Disaster struck while working on this odd-ball 386SX VLB motherboard

VLB or VESA Local Bus was introduced with the 486 to break the bottleneck that the ISA bus had become. This is a 386SX motherboard with VLB slots. How is this even possible?
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[@adriansdigitalbasement2]

A couple notes: I tested the two sticks of RAM and they were 4mb each. I also tested the math co-processor and that works just fine in another 386SX board.

[@Fergo101]

I’m guessing that’s a spoiler

[@only257]

@@Fergo101 agreed 😊

[@timballam3675]

Have you found a combined ISA/VLB/EISA board yet? The Pentium PCI/VLB boards were awful, normally only used as an upgrade path so people could use their VLB graphics card!

[@freeculture]

@@timballam3675 I have never seen both in the same motherboard. Usually EISA had all slots EISA, white for some reason.

[@ytmadpoo]

We learn from failures, so it's not a total loss. You take this knowledge and roll it forward to the next time.

[@tw11tube]

It's a common misconception that the 386SX is basically a 386 "with th 286 bus interface". While it is completely true that the number of address and data lines on the 386SX is just like on the 286, the *protocol* of the 386SX is very much like that of the 386DX, but it differs from the 286 bus protocol. For example, the 286 bus protocol generally allows the processor to output the address of the next bus cycle while the previous cycle is still being finished, and actually the address pins are *always* valid half a processor clock (one period of the CLK2 signal) before the bus cycle is started. On the other hand, on the 386 bus protocol, the address stays valid during one cycle unless the mainboard actively allows the processor to output the address of the subsequent cycle (using the "NAB#" signal - "next address to bus"). The 386SX uses the same timings and protocol details as the 386DX, it just has fewer data lines, it misses the top 8 address lines and has the extra line A1. Also, it only has two "byte enable" signals, whereas the 386DX has four byte enable signals. Furthermore, you are in fact correct that most 386SX chipsets also support 286 processors, but the chipset needs to be configured for the bus protocol to use. Most 286 chipset vendors added support for the 386 bus protocol in their newer chipsets to increase the market for their chipsets. A passive adapter from 286 to 386SX on the other hand won't work. As I don't expect that board to support VLB masters, it's up to the processor to determine the width of cycles.The VESA local bus is perfectly able to handle 16 bit cycles originating from a 32-bit processor, so the VESA local bus is also able to handle 16 bit cycles originating from a 16-bit processor. On the XT-IDE card, the IDE/ATA interface *requires* 16-bit cycles to be performed on that interface, which is something 8-bit ISA is not capable of, so that card needs to assemble two 8-bit ISA cycles into one 16-bit IDE cycle. I am very confident that your board will not run any VL card that requires bus operations to be performed as 32-bit cycles. VL VGA cards generelly do not require that (unless special accelerator feature do), as well as VL IDE controllers also work perfectly (also sometimes slower) with 16 bit cycles only. There is one thing the board has to perform, though: The high two bytes of a DWORD *must* be transferred on D16-D31, so the board needs to dynamically connect either D0-D15 of the VL slot to D0-D15 of the processor, or D16-D31 of the VL slot to D0-D15 of the processor. That's exactly what the four (74)F245 chips can do. In fact, stuff like this is also performed on some video cards, like Cirrus Logic cards. The CL-GD542x series are *16-bit* local-bus capable graphics chips! The VESA local bus has a signal to tell the processor that only a 16 bit cycle has been accepted by the device and the board/processor is required to re-issue a cycle for the remaining byte(s), if any. Logic on a CL-GD542x card detects whether one of the two low bytes is active, and if yes, it performs a 16-bit cycle using D0-D15 (or an 8 bit cycle with half of the data lines), otherwise it performs a 16-bit cycle using D16-D31 (or a subset). In essence, this means the 16-bitness of your board should not degrade performance of a Cirrus Logic card. This does not apply to the CL-GD5430 or CL-GD5434, though.

[@darknase]

Well TL;DR 80386SX is a cut down version of what was to become a 80386DX, it has the same limited 16-bit Data and 24-bit Address bus, just as a 80286 but it's a real 32-bit 386 CPU just cut down IOs, not much unlike a 8086 vs. 8088 where the data bus is halved from 16-bit of the 8086 to 8-bit in the 8088. The 386 has in it's ISA significant differences to the 80286 beyond the expansion from 16 to 32 bit execution, as such it has the Real Mode (8086, 80286, 80386), Protected Mode (80286, 80386), Virtual 8086 (80386), which was at the time a major advantage levied by Windows 3.0, and OS/2 2.0. The 80386 also introduced a flat memory model versus a segmented/paged/stacked memory model of the 8086 & 80286 (and coincidentally 80186, that was never really part of the PC ecosystem)

[@Nossieuk]

People are here for your personality, expertise and your content - I don't think people are too bothered about a bad zoom on the hardware or bad cuts - loving this channel almost as much as your main one so just do what you enjoy and what's easier for you.

[@Nossieuk]

my original packard bell was a P60 (with the bug) and had VLB, there were some PCI slots but I must say I never tested the speed - that was over 20 years ago now!

