VOGONS


First post, by FGB

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si5pi_aio_rev_1.1_socket_4_motherboard-600x396.jpg

I recently got my hands on a really nice Socket 4 motherboard from 1994, by far the nicest which has come along my way. I totally fell in love with it. Let me tell you why...

It's the Elitegroup SI5PI AIO with the triple-chip SiS chipset 501 502 and 503. In contrast to the vast majority of other Socket 4 boards with their quite rudimentary set of BIOS options you can tweak nearly everything (including cache timings, dram timings, clock dividers) here. The Award BIOS is also not affected by the infamous variation of the Y2K bug which causes the year to either fall back to 1912 or go to 2094 in the future. The date is stored on a changeable RTC Module from Benchmarq.

The mobo comes with the buggy CMD 540B PCI-EIDE controller, but we all know there are effective workarounds, you can also disable the CMD 32-bit transfer mode complete in the BIOS, if you want.

The PCI-Performance is also very good, taking into account that the board is such an early make of a PCI-Bus based board. Talking in numbers a S3 Virge (325) with 4MB has a Vesa Memory bandwidth of 22,5MB/s, a TsengLabs ET6000 has a bandwidth of 48MB/s. These values are very very fast and represent the hardwarelimit of the cards. So the PCI-Bus is no bottleneck here.

sis503_chipset_sis501_sis502_on_si5pi_aio_motherboard.jpg

One of the most interesting parts of the motherboard is the L2 cache subsystem. In opposite to almost all the other Socket 4 boards the ECS has no soldered sram-modules but a field of sockets that can handle 4, 8 or even 16 modules for up to 1MB L2 cache. That is quite unique and makes the board capable of cache bank interleaving which gives the subsystem a very nice performance boost. And if you put 512KB cache into its place the whole maximum? amount of 128MB system memory is cached.

I ran various tests including 3DBench, PCPBench and SpeedSys and must say that the system really flies. I think the values confirm that the system is just darn fast for just 66MHz core clock:

ecs_si5pi.png

The other very very interesting part of the board is the built in MX8315PC clock generator IC that is responsible for the host clock. The board has three jumpers for the bus clock and you can programm either 60MHz or 66MHz depending on your CPU (but every 60MHz Pentium should handle the 66MHz). But there are other possible (undocumented) settings. You can also jumper the board to 20mhz, 33mhz, 40mhz, 50mhz! These settings work rock stable and in combination with cache/on/off settings in the BIOS you are able to go down to very low speeds, to the sweetspot of speed sensitive games like e.g. Wing Commander.

I think this board is the ultimate 486 replacement. Put it together with a nice highly compatible ViRGE or an ultra fast (under DOS 😉 ) Riva128 or ET6000 card and a Gravis Ultrasound and a nice and clear General Midi / SoundBlaster / Roland solution and you have a stunning good rig for many years of computer gaming history:

On the one hand it has the performance of a fast DX4 or even 5x86 that allows one to play all the VGA games that require much cpu speed to run smoothly. Together with the strong FPU and the potent PCI-Subsystem you may also be able to run the very early (!) SVGA or more FPU demanding games. On the other hand you can slow this machine down to the stoneage. With 20MHz and no cache activated it is as slow as a 286. And you can hardware adjust other speeds and combine them with cache options so all the old games run without a slowdown program which may refuse to work with game A or B.

I hope you like this board as much as I do. Please tell me what you think about this solution instead of the more common high end 486 system?

German readers may be interested to read something in German. Please visit my retro-computing collection / blog:
http://www.amoretro.de/2012/03/si5pi-aio-rev- … otherboard.html

Fabian

www.AmoRetro.de Visit my huge hardware gallery with many historic items from 16MHz 286 to 1000MHz Slot A. Includes more than 80 soundcards and a growing Wavetable Recording section with more than 300 recordings.

Reply 1 of 17, by luckybob

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god thats sexy...

i've loved the odd sockets that came out. (4 & 😎. Plus all that pretty gold just gleams. ^.^

It is a mistake to think you can solve any major problems just with potatoes.

