VOGONS


First post, by NScaleTransitModels

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Hello,

I just picked up a complete and functional 486 box. It was listed as having VLB slots, so I grabbed it to maybe do a VLB build. I was shocked when I received it today and opened it up. It came with a GA-486SA motherboard, which looks to have both EISA and VLB slots. It is almost impossible to believe, as I've never seen a EISA+VLB mobo in the wild, let alone imagine receiving one in a mystery box.

But are these really VLB slots? I recalled reading that the FX-3000 386/486 motherboards (I have a few) had proprietary "local bus" slots that would fit normal VLB cards, but fry them on the spot. And I know there were other 1992-ish proprietary local bus slots, some of which might look like VLB. What also raises suspicion on the GA-486SA is that the manual says it has "32-bit local bus" w/o mention of VESA, and FX-3000's manual said something similar.

I don't have a means to test: the PC came with a garbage ISA Trident 8900C (just sold one of the damn things 😤) and my only VLB card is a MACH32... far too valuable to risk. Has anyone owned the same motherboard to confirm it has VLB slots? Or can suggest cheap "guinea pig" VLB cards?

Also interesting to note: the GA-486SA supports 128mb of 30-pin SIMMs, and mine is still going on the original Dallas DS1387.

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Builds:

  • ECS FX-3000; 386DX-40@50; ET4000AX, ISA 1mb
  • Acer VI9; 486DLC-40; Mach32, VLB 2mb
  • Chicony CH-471A; CX486s-40; Mach32, VLB 2mb
  • Gateway 2000 P5-60; Pentium-60@66; S3 928, PCI 3mb
  • DTK PKM-0033S; AM5x86-133@160

Reply 1 of 31, by TheMobRules

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There doesn't seem to be a lot of info about that board online. Annoyingly, the TH99 page lists them as "32-bit local bus cards (2)" without providing any further details.

However, this blog post from 2009 mentions that board and claims to be using a VLB video card and I/O controller... not sure if that's enough evidence for you as the cards are not entirely visible from the pictures, so it's difficult to tell whether they're actually VLB or some other special local bus.

Reply 2 of 31, by PC Hoarder Patrol

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The Giga-Byte archive from 1977 mentions the GA-486SA as an SiS EISA rather than Opti local bus board...

"SIS.ZIP ECU for GA-486SA/TA EISA configuration utility for 486SA/TA "

This seems to be that EISA config utility (ECU) for the same

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Not sure EISA + VLB is all that rare - I have an ECS board (SL-486VE) which seems to be based on the same SiS chipset as yours, and still with its original working Dallas as well 😀

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Reply 3 of 31, by mkarcher

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The EISA slots should be real: The 85c406 (instead of a standard ISA 206) and the 85c411 are part of an SiS EISA chipset.

There is no technical reason to not build EISA/VL combo slots, but you are right that EISA/VL combo slots are rare.

I've also seen ALi chipset based 486 boards that support 128MB with 30-pin SIMMs, but I didn't yet enter the game of acquiring the required 16MB 30-pin SIMMs.

If you have a continuity tester, you might want to test address/data pins from the suspected VL slot connectors to the corresponding processor pins. Likely there are no buffer chips between the local bus slot and the processor on this board. If data and address lines match up, the slots are likely VL slots.

VL slot pinout: https://old.pinouts.ru/Slots/VLB_pinout.shtml
486 pinout: http://ps-2.kev009.com/eprmhtml/eprmx/h12203.htm (quite good site, including all the pinout variants, but they have A13 and A16 swapped)

Reply 4 of 31, by dionb

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Rule of thumb: a board with EISA-like slots with 4 or more of those slots is almost certain to be EISA, as truly local bus (OPTi etc) never supported more than three slots.

Three EISA-like slots is grey area, as there was an EISA-light controller that only did 3 EISA slots, and 3 OPTi local bus slots is theoretically possible, but unlikely.

Two EISA-like slots is most likely OPTi local bus.

A single EISA-like slot is either OPTi or a PISA slot for a riser. The latter would be on a board with PCI slots too.

Tbh, I'd be more concerned about the apparent VLB slots here than the EISA: VLB+EISA was rare, and one of the vendors doing it was ECS - but ECS had its own proprietary local bus, using the same physical form factor as VLB, just with different pinout (including power/ground pins!). However this is a Gigabyte board and never heard of them using ECS local bus instead of VESA.