[@AceStrife]

Same with LGR and his blerbs channel; just had a brief mention at the end of one of his videos and suddenly 70k subscribers after being made. Random viewers browsing youtube may not find a casually recorded/edited video appealing as their first entry, but for those who are already part of the regular viewerbase, we'll gladly watch them. And honestly, I can barely even tell the difference between the main and alt channel videos anyway! They're still that good.

[@soberlife]

Adrian could read a dictionary and I would still watch.

[@necro_ware]

Hi Adrian, sorry for making an announcement here, but I wouldn't if it wouldn't fit so good ;) Accidentally, I'm currently preparing a video about another 386-ish board, which also has VLB. That is a 386DX (unfortunately not a 386SX), but if everything is going as planned, I'll try to show some performance results as well. Btw. your board is not quite a 386SX, it is an extended version made by Cyrix/Ti. It is a reduced version of a 486, which was made to fit 386SX boards and is also known as IBM lightning.

[@adriansdigitalbasement2]

I have a couple 386/486 boards with VLB that can run either chip. Kind of interesting but just seems wild to have 32 but CPU here with a 16 bit bus connected to a 32 bit slot! I have done some testing of 33mhz 386DX VLB vs a 486DX33 VLB and they seem roughly the same speed, which makes sense since it's just 32 bit all the way.

[@barttenbrinke2155]

I had this board in my Tulip PC around 1995? The vlbs where occupied with a vga card and a scsi card that drove the harddrive. I bought the pc second hand and it was originally used as a CAD station.

[@necro_ware]

@@adriansdigitalbasement2 Well, if we are talking about throughput they are probably the same yes, however it's a little bit hard to compare a 386DX with a real 486 clock for clock. Due to the integrated L1 cache in the 486 and its pipelined design, it was by far more efficient per MHz compared to 386DX. Even the Cyrix/Ti 486SXL, which were drop in replacements for the 386DX lost against a real 486 by a huge margin. They usually had only 1kB L1 cache (vs 8kb in i486) and were based on Cyrix weaker overall design back then. As a result there are barely benchmarks available, which would give us clean view on VLB performance differences. All I can tell is, that even 386DX benefits from VLB, just as you said in the video, probably because of higher effective clock and therefore throughput. But the sweet point where VLB shows its full strength over ISA is somewhere between DX2-66 and DX2-80.

[@mmllmmll22]

@@necro_ware our german friend is goin to upload a vid! I can't wait for it now...

[@herrbonk3635]

@@adriansdigitalbasement2 Perhaps similar for VLB transfers. But if you compare the 386 and 486 on pure calculation loops, you will find that the 486 is about twice as fast as the 386 at the same clock speed.

[@andyhu9542]

5:37 Those for chips are NOT latches, but high-speed bidirectional bus drivers. The model is F245, or 74F245, the F variant of the common 74LS245. The fact that there are 4 chips seems to indicate that the VLB is indeed 32-bit. However, there are 16-bit VL cards. The most famous example is the CL-GD5428 graphics card which use a 16-bit data bus and 24-bit address bus instead of 32-bit. A standard for 16-bit local bus may exist, but just rarely used.

[@wmlindley]

Quite. "9344" is the date code (44 week of 1993)

[@hermannschaefer4777]

It is also known that those chips draw quite a lot of power and should not be switched simultaneously. Amiga used different types(!) for one 16-bit bus just to make sure that both chips don't switch at the same time. Weird stuff back then..

[@vwestlife]

My first 486 was an IBM 486SLC2-66 with VLB slots. The 16 MB RAM limit wasn't an issue back then (I only had 4 MB in it anyway), and with 16 kB of L1 cache, it was almost as fast as a 486DX2 when running small CPU-intensive tasks -- but obviously the 16-bit external data bus slowed it down a lot when I/O was involved. Supporting 32-bit VESA Local Bus cards wasn't a problem; it just had to transfer the data in two 16-bit chunks at a time. My only complaint was that the little one-inch-square CPU had a tiny fan on it that was not only loud, but also didn't fit under the drive cage of the desktop case I wanted to put it in! So I was forced to get a tower case with more room above the motherboard.

[@retrozmachine1189]

Nice. I put together a bitsa small Netware 3.12 server for someone that wanted a very low cost basic file server running Netware. It used an IBM branded (God only knows who actually made it) motherboard with one of those CPUs soldered on. It ran flawlessly for years even to the point of being forgotten about and lost in the office space it was used in but continuing to plug on regardless. Quite surprising really all things considered.

[@adriansdigitalbasement2]

So basically something very much like this! Interesting! I just don't get why they even bothered with VLB ... But I suppose it ran faster than 8mhz ISA... So there was some benefit. I know you have a lot of machines, you don't still have it anymore?

[@vwestlife]

@@adriansdigitalbasement2 No, I got rid of it a long time ago, back in the late '90s.

[@kaitlyn__L]

That must be hence the “AKA IBM 220”

[@the_kombinator]

If you don't care about the FPU, this processor was just fine. I had one up until very recently (actually, I had an Ambra and an Alaris) and it was about as good as an SX2-50.

[@roadsiderebels3039]

I like the setup. I feel like I'm sitting at the workbench with you watching you do your thing. I appreciate you making me comfortable. Disasters happen, been there done that. Good content.

