jamesbeat wrote:

I'm trying to build a machine that can be slowed down to replicate a 286, 386, 486 (and maybe a Pentium, though this is less important because I already have a Pentium Pro machine).
8088 would be awesome too, but I don't know if that's possible.

A smooth range from 286 to P1 is possible with Socket 5/ 7 boards with additional slowdown parameters, such as ultra low FSBs (33MHz or slower), forced Write-through L1 cache policy and Turbo/ De-turbo functionality.

Using a typical VIA C3 or SS7 K6 build won't slowdown into 286 territory. You might get better luck with a VIA C3 Nehemiah, but you lose smooth scaling.

Getting into 8088 territory is possible, too:
WIP 2: The 6-in-1 Turbo-switched Socket 7 - from XT to 500MHz; dual Tseng powered...

Scaling graphs:
download/file.php?id=33939&mode=view
download/file.php?id=34139&mode=view

There's only a few freak of nature socket 7 motherboards that can offer this capability, but it is nonetheless a very impressive result. Again, as I said before, in my experience, a C3 can skirt the upper edge of 286 territory (20 and 25 mhz Harris CPUs, for instance) as indicated by Norton SI and NSSI. For early x86 speed sensitive titles, though, I'm looking at a 386 build with tunable clockgen.

It's pretty much academic at the moment anyway - it looks like the correct C3 is going to take a little while to track down.

Tge good news though is that my new motherboard arrived today.

I got the Asus CUSI-FX, which is on the Via list of compatible motherboards.
Unfortunately no ISA ports, but it's a nice little board (flex ATX I believe).

I looked through my bag of ram and found a 64MB stick, and I also found a Mendocino Celeron to try the board out with.

I breadboarded it with a psu and a floppy drive and had a quick game of Prince of Persia.

I'm very pleased with it, and I'm glad I have a CPU to use it with until I track down a C3.

There are also a LOT of options in the BIOS, which was nice to see after all the OEM boards I've been using.

I'll have to try out those settings mentioned above, but it's bedtime now, so it will have to wait.

I'm sad to say that this one is going to have to go in a black case for now.

I'm not a fan of modern cases, but period correct beige cases are hard to find nowadays - I consider myself very lucky indeed to have found the five that I currently own.

Needless to say, I am always on the lookout for beige cases, so hopefully I will be able to rehouse it more appropriately in the future.

C3 CPUs are still cheap on ebay.

Check your PMs, James -- regarding tracking down a C3. Also I do love J^aws flex builds -- but they are pretty much impossible to build 😜 Aside from going out and buying massive amount of socket 7 boards and testing them all out there's no way of knowing if one has a functioning, legit turbo feature.

Yup, I got your PM and ordered one, thanks 😀

It was pretty expensive at $35 shipped, but considering how versatile it is, I'm happy with how much I paid.

The motherboard was $18 shipped, so the whole project had cost me a total of $53.

I lucked out last week and had access to three skids full of old machines at work before they were carted away for recycling.

I have a bunch of power supplies, memory, heatsink, fans etc. so no need to buy anything else for this build.

jamesbeat wrote:

It was pretty expensive at $35 shipped, but considering how versatile it is, I'm happy with how much I paid.

I could've sworn they had a Make Offer option -- I would have at least tried to offer less to compensate for the shipping. In any case it is a great chip.

I did, but they counteroffered wth $20, which was the same as the buy it now price.

For $15 shipping, I'm expecting it to arrive yesterday, wrapped in gold leaf.

I would've counter-offered with lower than my original offer -- hahaha. If they refused you could always just use the Buy it Now anyway.

gdjacobs wrote:

C3 CPUs are still cheap on ebay.

Even Ezra-Ts > 800mhz? I had a look for similar recently and couldn't find any worldwide.

To my knowledge, the only Ezra-T is the 1.0ghz CPU while 933mhz or less is just an Ezra.

infiniteclouds wrote:

To my knowledge, the only Ezra-T is the 1.0ghz CPU while 933mhz or less is just an Ezra.

EZRA has 100 MHz bus at speeds of 800, 850, 900 MHz or 133 MHz at 800 or 866 (and possibly 933) MHz. CPUID is in the range 0678h - 067Fh
EZRA-T has 133 MHz bus at 800, 866, 933 or 1000 MHz. CPUID is in the range 0680h - 0687h

Why is everyone so interested in getting the maximum speed out of an Ezra-T?

Is it so that you can have just one machine for newer stuff too?

I'm only really doing this project to get the older machine equivalents such as 386 and 486.

