before switching on the board for the first time, so I hope eveything works right away. If it doesn´t you never know weather the board come with some defect or if you built in one yourself.
But I honestly admit I do it the same way when restoring old hardware.

I haven't really modded the board yet. I have mods planned and some pcb's ordered but the tag ram mod is not implemented, vrm mod is not implemented,
The only committed mods are some new caps to replace ones around the cpu, the RTC, changed the keyboard connector because the old one was destroyed and I wanted to make a foot print based off of it and the two wires I soldered to the chipset. The resistor is still in place and I planned on booting it the first time with the original tag ram because trying the mod.

Just checked some socket 7 boards - the pcb has it, the socket 7 socket doesn´t.
Is this an early Pentium MMX (P55C) or a P54CS Pentium-S?
With 2.8V Vcore it´s supposed to be P55c...

majestyk wrote on 2022-06-29, 05:28:

Just checked some socket 7 boards - the pcb has it, the socket 7 socket doesn´t.
Is this an early Pentium MMX (P55C) or a P54CS Pentium-S?
With 2.8V Vcore it´s supposed to be P55c...

P55C yeah

had to check it on cpu world
https://www.cpu-world.com/CPUs/Pentium/Intel- … 0A80503166.html

Just noticed Socket 7 does have this hole, not as a single hole but in it´s 5th row of pins that it has at all 4 angles. Older Pentiums only have 4 rows of pins at 2 angles and this one single pin in the 5th row. But they still fit Socket 7.
Some mainboards have an additional pin there in the 6th row also.

Your SL27K has 4 rows at two angles and one pin in row 5, so it should fit socket 7 and socket 5.

Okay, what took me a long time to see.

Yeah the left and right of the socket has an extra row of holes than the cpu has pins.

I was really confused since it felt like that one pin was stopping the cpu going into the socket but it just needed a good push. Especially confusing since the k6 just fell into the socket with little pressure.

Sorry for being an idiot.

majestyk wrote on 2022-06-29, 05:41:

Just noticed Socket 7 does have this hole, not as a single hole but in it´s 5th row of pins that it has at all 4 angles. Older Pentiums only have 4 rows of pins at 2 angles and this one single pin in the 5th row. But they still fit Socket 7.
Some mainboards have an additional pin there in the 6th row also.

Your SL27K has 4 rows at two angles and one pin in row 5, so it should fit socket 7 and socket 5.

yes, what you said 🤣

man that was very confusing. now I'm wondering what the extra hole in the motherboard is about.

Some socket 7 pcbs have this 6th row hole some don´t - maybe this was due to some planned socket 7 evolution that never happened. It´s often the case that the layout of a mainboard already anticipates changes that were introduced later. Sometimes this is good for us today so we can add some features by adding components.

I got the board installed on the motherboard back plate
It took some inventive thinking to get screw holes to align, had to do something since the board was just clinging on by the skin of it's teeth before