[@thehighwayman78]

Exactly! Couldn't have said it better myself

[@dachannien]

A real bummer that this board got toasted by a random PSU failure. But props to you for posting this "mission failed" video anyway! Always interesting to see the artifacts you turn up.

[@1pcfred]

PSU failures are not random, they're inevitable. The only question is when will the PSU fail, not if.

[@lukehindman4498]

The new setup worked really well. It is sad to have the motherboard killed in that manner. With that kind of power failure, any number of chips could have been burned out. 😕

[@herrbonk3635]

1:20 I wouldn't call a 386SX "essentially a 286". Sure it has a similar bus and similar performance (on 16-bit code), but the instruction set was heavily updated and orthogonalized for the 386 (including the later SX). Actually more so than on any other new x86 processor. It would be more correct to say that the Pentium III was essentially a Pentium II (or Pro), for instance.

[@fromtheashesit7782]

Hi, that looks like an early "Blue Lightning" IBM 486SLC2. The rev after yours even lists its processor as a 486SLC2.

[@xerxes4863]

Thank you, Adrian. So nice to see that one isn't alone in having old stuff fail on you, damaging something you're working on. This actually makes my life more bearable. You're great! Get better soon!

[@fluffycritter]

It's a bit odd to refer to a 386SX as "basically a 286," since it still had the full 32-bit instruction set and the i386 protected mode (which was vastly different than, and superior to, the i286 protected mode). There's a *lot* of stuff that runs on the 386SX that wouldn't run on a 286, even if the overall performance isn't much higher for 16-bit applications.

[@misterkite]

Yeah, as a programmer I cringed a little every time he said it was basically a 286. You won't be able to run any software that uses PMODE/W on a 286. That's pretty much everything from the demoscene.

[@cliffshockley4406]

Just to clarify "a 386sx is basically a 286", while true it has a 16-bit external data bus, it also has an internal 24-bit address bus. Plus it includes the 386 processor extensions to the x86 instruction set.

[@AndyJRoss71]

Gotta quibble with the equating of a 386sx with a 286. It's true that they share (almost) the same bus interface and tended to go into the same sorts of AT clones. But the 386sx was internally a real 386 core, 3x as many transistors, 32 bit registers, a paging MMU, emm386 compatibility, dos4gw, the works. Hell, you could (and many people did) run Linux on the 386sx. But it's true that almost all the chips were deployed in environments where they only ran AT software.

[@adriansdigitalbasement2]

I thought I was clear I was saying it was the electrical and external interface that was the same but clearly internally it's upgraded. The 486SLC on this board even has internal L1 cache and is clock doubled internally, making it somewhat speedy, albeit extremely crippled with the limited external bus limitations.

[@foogod4237]

@@adriansdigitalbasement2 To be honest, I had somewhat the same quibble too.. The way you phrased things in several places it really did sorta seem like you were saying "the 386SX was basically just a rebranded 286", which was actually quite far from the case, both in terms of design and capabilities. I could tell what you _meant,_ but some people might get the wrong idea based on how things were said...

[@greggv8]

@@foogod4237 The craziest PC CPU ever has to be the Texas Instruments 486SX they made as a plug in replacement for PLCC 80286 chips. It was pretty popular as an upgrade for old laptops. I knew someone who put one in an old laptop with an amber plasma display and another in a PS/2 Model 60, along with every other upgrade he could possibly stuff in, and it was still super slow. He tried to give it to me, several times. ;) I don't recall if TI made it in an LCC type. 12Mhz 80286 LCC chips were common desktop CPUs. I always thought the little heatsink on the clip was ridiculous since no 286 ever got more than barely warm. I did somewhat lust after having a 16 Mhz 286 but apparently they were rare, or sellers just figured (as they always have) the absolute fastest CPU for any given PC platform should be worth almost double the CPU one step down in speed. I'd love to have my super 286 back. I had 12 megabytes of RAM in it. 512K in DIP chips on the board, the rest was on three Micron 16 bit ISA cards. Split between backfilling low RAM to 640K and 50/50 between XMS and EMS. I had a Pro Audio Spectrum 16 in it (a Reel Magic card minus the SCSI and VGA components) and a Soundblaster 2, with autoexec.bat and config.sys and Windows 3.11 (the OEM only version which still had Standard Mode) all configured so any game I had would automatically be able to use whichever was the best sound it supported. How I got the RAM cards was a friend wrote a school paper on waste in the computer industry and Micron gave him six obsolete, new in box, RAM cards. He couldn't use all of them so he gave me three.

[@andrewlittleboy8532]

Thanks Adrian for making a video even when feeling rough! 😊

[@more.power.]

Thanks Adrian another great episode. Cheers

[@Arti9m]

Thank you for sharing this. Somehow it makes me feel less sad about my own failed repairs =)

[@DiazFelix]

A 32 bit processor with external 16 bit bus using 32bits slots... a bit madness. wide>narrow>wide

[@garthhowe297]

Boy...I was working at a reseller from 1990 onwards...and I barely remember VLB. It was a very short-lived bus. A troubleshooting session with you is a great learning experience, regardless of the outcome.

[@belzebub16]

Really enjoying the added production value of your OBS setup for the 2nd channel - awesome 👍

[@sendark001]

get well soon mate!