I would take anything on that TH99 page with a very big pinch of salt given absence of EISA info and the listing of OPTi chipset where it's clearly SiS...

Reply 5 of 31, by Disruptor

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VLB / EISA was a good combo in those days since good EISA graphics cards were rare at this time.
VLB was a cheap addition to a chipset layout and VLB graphics cards were also cheap but faster than the EISA ones.

So the only thing that should prevent you from testing your VLB graphics card is the external clock speed.
Which processor do you use and how fast is it clocked?

However, you need to run an ECU (EISA configuration utility) tool to get rid of EISA error messages, if you have - to configure your board.

I'm a bit jealous now 😉

Reply 6 of 31, by NScaleTransitModels

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TheMobRules wrote on 2021-08-10, 06:11:

There doesn't seem to be a lot of info about that board online. Annoyingly, the TH99 page lists them as "32-bit local bus cards (2)" without providing any further details.

However, this blog post from 2009 mentions that board and claims to be using a VLB video card and I/O controller... not sure if that's enough evidence for you as the cards are not entirely visible from the pictures, so it's difficult to tell whether they're actually VLB or some other special local bus.

Right. I went through that blog post, but it's not clear if he got the VLB WD card to work. He's using an ISA ET4000AX video card in his setup. Also the I/O controller may have come w/ the motherboard, if using a proprietary bus.

PC Hoarder Patrol wrote on 2021-08-10, 06:30:
The Giga-Byte archive from 1977 mentions the GA-486SA as an SiS EISA rather than Opti local bus board... […]
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The Giga-Byte archive from 1977 mentions the GA-486SA as an SiS EISA rather than Opti local bus board...

"SIS.ZIP ECU for GA-486SA/TA EISA configuration utility for 486SA/TA "

This seems to be that EISA config utility (ECU) for the same

motherboard_driver_ecu_other_sis.zip

Not sure EISA + VLB is all that rare - I have an ECS board (SL-486VE) which seems to be based on the same SiS chipset as yours, and still with its original working Dallas as well 😀

ECS SL-486VE.JPG

Sick! I'd love to try out that utility, but don't have any EISA cards atm. Tho I'm sure another Vogoner has.
Epic find! Have you tried the VLB slots yet? Another member mentioned that some ECS boards had VLB-lookalike slots: same physical connector, but not pin-compatible.
Yours also supports 128mb. Must've been a very high-end SIS chipset.

mkarcher wrote on 2021-08-10, 07:23:

I've also seen ALi chipset based 486 boards that support 128MB with 30-pin SIMMs, but I didn't yet enter the game of acquiring the required 16MB 30-pin SIMMs.

If you have a continuity tester, you might want to test address/data pins from the suspected VL slot connectors to the corresponding processor pins. Likely there are no buffer chips between the local bus slot and the processor on this board. If data and address lines match up, the slots are likely VL slots.

For the record, I got 16mb 30-pin SIMMs to work on an OPTI-based 386 board (64mb total). Probably not allowed to post Ebay link, but they're the modules w/ 2 rows of chips: 5 on the top and 4 on the bottom, with parity.
Will consider getting a continuity tester, vs. possibly getting a junk Trident VLB card to test.

dionb wrote on 2021-08-10, 10:36:

Rule of thumb: a board with EISA-like slots with 4 or more of those slots is almost certain to be EISA, as truly local bus (OPTi etc) never supported more than three slots.

Tbh, I'd be more concerned about the apparent VLB slots here than the EISA: VLB+EISA was rare, and one of the vendors doing it was ECS - but ECS had its own proprietary local bus, using the same physical form factor as VLB, just with different pinout (including power/ground pins!). However this is a Gigabyte board and never heard of them using ECS local bus instead of VESA.

I would take anything on that TH99 page with a very big pinch of salt given absence of EISA info and the listing of OPTi chipset where it's clearly SiS...