I have a Pentium Pro, PII, PIII and P4 for all the rest, though I can certainly understand wanting to have fewer boxes.

If you got the fastest Ezra-T, what Intel processor would that be equivalent to?

jamesbeat wrote:

Why is everyone so interested in getting the maximum speed out of an Ezra-T? […]
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Why is everyone so interested in getting the maximum speed out of an Ezra-T?

Is it so that you can have just one machine for newer stuff too?

I'm only really doing this project to get the older machine equivalents such as 386 and 486.

I have a Pentium Pro, PII, PIII and P4 for all the rest, though I can certainly understand wanting to have fewer boxes.

If you got the fastest Ezra-T, what Intel processor would that be equivalent to?

You answered your own question with the pretty obvious answer. Why wouldn't you want a system that can span as many years as possible?

In answer to your last question, an 866 Ezra sits around between a 200-266mhz K6-3 for general benchmarks (e.g. FPS). For artificial benchmarks that hit the FPU exclusively, I have seen a fast Ezra struggle to compete with a Pentium Pro 150.

Yes I suppose I did 🤣.

I guess you could have one of these C3 boxes and maybe a PIII and have pretty much all the bases covered.

I've probably got too many machines really, but I got really lucky - the only ones I have paid for are this C3 build and a Pentium I build that I'm gradually acquiring parts for.

The rest of them were rescued from the recycler when my job was having a clearout.

I also have another complete PIII, and motherboards/cpus for a Mendecino Celeron, a Slot 1 PIII and another P4.

I'm gonna need a bigger desk...

The top-end isn't just about max speed. You'll get a faster 'slow' speed when clocked at 1000mhz with Branch Prediction or Cache disabled than you will at 700 or 800mhz... so you can look at it as giving you faster 486 or slower Pentium speeds as well. Although like I said that chip you bought can be bumped up to 1000mhz without issue and scales really well.

squiggly wrote:

In answer to your last question, an 866 Ezra sits around between a 200-266mhz K6-3 for general benchmarks (e.g. FPS).

I'm not sure if this entirely accurate? I didn't do Quake on my 866 chip but on my Ezra-T @ 1200 mhz I get better FPS in Quake than I do on my K6-III+ @ 550mhz... about 89 FPS on the K6-III+ as opposed to 120FPS on the Ezra-T.

My 866 (stock) benchmarks were

380.0 3DBench || 97.2 PCPBench || 455.63 SpeedSYS || 113.17 FPS in Doom

infiniteclouds wrote:

I'm not sure if this entirely accurate? I didn't do Quake on my 866 chip but on my Ezra-T @ 1200 mhz I get better FPS in Quake than I do on my K6-III+ @ 550mhz... about 89 FPS on the K6-III+ as opposed to 120FPS on the Ezra-T.

My 866 (stock) benchmarks were

380.0 3DBench || 97.2 PCPBench || 455.63 SpeedSYS || 113.17 FPS in Doom

If a game is not too FPS heavy like Quake, I imagine the Ezra will do quite well. Across the board, benchmark result averages are quite ordinary though. I can't claim to have performed comprehensive benchmarks myself however.

squiggly wrote:

gdjacobs wrote:

C3 CPUs are still cheap on ebay.

Even Ezra-Ts > 800mhz? I had a look for similar recently and couldn't find any worldwide.

Been looking for an Ezra or Ezra-T > 800 MHz for probably a year by now, never even seen one for sale. No idea why. Plenty of the lower clocked models though.

My C3 Ezra is an 866 but it clocks up to 1000 mhz without issues. A slower stock clock isn't a problem as long as the core (logically and physically) supports the multipliers you want.

squiggly wrote:

infiniteclouds wrote:

I'm not sure if this entirely accurate? I didn't do Quake on my 866 chip but on my Ezra-T @ 1200 mhz I get better FPS in Quake than I do on my K6-III+ @ 550mhz... about 89 FPS on the K6-III+ as opposed to 120FPS on the Ezra-T.

My 866 (stock) benchmarks were

380.0 3DBench || 97.2 PCPBench || 455.63 SpeedSYS || 113.17 FPS in Doom

If a game is not too FPS heavy like Quake, I imagine the Ezra will do quite well. Across the board, benchmark result averages are quite ordinary though. I can't claim to have performed comprehensive benchmarks myself however.

This is good news.

As I said above, I have a PII, PIII, P4 and I have an original Pentium build underway, but it's a pain to keep a load of boxes ready to use at a moment's notice, so the more versatile my 'time machine' is, the better.

I also have a KVM switch though, so I suppose it wouldn't be too difficult to have them all set up if I really wanted to.