[@semuhphor]

Hope you feel better.

[@iteachtime]

Thanks for another awesome learning experience. Did not know any of that about VESA slots. Now I finally understand what latches are too!

[@adriansdigitalbasement2]

Appreciate the super thanks! Glad you liked the video. It would have been amazing to get this working but at least it was a journey, as usual. :-)

[@wessd]

I had a 486slc ibm...it was a weird chip might have been a blue lightning but it for sure was not a 486 chip, it had both vlb video and hd cards. the video was a number 9 vlb card... it was a very nice.

[@scottharvey-davies1607]

Kudos to you for the new camera setup ;)

[@vwestlife]

As for the motherboard not working with the XT power supply -- it may require +5V on pin 2 of the P8 power connector, while XT power supplies do not have anything connected to this pin. I haven't heard of any AT motherboards actually requiring +5V on pin 2 of P8, but it's just a thought.

[@adriansdigitalbasement2]

Nice. I'll give it a try with my new bench supply. I swapped over to an older ATX PSU with AT adapter for lab work. (ATX with both -5 and -12) I fear the motherboard is gone though as at least one IC was damaged, it seems like 12v may have made its way to the 5v rail when the PSU decided it was time to die. LOL

[@solarbirdyz]

What we said at Microsoft at the time - and it was generally applicable - was "Remember: the S stands for Sux!" (Yes, that applied to Win32s as well.) But admittedly, there was one advantage to the 386sx from a development standpoint, in that you could treat it as a 386 and not have to deal with bloody segmenting. While technically it (and the 386dx) still had segments, they became settable and arbitrarily large, so you could set your segment to all of RAM if you wanted. All that aside, something I was told by others at the time was that they were in many ways the 286 that should've been, and if you ran 286-targeted code on them you'd get a really big performance uplift. I never tested that myself, but I can buy it - the 286 was absolutely not ready.

[@shmehfleh3115]

As I recall, VLB was basically just an extension of the 486's bus pins with some buffering thrown in to keep the processor stable. When the Pentium was released, VLB quickly fell by the wayside because it needed extra hardware to translate the 486's bus protocols to the Pentium's. At that point, it just made more sense to implement the platform-agnostic PCI bus.

[@KeyJ_trbl]

@9:30: Yes, there were adapters from the 286 to the 386SX/486SLC bus. The probably most popular one was called "Make-It 486". They were, however, not just (mostly) passive adapters; they contained at least a CPLD and a PAL.

[@mwk1]

Zdróweczko Adrianku 🍷

[@alanharkleroad4376]

Hi Adrian. I feel the same about your motherboard. I have 2 Packard Bell mobos that both suffered Varta damage. Both have the same small chip come off with corrosion. I bought the one in an attempt to fix the other, but that hasn't gone over well. You keep up the good videos

[@TotoGuy-Original]

what a shame it didnt work but them are the breaks sometimes. still worth the watch keep doing these

[@ceebee23]

watched this feeling a bit down with a cold..so sympathies ... hope you are feeling better.... as for the board .....ratssssssssssss grrrrrrrrr

[@falksweden]

This format with OBS and "uncut" it quite nice :) Take care and get well, Adrian!

[@CXensation]

Very good video indeed ! Your experiences here immediately tells me I have to use an external crowbar circuit on the power lines when testing motherboards. The old power supplies are prone to have bad electrolytic capacitors inside. Commonly seen as the top of the caps bulging out or the bottom showing signs of leakage. When the bad capacitors no longer is able to hold a charge the output voltages drops under load causing the regulator circuit pushing the power side to it's limits. - and then disaster strikes ...

[@brycelynch2138]

Holy cats, I think I had that mainboard in my very first PC. The dual VLB slots and the soldered-on 80386 are really familiar.

[@ygstuff4898]

I remember buying my first PC compatible, a 486. The local computer store was selling two with "enhanced" slots: one with VLB and another with EISA. Taking home all the printed documentation and a borrowed Byte magazine (this was before the Internet @ home was a thing), I did all the pros & cons. Eventually, I order the EISA board and all the necessary cards. I must say that my machine was super fast, compared to the run-of-the-mill 386s & 486s at school. Although I didn't like that the EISA cards & BIOS required special software to configure them, but all 8 slots supports 16bit ISA / 32bit EISA. The VLB mainboard only had 2 VLB slots, and the rest were 16bit ISA -- so EISA for the win.

[@kaitlyn__L]

Someone recently went off at me insisting no one used EISA when I mentioned drooling over it enthusiast-ly back then. I was sure there must’ve been the equivalent of today’s Threadripper motherboards for use in the home, they insisted it didn’t happen. Thank you for the belated vindication!

[@freeculture]

@@kaitlyn__L Everything EISA was more expensive, that's the simple fact of it, so it was usually in servers and high end PCs. VLB was sort of a hack, tapping directly to the CPU bus but cheaper to implement. PCI would render both obsolete anyway.

[@samio3907]

Just for the record - I have an old Motherboard from a Compaq SLT386 Laptop which actually refuses to boot without a battery. I would never disregard anything.

[@danaeckel5523]

I had a 586-133MHZ system with VL-B, it was the Image 128 graphics card. Anyways I always had issues with the card popping out of the extended slot all the time. It was a very tight fit, amazing the card nor motherboard never got damaged.