Great to know! Looks like PC Hoarder Patrol and I have "EISA winners"... not to be confused w/ ELSA Winners 🤣
Exactly. I'm concerned that my board has those ECS or similar "fake VLB" slots that'll take a card, only to fry it on the spot. That was the case w/ the FX-3000's, which another thread mentioned had the ECS slots. Not likely on a Gigabyte board, but my VLB Mach32 is still too much to risk.
Will probably just test w/ a cheap Trident 9200. Had one at some point and it was no better than a good ISA card 🤣

Disruptor wrote on 2021-08-10, 12:10:
So the only thing that should prevent you from testing your VLB graphics card is the external clock speed. Which processor do yo […]
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So the only thing that should prevent you from testing your VLB graphics card is the external clock speed.
Which processor do you use and how fast is it clocked?

However, you need to run an ECU (EISA configuration utility) tool to get rid of EISA error messages, if you have - to configure your board.

I'm a bit jealous now 😉

It's currently running a 486SX-25 but I'd really like to build a DX2-80 out of it. If the board (or rather, its VLB implementation) won't take 40mhz clock, I'll probably just swap it w/ my PCChips M912 since that + Mach32 works at 40mhz.
So maybe, just maybe, another EISA + VLB mobo will pop up on Ebay😝
Does anyone know if early VLB boards can work at 40mhz bus speeds? Whether this one actually has VLB, it doesn't have anything like "VESA wait state" jumpers. Also, there's no clockgen chip; I'd have to buy a crystal to run at 40.

Builds:

  • ECS FX-3000; 386DX-40@50; ET4000AX, ISA 1mb
  • Acer VI9; 486DLC-40; Mach32, VLB 2mb
  • Chicony CH-471A; CX486s-40; Mach32, VLB 2mb
  • Gateway 2000 P5-60; Pentium-60@66; S3 928, PCI 3mb
  • DTK PKM-0033S; AM5x86-133@160

Reply 7 of 31, by Disruptor

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NScaleTransitModels wrote on 2021-08-10, 19:40:

It's currently running a 486SX-25 but I'd really like to build a DX2-80 out of it. If the board (or rather, its VLB implementation) won't take 40mhz clock, I'll probably just swap it w/ my PCChips M912 since that + Mach32 works at 40mhz.
So maybe, just maybe, another EISA + VLB mobo will pop up on Ebay😝
Does anyone know if early VLB boards can work at 40mhz bus speeds? Whether this one actually has VLB, it doesn't have anything like "VESA wait state" jumpers. Also, there's no clockgen chip; I'd have to buy a crystal to run at 40.

It may work with 40 MHz - or not.
I have an ATI VLB card that works well at 33 MHz and refuses at 40 MHz or even at 36 MHz - which is clearly in spec.
I have another VL board where 3 VL cards work well at 40 MHz - which is absolutely out of spec.

And I have an EISA board where I have to add waitstates in BIOS before changing the Quartz from 33 MHz to 50 MHz.
When you face problems, set your board to maximum waitstates before increasing clock frequency.

Reply 8 of 31, by PC Hoarder Patrol

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The SiS chipset on your board looks similar to mine, although I'm sure I did once read that SiS could also support Opti local bus!

I'm hoping to make a build with this board soon, although suitable period cases are limited atm. I have both EISA & VLB video cards tested working with the board, but will likely stick to VLB to free up the other busmaster EISA slots for other cards.

Here's the intro pages from my boards manual for info

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Reply 9 of 31, by TheMobRules

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Just found this post from 2013. Apparently Gigabyte did use a proprietary 32-bit local bus on the GA-486US motherboard! But the implementation is described as being "two 16 bit ISA slots in a row", which is clearly not your case:

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So I'd say there's a high chance that the slots on your board are VLB, unless Gigabyte created two different slot types for its proprietary bus around the same time, which doesn't sound very likely.

EDIT: stole the pictures from that thread

Reply 10 of 31, by mkarcher

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PC Hoarder Patrol wrote on 2021-08-10, 20:09:

The SiS chipset on your board looks similar to mine, although I'm sure I did once read that SiS could also support Opti local bus!

As long as you don't need bus mastering, you can "bodge on" the local bus slots without specific chipset support. For example, I have an Opti Local Bus board with a classic 486 ISA chipset. The chipset already supports a Weitek 4167 coprocessor, which essentially is nothing different from a local bus device. Now add some OR gates that combine the "This is a Weitek Cycle" signal from the coprocessor socket with the "this is my local bus cycle" signal from the Opti / Gigabyte / VESA local bus slot, and your local bus board is done. So any chipset from any manufacturer can easily be used on boards that support any kind of non-master-capable local bus slots.