Reply 2 of 17, by DonutKing

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If I'm reading right, your processor is SX835 S-Spec, which has the FDIV bug.... making it a bit of a collectors item 😀

I have a 60MHz Socket 4 system here as well, although in my testing with Doom and other DOS games, it seemed around equal to a 486DX4-100. It's real advantage would be 3D games like Quake.

If you are squeamish, don't prod the beach rubble.

Reply 3 of 17, by gerwin

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Interesting review you got there, and the pictures are excellent.
"20mhz, 33mhz, 40mhz, 50mhz" That is pretty amazing. So that is socket 4.... I have no hardware from before super socket 7 myself.

Stumbled upon your website a few times before, you did a good job with that. Being from Holland I can read German to some degree. Thanks for sharing all that retro hardware.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 5 of 17, by feipoa

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A very fine board indeed! I don't recall ever seeing a motherboard with 18 DIP-32 cache sockets before. Any chance it can handle 2 MB of L2 cache?

The socket 4 Pentium 60/66 is the ony Pentium1 I won't be able to include on the Ultimate 686 Benchmark Comparison. How would you like to run the ensuite of benchmarks and add them to the test matrix for 60 and 66 Mhz operation? Do you have a chip without the FDIV bug?

I have attached an example of the test matrix, including which programs to run, and how far along this project is to date. EDIT: test matrix has been removed.

Last edited by feipoa on 2012-07-26, 04:12. Edited 1 time in total.

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 6 of 17, by FGB

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@gerwin: Thanks for your comment and for your compliment regarding my website. please don't take the different bus-speeds as representatitve for other socket 4 boards. I think this is just a unique (still unwanted by the manufacturer) feature of the ECS board.

@dirkmirk: Yes, you are right, there are such overdrive CPU's for socket 4, but they are of course hard to find. There are even socket 5 adaptors that accept IDT winchips with MMX and 3Dnow! on this board - of course they are rare, too.

@feipoa: Yes, the SiS chipset can handle 2MB of Cache. It's just not printed on the board as an official option. I really appreciate your comprehensive work you did with your 486-benchmark project and yes, I would like to contribute my data to the "Ultimate 686 Benchmark Comparison" although I think the word "686" is really misleading if you take a closer look into the different cpu technologies you want to compare. IMO it would be better to compare the CPUs by using the same socket or at least a similar socket (e.g. socket 4 / 5 / 7 CPU's from Pentium 60MHz to K6-3+ 600MHz in one and "real 686" CPUs from Pentium Pro and Slot 1 / Slot A and upwards in another comparison). I also have a chip without the FDIV bug, would be no problem to use this one. I also have a Slot A Athlon Classic 1000MHz V5 / V2 SLI retro rig that could be compared.

Cheers
Fab

www.AmoRetro.de Visit my huge hardware gallery with many historic items from 16MHz 286 to 1000MHz Slot A. Includes more than 80 soundcards and a growing Wavetable Recording section with more than 300 recordings.

Reply 7 of 17, by feipoa

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I've been trying to figure out a better name for the comparison for some time. If you have any name suggestions, please let me know. I am looking for a single world substitute for "686" and don't want some long drawn out and overly descriptive title. I don't have any Pentium Pros or Slot A's and am no longer actively sourcing components. I originally did not have the slot 1's on the comparison, but people have been requesting to have them added, so I decided to draw the line at 600 MHz.

I would like to see if your socket 4 motherboard will actually work with 2 MB of cache. Can you check for this using CTCM?

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 8 of 17, by FGB

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Well I do not have so much cache. And even the 512KB configuration hasn't proven to be stable. The board crashes after ~2hrs. I think it's because the manual says that 12ns Tag-Rams are required for the "fastest" mode. I got only 15ns modules installed.

Do you know where to get them?

www.AmoRetro.de Visit my huge hardware gallery with many historic items from 16MHz 286 to 1000MHz Slot A. Includes more than 80 soundcards and a growing Wavetable Recording section with more than 300 recordings.