[@linuxdriver]

Thank you because of you i started making diy tech YT videos

[@alain99v6]

i've run VLB at 50 MHz (486Dx50 cpu) it was suppported but finding VGA and multi IO card that were happy at that speed was tricky

[@RealPleak]

At the end, it looks like pins 80 and 79 as well as 75 and 76 are bridged on the 206. It didn't look bridged at the beginning of the video.

[@RetroTechChris]

I remember Alaris from back in the day. Bought a mobo at a computer show once, and the vendor said "they were an OEM for IBM." I guess based on what you found in the search, he was speaking the truth. You've solved a mystery for me... that started more than 20 years ago!!

[@RetroTinkerer]

Hi Chris, search for the video about the Alaris Cougar @retrotechbytes did a while ago.

[@kencreten7308]

Still satisfying! Things happen.

[@AttilaFarago]

Hi Adrian, I had a 386DX back in days and I had experience with this configuration as well. Using a very similar Cirrus Logic card the graphical speed was like half. Not many software used the graphical acceleration that time, but with the SX series it's was like no acceleration at all. On price wise it was a 25% cheaper (the whole PC) but it definitely not worth to save on this boards. This is my first PC was 386DX and I saved on the Sound Blaster compatible 8bit sound card instead. I also tried to save on the Quantum Hard Drive, but that was a failure as I had to replace 3 times in one year. Anyhow I like the video and thanks for your hard work.

[@andyhu9542]

15:23 The VESA spec says the maximum frequency for VL-bus is 25 MHz if there are 3 slots, 33MHz if there are two slots, and 40MHz if there is only one slot. I think this has something to do with signal reflection, or just the load on the bus (in the load case it would be possible to run a 3-slot VL-bus at 40MHz if only one card is present, I don't know whether it is true or not). 50MHz is possible if the device is on-board instead of plugged in using a slot. However, few chipsets support 50MHz FSB 486s, and even fewer of those motherboards have an on-board VL device, so this is hard to verify. Plus, starting from DX2, intel stopped selling 50MHz FSB chips (because few motherboards support that!), the overall performance would be better on a 66MHz DX2 with 33MHz bus than a rare 50MHz DX with a 50MHz bus. Note that these are all guaranteed specs, in real life no one stops you from clocking a VL-bus with 2 cards at 40MHz just like no one stops you from overclocking. The only problem is that stability is not guaranteed outside of those frequencies.

[@freeculture]

That explains my painless experience with the 486DLC and single VLB so it was safely running at 40mhz with the Trident VLB i see...

[@jaredwright5917]

The PEEL18CV8 was a competitor to the 16V8 and other GAL chips. I haven't seen one in several years, not since I lost the only one I had when spilling some chips off my workbench. Their proximity to the VLB slot extension leads me to believe they're part of what makes this work. I know some versions of the 486SLC chips had "System Management Mode" so it's possible it emulates a 32-bit bus using software and extra hardware.

[@TSteffi]

I vividly remember owning such a board when i was a kid. Because it was my very first own PC. A Highscreen branded desktop with 386-SX 16 and a whole 1024 k of RAM. Also a 40Mb HDD and 2 Floppies. But mine had a Phoenix BIOS, not AMI. I also remember that i had to get a VLB I/O card to get the fast UARTs to drive my 14.4k modem. The ISA ones only had 9600 bps UARTs on them. The big advantage was that the VLB ran with the full 16 MHz CPU clock, twice as fast as the ISA slots. And if i remember correctly, the CPU handled the two busses separately. That way my fancy terminal programs screensaver didn't mess up my Zmodem downloads anymore.

[@poepflater]

What a beast, my folks had me contribute my life savings in grade 5 to buy a 286 SX, was it 16 MHz?. I remember the video card had pin sockets wit unoccupied chips so you could add your own 512k memory...

[@thehighwayman78]

This was entertaining nonetheless! Thank you :)

[@maxtornogood]

Bummer, I was hoping you'd be able to save it!

[@mogwaay]

Sorry board got fried, that can't have helped you current cold! Thanks for uploading anyway, helps to see that sometimes even you can have issues like this.

[@davida1hiwaaynet]

Wow that is frustrating having a PSU destroy good hardware! Thanks for proceeding to share it with us even though it ended badly.

[@MIJ-Tech]

I had a PSU go bad while working on my parents' IBM PS/1 Consultant years ago that took a video card (ATi Mach64 ISA), network card (D-Link DE-220), and motherboard with it. Whatever voltage spike went through the system was enough to crack the main chip on the video card. The computer would still POST with another video card, but when in the BIOS setup, every other character was scrambled. It was a very sad day.

[@ToxicwasteProductions]

We watch these videos because we always learn something. A bad board sure it's sad but things happen and sometimes things go to shit. I have a idea what have maybe killed the Cpu. When you lifted the board and it stopped beeping a few times in thinking maybe some pins on the back made contact with the case of the psu. Anyhow I love your videos you are awesome. Keep it up and I'll see you in the next one. Cheers from Sweden

[@suvetar]

I like the format, keep it up! Sorry about your Mobo!