Proper VL support includes busmastering which needs an arbitrator that distributes bus access between ISA DMA, the processor, and the master-capable VL slots. Such arbitration is also possible as add-on for a chipset (and is the reason why some boards had "VL PALs" to be equipped for full VL support), but most master capable VL boards have more recent chipsets with arbitration built into the chipset.

Reply 11 of 31, by BitWrangler

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I saw inside a 486 system that was pre VLB, had been a CAD workstation with a DX50, and that had weird extended EISA slots that took proprietary RAM expansion boards, massive things with 8MB on each.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 13 of 31, by maxtherabbit

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Should be super easy to see if the VLB power and ground pins are at least in the right place by checking continuity to the AT-power connector with no power supply connected. Once you've crossed that hurdle should be perfectly safe to stick a VLB card in and see if it works.

Cool board!!

Reply 14 of 31, by Anonymous Coward

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BitWrangler wrote on 2021-08-10, 21:54:

I saw inside a 486 system that was pre VLB, had been a CAD workstation with a DX50, and that had weird extended EISA slots that took proprietary RAM expansion boards, massive things with 8MB on each.

Was it an AST system? It almost sounds like the CUPID bus.

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V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 15 of 31, by NScaleTransitModels

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Disruptor wrote on 2021-08-10, 19:49:
It may work with 40 MHz - or not. I have an ATI VLB card that works well at 33 MHz and refuses at 40 MHz or even at 36 MHz - whi […]
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It may work with 40 MHz - or not.
I have an ATI VLB card that works well at 33 MHz and refuses at 40 MHz or even at 36 MHz - which is clearly in spec.
I have another VL board where 3 VL cards work well at 40 MHz - which is absolutely out of spec.

And I have an EISA board where I have to add waitstates in BIOS before changing the Quartz from 33 MHz to 50 MHz.
When you face problems, set your board to maximum waitstates before increasing clock frequency.

Unlikely to work at 40... IME VLB always needs a waitstate at 40. Just checked mine and there are no local bus waitstates thru jumpers or BIOS.
Made a final decision to sell this one (eventually, I have too much to list but not enough time) and swap in a late VLB motherboard. I'll make sure it goes to a good home.

But before I do, I will check if the slots are actually VLB. I just placed an order for a cheapo Trident. Appreciate the tips on continuity testing but will have to save that for another day.

PC Hoarder Patrol wrote on 2021-08-10, 20:09:
The SiS chipset on your board looks similar to mine, although I'm sure I did once read that SiS could also support Opti local bu […]
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The SiS chipset on your board looks similar to mine, although I'm sure I did once read that SiS could also support Opti local bus!

I'm hoping to make a build with this board soon, although suitable period cases are limited atm. I have both EISA & VLB video cards tested working with the board, but will likely stick to VLB to free up the other busmaster EISA slots for other cards.

Here's the intro pages from my boards manual for info

ECS SL-486VE Intro.jpg

Sweet! It would be great to see your build, though I feel your pain as the supply of AT cases has really dried up over the past year. Maybe COVID causing a demand surge for "stay at home" hobbies?

Also noticed that that manual page mentions "master" and "slave" VLB slots... from what I'm reading, that has to do w/ bus mastering. I guess bus mastering on one slot at most.

mkarcher wrote on 2021-08-10, 21:04:

As long as you don't need bus mastering, you can "bodge on" the local bus slots without specific chipset support. For example, I have an Opti Local Bus board with a classic 486 ISA chipset. The chipset already supports a Weitek 4167 coprocessor, which essentially is nothing different from a local bus device. Now add some OR gates that combine the "This is a Weitek Cycle" signal from the coprocessor socket with the "this is my local bus cycle" signal from the Opti / Gigabyte / VESA local bus slot, and your local bus board is done. So any chipset from any manufacturer can easily be used on boards that support any kind of non-master-capable local bus slots.

Proper VL support includes busmastering which needs an arbitrator that distributes bus access between ISA DMA, the processor, and the master-capable VL slots. Such arbitration is also possible as add-on for a chipset (and is the reason why some boards had "VL PALs" to be equipped for full VL support), but most master capable VL boards have more recent chipsets with arbitration built into the chipset.