Reply 9 of 17, by feipoa

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I was able to source 10 ns cache for '256', '512', and '1024' chips. They will come from old stock warehouses in China. I recommend reading through this thread,
Re: Super Fast 486 Cache - 10 ns
and also the sub-link contained therein.

I had extended my IC sourcing service to all other Vogons members at the time of ordering, but there didn't seem much demand for it. Only two other Vogons members ended up with the 10 ns cache. However, I've gotten quite a bit of interest from others since then. Unfortunately, it is too much hassle for me to do again, but if anyone else wants to take on this burden, I'll take more of the '1024' and '256' pieces.

If you don't mind paying a small fortune, you can still find 12 ns '256' cache on eBay, however I'd imagine you'd want a 10 or 12 ns '1024' piece.

Did you check your socket 4 motherboard for stability on the 'faster' setting and 512 KB cache?

On another topic, how is it that you take such sexy hardware photos? Do you have one of those white box jeweller type setups?

Ultimate 486 Benchmark | Ultimate 686 Benchmark | Cyrix 5x86 Enhancements | 486 Overkill Graphics | Worlds Fastest 486

Reply 11 of 17, by Tetrium

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ncmark wrote:

I didn't realize socket 4 was pentium 😦 😦

I'm assuming it's NOT possible to run a 486 on it....

Nope, the only CPU's for Socket 4 are the very original Pentium (the 60 and 66Mhz variants only) and the Pentium Overdrive 120/133Mhz (which is impossible to find).

Whats missing in your collections?
My retro rigs (old topic)
Interesting Vogons threads (links to Vogonswiki)
Report spammers here!

Reply 12 of 17, by kool kitty89

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Tetrium wrote:
ncmark wrote:

I didn't realize socket 4 was pentium 😦 😦

I'm assuming it's NOT possible to run a 486 on it....

Nope, the only CPU's for Socket 4 are the very original Pentium (the 60 and 66Mhz variants only) and the Pentium Overdrive 120/133Mhz (which is impossible to find).

Were there ever any socket adapters?

Reply 13 of 17, by Anonymous Coward

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Yes. There is one used in Socket 4 Dell systems that converted Socket 4 to Socket 5. That would take you up to a P166. There are also a few adapters from powerleap. One of them supposedly will let you upgrade to K6-2 400MHz. I've been trying to get my hands on one of those for years.

I had a P120/133 overdrive but sold it several years back after my Socket4 VLB board kicked the bucket.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 14 of 17, by FGB

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Anonymous Coward wrote:

Yes. There is one used in Socket 4 Dell systems that converted Socket 4 to Socket 5. That would take you up to a P166. There are also a few adapters from powerleap. One of them supposedly will let you upgrade to K6-2 400MHz. I've been trying to get my hands on one of those for years.

I had a P120/133 overdrive but sold it several years back after my Socket4 VLB board kicked the bucket.

was it one of the very slow "OPTi Premium" driven boards?

www.AmoRetro.de Visit my huge hardware gallery with many historic items from 16MHz 286 to 1000MHz Slot A. Includes more than 80 soundcards and a growing Wavetable Recording section with more than 300 recordings.

Reply 15 of 17, by s.mouse

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Hey FGB enjoyed the read thanks

Would you or anyone else have a copy of the AWARD bios? I would like to try it out as my board has a phoenix bios. I can only seem to find the phoenix rom online

Reply 16 of 17, by Moogle!

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I have one coming. If it has the Award as the sticker suggests, I'll dump it for you. Be careful though and make sure you backup the Phoenix. Some BIOSes are written for one board configuration, and some BIOSes may be written for another. Usually the I/O chip may be different, or possibly the keyboard/mouse controller may be different and will not work if it is the wrong image. I had this happen to me with a Tyan HX board. I might like to take a look at that Phoenix myself, because I like subjecting myself to pain sometimes.