[@Ghozer]

When you zoomed in on the opti chip, it looked like there was some rogue solder or something bridging some pins further along the edge (bottom edge, to the far right, near the corner.. as looking on the video) and then also, the larger chip above, the bottom right corner (again as looking from the video) - looked like there was a rogue piece of metal or wire going from the via or something...

[@Hiraghm]

Last week I had a headache... then a headache and a sore throat... then it turned into a full-blown headcold that I'm still fighting. It's out of my sinuses, now, but lingers in my lungs. So you might have another week ahead.

[@rodgerries6582]

Thanks!

[@adriansdigitalbasement2]

Amazing thank you so much for the super thanks! I've been fiddling around with this motherboard some more but unfortunately nothing jumps out as faulty. That blasted PSU!

[@iamdarkyoshi]

Might be worth looking into some sort of crowbar overvoltage protection circuit that shunts all the rails if one of them goes out of spec

[@KF7PCL]

Or even a zener and a fuse on each rail

[@Lukeno52]

Might be worth going around some of the components and seeing if you can find any obvious shorts and see if it is as simple as just a couple of shorted capacitors or resistors.

[@phillipmullins1643]

Interesting content as usual and you do a great job of explaining what you present. I have a question nonetheless. How is Portland surviving without a local Walmart?

[@MrKillswitch88]

Boards of this vintage usually don't get my interest often but this is one of those rare examples that I didn't know existed not that VLB 386 is new to me but for the SX wasn't expected at all.

[@DJLKM1]

Im sure i saw some bridged pins around pin #80 on the opti package. other than that im empty. Great video anyhow as always :)

[@AllanSavolainen]

When I see VLC buses on 386, I usually check first that they are actually Vesa Local Bus and not Orchic Local Bus and other Local Bus from the same era (same connector, different pinouts)

[@vitajazz]

My first Pentium computer was (someone else's) homebrew with a Canon Pentium 66 motherboard with ISA and JUST Vesa bus, no pci. It was a dog, hardly faster than my 486DX, 100 I think, also with VLB. I eventually sold the Canon MB to a fellow for $200, way more than it was worth, because he was a collector of rare and unique computers and components.

[@the_kombinator]

I just sold an IBM Blue Lightning SLC with VLB - it was also a 16 bit processor at the core. I've seen 386 SX VLB mobos, albeit with a socket 3 upgrade path.

[@bluebirdpod]

Oh Boy!, this video brings back my early memories of PC days of working for a Clone-PC company, and yes there were some very cheapo motherboards, and as posted below the chinese card makers used very sloppy insertion specs and the cards could move front to back inside the slots, you had to line up the pins yourself and then push the card down into the slot, and sometimes it would move between pins and not post. Oh was I glad when this died off, then PCI bus, and then the kinda lousy AGP slot era. it was a bandaid ontop of more bandaids, and most just were regular cards that you could put in a VLB or AGP slot and no better performance was noticed. a lot of problems go away when you put MR Bios on these old boards if available VOGONS has a zip file with a ton of Mr Bios files.

[@freeculture]

Main issue was lazy people not using all screws for the motherboard (or the case not having enough points). So yeah it needed perfect alignment and careful handling, very useful to always recheck/reseat everything before turning it on which isn't exactly user friendly.

[@StrapMerf]

I used to own a 386 server board pc.. the actual processor and ram were on a daughter board with VLB... the motherboard had 3 slots for VLB boards (1 for the processor board)

[@Deckmaster]

With the finding of the broken wire to the OPTi chip that makes me think the beep was actually 1 beep short repeated.

[@gbclab]

1996: I had a 486 MB with 3 PCI bus plus ISA. My processor was an excellent AMD 486 DX4 120 MHz.... Great times, great memories

[@retrozmachine1189]

Tracking the power-good trace from the PSU might be us... haha, I was typing this while continuing to listen to the video and there you go. It was that being part of the problem. Next thing I would verify that is present is the osc is running.

[@the_kombinator]

Leopard might be an Alaris SLC board. Had a very similar one up until about a week ago. You're looking at an Alaris 33 MHz 486 SLC with a 16 bit external data path. I made a video about a similar computer years ago.

[@Drew-Dastardly]

When I finally switched from my souped up Amiga 1200/030 - I specced up a 486DX2-66 with VLB for SVGA graphics and hard drive cards. Good times for the very short lived VLB!

[@freeculture]

When i moved up to a Cyrix 486DX4 100 the motherboard had two VLBs, i brought my trident VLB and added an IDE/floppy VLB to it. Conveniently it was 3x 33Mhz so the 33mhz for two VLB cards as the spec says, neat. I think it was win 3.11 that could use 32bit ide.

[@dintyshideaway9505]

This is a very interesting period in PC history. The VLB standard was very strange anyway. The cards never fit, and the drivers almost never worked. I remember the Diamond Viper being the component that would best take advantage of the standard, and I had one that worked maybe 50% of the time. Most people had a Cirrus Logic 5xxx card in VLB, and the many VLB controller cards which I never really noticed a speed difference with. You are right about the SLC chips being a very misleading standard. John Dvorak famously lambasted IBM for putting their name on them. Of course this was IBMs revenge on the whitebox market by dumping all the motherboards with SLC chips in them, after the failure of their Ambra brand. I had a couple of those boards, the 32 bit models were known as "Blue Lightening". I suspect this board was intended to be in one of the odd Ambra models that had both and SLC chip, and a VLB slot.