Interesting... would bus mastering affect speed for VGA VLB cards? Video bandwidth will be pretty important as I'm trying to test video playback on a 486 VLB build.
I remember my cruddy PCChips M601 wouldn't play video w/ a DX2-66, and was horribly unstable at that too. Wonder if it lacked VLB bus mastering or if I'd missed some timing settings. Meanwhile the much newer M912 will do it w/ the same video card, even w/ a DX-40.

Builds:

  • ECS FX-3000; 386DX-40@50; ET4000AX, ISA 1mb
  • Acer VI9; 486DLC-40; Mach32, VLB 2mb
  • Chicony CH-471A; CX486s-40; Mach32, VLB 2mb
  • Gateway 2000 P5-60; Pentium-60@66; S3 928, PCI 3mb
  • DTK PKM-0033S; AM5x86-133@160

Reply 16 of 31, by TheMobRules

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NScaleTransitModels wrote on 2021-08-12, 18:57:

Interesting... would bus mastering affect speed for VGA VLB cards? Video bandwidth will be pretty important as I'm trying to test video playback on a 486 VLB build.
I remember my cruddy PCChips M601 wouldn't play video w/ a DX2-66, and was horribly unstable at that too. Wonder if it lacked VLB bus mastering or if I'd missed some timing settings. Meanwhile the much newer M912 will do it w/ the same video card, even w/ a DX-40.

A while back someone on this forum told me that VLB graphics cards do not use bus mastering. VLB bus mastering only seems to be important for SCSI controllers.

If you are interested in video playback on a VLB build maybe a card based on the S3 Vision868, 968 or Trio64V+ would be useful as the difference vs. 864, 964 and Trio64 chipsets is that the Vision x68 and Trio64V+ include video acceleration features. But VLB cards with those chipsets are usually expensive, and I'm not sure if it really helps that much for video playback.

Reply 17 of 31, by PC-Engineer

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dionb wrote on 2021-08-10, 10:36:

Tbh, I'd be more concerned about the apparent VLB slots here than the EISA: VLB+EISA was rare, and one of the vendors doing it was ECS - but ECS had its own proprietary local bus, using the same physical form factor as VLB, just with different pinout (including power/ground pins!). However this is a Gigabyte board and never heard of them using ECS local bus instead of VESA.

I have this ECS Board (SL486VE) and the VLB-Slots are full VESA comaptible, tested with several VLB cards. Currently its running with a Mach32VL. Also the Socket 3 supports full compatibility with the P24T (tested too).

As the SIS 406/411 Chipset is a EISA/VL combo chipset, the Gigabyte 486 SA board has fully compatible VLB and EISA Slots! I am looking at a test of this board from 05/1993 (c’t magazine) right now with confirmation of its compatibility. They also tested a Mach32VL

Last edited by PC-Engineer on 2021-08-12, 21:39. Edited 1 time in total.

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Reply 18 of 31, by Bancho

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I have a EISA/VL system built, although its not really fully finished yet. I need to find the EISA Configuration utility. I have the original disk but unfortunately its bad 🙁 I need to Change both Dallas's on it too as they are dead.

My board is a Asus VL/EISA-486SV1 which I currently have a DX2 66mhz and 16mb of ram in, CL VLB VGA Card and Tekram EISA HDD/FDD controller with 4mb cache

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Reply 19 of 31, by BitWrangler

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Anonymous Coward wrote on 2021-08-11, 00:51:
BitWrangler wrote on 2021-08-10, 21:54:

I saw inside a 486 system that was pre VLB, had been a CAD workstation with a DX50, and that had weird extended EISA slots that took proprietary RAM expansion boards, massive things with 8MB on each.

Was it an AST system? It almost sounds like the CUPID bus.

I either didn't know or can't remember. I am leaning to thinking it wasn't. I think I looked into the system manufacturer at the time and while they were minorly famous in CAD and engineering for their high spec systems the rest of the computing world ignored them. It was an old-ish system by the time I saw it in '96 sometime, but the spec of the parts kept it almost level with the generic 486dx66 multimedia boxes sold as entry level still then. Not sure exact date 91 or 92.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.