[@the_kombinator]

LOL - I have built over 50 retro PCs recently for sale on eBay with VLB, the cards fit and the drivers worked. The only occasional issue is that some VESA cards don't work in certain slots, but I've never had issues with them, even back in the 90s. Hell, I had a DX-50 486 running with VESA I/O and a VLB video card, as well as a Socket 4 P60 VLB running Windows ME back in the day. The drivers are available now, and they were included back in the day on diskettes. Stop dogging VESA. Also, "lightening" ?

[@davidhollfelder9940]

I had a 486sx w/ math co & a VESA video card. It had higher video resolution (800 x 600) compared to my former ISA VGA. I didn’t notice much, if any speed increase.

[@JBEEUD]

I've actually got a stack of those boards that came from little IBM PS/2 computers. They all have some level of battery damage, though some not so much, but at some point I'm going to be getting rid of them. So ya, I'm not surprised that they came up in your search as being associated with IBM.

[@rager1969]

For those that are learning from this video, the 386SX isn't a 286 with extra signals. As it is correctly said later ,it's a 32 bit 386 CPU internally with a 16 bit external data bus, whereas the 286 is 16 bits internally and externally and is missing 386-specific CPU instructions (of course).

[@stevenwilson1690]

The BIG difference between the 386 and 286 was Virtual memory. The 286 was BROKEN as far as its Memory Management was concerned. On 286 when you went to Virtual mode - you couldn't get BACK! That is a big problem for an OS that needs a Kernel Mode and User Mode to support secure operations. The 386 fixes this - and a 386SX has that feature! So it isn't JUST another version of the 286. Back in the early days of Linux I was running Linux on a 386SX an 8MB of memory. I was running X Windows on it and it was perfectly peppy!

[@dougjohnson4266]

@stevenwilson1690 Sometimes I think ADB and others say these things about the 386SX, 68000 and the 8088 just to get people to comment.

[@the_kombinator]

In the same way, would you consider a 486 DLC (132-pin PGA) a degraded 486, or an enhanced 386?

[@dougjohnson4266]

@thekombinator617 From my understanding, the 486DLC was a 486SX compatible processor, and the 486SLC was an 'enhanced' 386SX. (A marketing ploy calling it a "486SLC".)

[@the_kombinator]

@@dougjohnson4266 The Cyrix 486DLC and the Ti counterpart (more cache on that one) are PGA 132 CPUs with 486 instruction sets added. Neat little extension of the 386.

[@UpLateGeek]

You can definitely upgrade a 286 machine with a 386SX. I've got an IBM PS/2 model 50 with a Kingston SLC Now! upgrade, which is a 386SX plus some extra chips. Thanks for the tip about the retro web website, I hadn't come across it before. That motherboard search looks really useful, so I'll keep it in mind next time I need to get some details on an old board. Anyway, that's really bad luck with your power supply. But I guess it's better that it failed on a weird random board rather than something more noteworthy.

[@roygillotti4615]

Reminds me of those later 486 motherboards with PCI slots, had a friend that bought my first Voodoo card and had it running on that, could even play Half-Life, well a bit poorly.

[@Knogle2]

This is why I don't like using old AT power supplies, but use ATX's with AT adapters, the fear they'll fail and take hardware with them. Same with original C64 power bricks. But I don't have wizardry repair skills either, hence I'm extra cautious and in awe of those who's got em' 🙂 Regarding 386SX, I think along with more MHz, it's also got double the amount of transistors, so still quite beefy compared to a 286. But would never have guessed it existed with VLB either. I hope you feel better Adrain, and thanks for making and sharing the video despite everything 😊

[@brandonupchurch7628]

I don't like AT supplies because they typically route mains voltage through the case to a switch, I've had a machine I was working on where the front switch was either replaced by a moron or the factory subbed a switch they shouldn't have, but it had solder lugs on it instead of straight terminals for spade connectors, so the switch wires had enough wiggle room that one of the leads managed to short against the bracket holding the switch and threw a nasty arc and flipped my breaker, I think I got a little bit of metal in my eye from it too, so I don't like messing with AT supplies at all because of it.

[@burnte]

The differences between the 286 and 386SX were a lot more than a few lines. Protected mode worked, it was 32 bit internally so could run 32 bit code (unlike the 286) but had a hobbled data bus to 16 buts to make it cheaper.

[@pelgervampireduck]

I tested local bus vs pci on a 486 SX 50mhz (so basically a 386, and I guess the bus was running at 25mhz with a multiplier of 2). The game Screamer has a "test your graphics card speed" option. I don't remember the numbers but the PCI card was faster than a local bus card. Both had 1mb, the PCI card was a Cirrus 542x or 5430, I can't remember, the local bus card was a "chips 64300" (the drivers in Windows called it "wingine").

[@KikuVasNormandy]

My first personal machine was a 486 with a board that used local bus, I still have the video card and IDE card from that machie. Sadly I cannot speak too much about performance since 1. I was very young and didn´t understand much at the time and 2. Never have a sound card on that machine (and SVGA monochrome monitor), so never used too much to play anything aside some really old DOS games.

[@kuromi_oficialYT1234]

The Alaris Leopard, i have the same card with a 486SLC2 66MHZ ibm cpu. It can run at 80 MHZ by playing with the jumpers in an undocumented setting. I recently got a VLB card and will test if there is an improvement with it.

[@gregoryp203]

IIRC this motherboard was sold at b&h photo. It was a dirt cheap 486 motherboard and I was almost going to buy it but upgraded my 386sx with the cyrix piggyback 486slc. That is when I realized the cheap IBM 486 motherboard was a 486slc not a real 486

[@StrikeValkyrie]

The first computer I ever put together for myself (after being pretty badly ripped off buying my first PC, an essentially useless 286, from a guy at the mall just selling a computer at a table) was with a 486 SLC. I found a motherboard for sale in a catalog that had the processor already seated and thought the specs sounded good enough. I worked a lot as a teenager and ended up buying a pretty high end VLB graphics card to use the extended slots. This was all so I could run Mortal Kombat so that program was the benchmark. It would run great for a few minutes but would always lock up no matter what I did. I think I even remember the requirements for the card exceeding my system specs although I bought it anyway. I thought that SLC stood for 'Single Line Com', although I may be remembering that incorrectly. It ran everything else fine, though. I had a lot of fun with the system. The 286 I sold to a friend who insisted that I sell it to him although I assured him that it could play nothing but older games and had to emulate color. It came with a small monochrome monitor. The seller gave me a disk to boot the system and one to emulate Hercules CGA graphics. I think he included a copy of Pharos Tomb. I sold it to him and used the money to buy a VGA monitor and the first parts to my new system. Eventually I had a nice gamepad, sound card, graphics card, etc. and put it all together myself. I got Saturday detention a lot which was held in the high school library. I would go to the job finder computers in the back and reset them then enter DOS to play games I would sneak in from home. I remember the librarian catching me playing a demo of Desert Strike and being surprised that the computers could be used for anything other than the job finder program. I explained to her that it was just a computer and that it had DOS and Windows although nobody ever used them for that. I even showed her 'CTRL ALT DELETE'. She was not angry with me in the slightest but rather impressed. I later brought blank disks in and copied Windows and DOS for my own use. This was back when Windows often was laughed at for being useless and I would complain about how DOSSHELL was better if someone really needed to click on icons. Since then I have made so many computers and done so much with them. It all started with a 486 SLC. 😎

[@krz8888888]

Power supplies killed so many computers back in the days!

[@SenileOtaku]

I remember seeing some systems that came out *before* the VESA Local Bus that included various sorts of proprietary bus extension slots. I suppose one of these got enough industry backing that it became VLB (some of the ones I saw looked much like the VLB). If I knew where my CompuServe email archives were I could look up when it was, since I had emailed John Dvorak asking about them. One of my VLB systems also had a drive controller that plugged into the second VLB slot, and took regular 30-pin SIMMs to add cache to the controller. Now I wonder just what happened to all these boards and such when I upgraded them (I haven't seen them since even *before* our house fire, which is where I lost a lot of old components).

[@Quickened1]

I can tell this is your second channel from the static in your hair! 😂 Feel well man...

[@teg24601]

Interesting about the number of SIMMs. I grew up with a 386SX, and it had 4 SIMM slots, and we actually populated it with 4 1MB SIMMs, which were entirely readable. It was capable of 16MB, with RAM expanders or 4MB SIMMs, if you could find/afford them.

[@dhonzik]

VLB 2.0 was released in 1994, with a 64-bit bus, and a bus speed of 50 MHz. So with the Pentium 64-bit data it was able to use the later spec, but with PCI coming out for the Pentium VLB went out of favor

[@januszkszczotek8587]

Two thoughts on the board: 1) is it possible that the different pitch of the beep codes with and w/o the video card was already sign for a short or problem in the PSU? 2) AFAIK use of the 32bit extension on VLB cards was optional, i.e. if the card is inserted into a normal ISA slot, it still works, yet slower. Therefore the VLB slots on this board might be just for better physical support of a VLB card - probably only connecting ground pins of the 32bit extension.

[@michaelhall4626]

My Dad's school had some 486SX-25s with VLB (DEC LPV) and 486SX-33s with PCI (DEC Venturis), although I don't think I ever compared I/O speed on them. Also, the IDE controller in the LPV had a silicon bug that could cause data corruption if used in 32-bit mode, anyway.

[@intel386DX]

Very strange biard ! VESA slots usually are only on 486 boards

[@TheFurriestOne]

I'll have to check the VLB board I have in the garage, see if it's 486 or 386.

[@spagamoto]

Just thinking it might be a good idea to make a little crowbar protection board for future projects... just a PCB with a crowbar circuit on each power rail that sits between the PSU and the motherboard.

[@kevin34ct]

I actually have a Pentium MB with VLB on it. I have a 200MMX om it with a Sound Blaster AWE 32 VLB board.

[@evileyeball]

I had 2 different PSU's die on me in my first PC build One lasted me from 2008-2015 and the replacement worked from 2015-2018 Both times they died I was lucky and nothing else got damaged by them.