Octek Fox-286 with Headland chipset.

Octek had couple of hits with their hardware back then.
286 Headland chipsets were very common ... and just as much unexciting.
So, i was not sure what to expect here.

The board is of good quality. Had to solder a crystal oscillator socket.
Takes up to 4 Mb of RAM. Used 4x1 60ns sticks.
DIP switches provide control over 0/1 wait-state and RAM configurations.

At 0 wait-state 16 MHz is the limit. Above that the board does not light-up.
At 1 wait-state things go as high as 27.5 MHz, fully stable.

https://www.petershipkov.com/temp/retro_pc_im … motherboard.jpg

The usual set of stats and benchmarks:

Conclusion:
An average board without unique features.
In search of positive comment i am arriving at - 30 years later it still works.

Something different.

I have been slowly setting up a clean 1994 486 VLB system, but had some doubts about the casing.
Never owned branded PCs. Custom builds all the way, tuned for maximum performance. All bells and whistles removed - only the essentials left.
The standard metal cases were always a point of annoyance. Lids were rarely closed, many internals removed for convenient access to hardware.
So, when the retro bug bit me a while ago, i started looking for a proper alternative to the big-bulky-clumsy cases - i have a fridge in the kitchen already. 😀
At the end i decided to make a 3D printed PC case to my liking: austere and functional.

Requirements:
- simple shapes that can be easily augmented into other designs
- easy to print objects
- economic on filament - fit within 1 and a half spools, including some reprints
- structural strength
- easy to assemble
- functional and easy to use
- compact

Ok, here goes nothing:

As i said - design is minimalistic.
I stopped using HDDs and moved to CF cards long ago, so there is no holder for HDD in there, but space is allocated on the side of the PSU separator, if one day i decide to go back to HDDs.
The design allows to easily add/remove the PSU. Reason is - i have more systems than PSUs. When want to fire-up one of them i grab an available PSU and play.
Ventilation is secured by the PSU - sucking "hot" air from the inside and expelling it.

There are countless brands and types of 3D filaments. Most of them are not great, but there are few that are just right.
My 3D filament of choice is Polymaker PolyLite PLA 3D, 1.75mm, temperature 220/70:
https://www.amazon.com/gp/product/B01IAVQIWE/ … 0?ie=UTF8&psc=1
It is the easiest thing to print with using Prusa I3 MK2 (and later models) - precise clean shapes, does not bend at all, sticks really well - you can literally print on a cookie and it will be fine.
My first pick was natural transparent filament, but wife said "looks old at first sight", the printing quality was superb.
Black looks cool, but absorbs too much light and the case gets too dark on the inside. This compromises the requirement for "functional", so ended up going with white filament. Next time when I drop a screw by accident inside the case it will not be lost for good 3 minutes.
Anyhow.

Everything needed for the case - bunch of printed parts, couple of screws, "reset" cable, Loctite glue.

The "reset" button consists of 4 pieces + cable. The contact surfaces that will be glued together required a bit of smoothing - scraped them few times with a knife.

The slot for the PSU's power switch. Took some trial and error to make a design that allows easy insertion and removal of the switch, but keeps it tightly fit while inserted there.

The individual panels glued and drying for few minutes.

This is perhaps the most tricky part of the whole assembly - the screw sockets for the motherboard.
I have printed markings on the bottom panels indicating where the slots should be glued, but wanted to double check in case my blueprints were off.
Inserted the back panel into the corresponding slots and placed the sockets.

Put the motherboard on the screw sockets. The two inserted cards helped me position the mobo precisely in the right place.
Notice the green sharpie with extended graphite.

Used the sharpie to mark the places of the sockets. Turned-out my printed markings were correct.

Test assembly - inside. Don't pay attention to the messy cables, this will be sorted out later on.

Test assembly - outside. Didn't spend time to completely fit all panels, that's why they look a bit dislocated, but In fact the panels fit and hold onto each other so well that the case can be used like that without further gluing.

In case any of this is interesting to you - here is the blueprints (Maya ASCII format), triangulated OBJ files, factory file (Simplify3D), gcode files ready to print:
https://www.petershipkov.com/temp/retro_pc_im … _at_pc_case.zip

Leaving the final assembly for the next post, when the 486 system is in complete order.

That' really cool. Love it.

I like my 486DX5 PCI/VLB/ISA PC from page 1 a lot, but my purist nature has been growing on me and i ended up building a clean VLB system from year 1994.

HARDWARE

• motherboard: ASUS VLI-486SV2GX4 rev 2.1, 1024Kb 10ns L2 cache
  cpu: Am486DX4-100V8T 120MHz
  • AMD-X5-133ADZ 160MHz
  ram: 64Mb 60ns parity FPM (Micron - the picture below is old and shows 2x16Mb, instead the current setup with 4x16Mb)
  vga: ARK1000VL 2Mb (primary)
  • Diamond Stealth 64 DRAM 2Mb (S3 Trio64)
    S3 805 1Mb
    Paradise 2Mb (WD90C33-ZZ)
    Tseng Labs ET4000/W32i 2Mb
    Trident TGUI9440AGI 2Mb
    Weitek Power 9000
    Cirrus Logic GD-5428 1Mb
    Orchid Kelvin 64-VLB 2Mb (Cirrus Logic GD-5434)
    Avance Logic ALG2228 2Mb
    US Tech TK-85C418VIO 1Mb (UMC UM85C418F-GP)
    OTI-087 2Mb
  scsi: Adaptec AHA-2840/42A + UMC multi I/O card for ports
  ide: Promise EIDE2300 Plus
  audio: Sound Blaster 16 CT2230
  lan: 3com EtherLink III
  psu: 450W AT
  input: BTC 5121, MS IntelliMouse 1.1A
  os: DOS 6.20, Windows 3.1
  partitions: 1x504Mb

NOTES

This build was less straightforward than expected for 3 reasons:

Initially i wanted this to be an Intel CPU based system, but had to switch to AMD to achieve complete stability at 120 MHz.
Intel's 486DX4-100 CPU running at 120 MHz was fine for the most part, but failed the 3D rendering tests.

The situation with HDD controllers was more hairy.
Obviously i couldn't go with ISA SCSI/IDE controllers for this rig, so i had to choose between SCSI Adaptec AHA-2840A and bunch of VLB IDE/EIDE ones.
Adaptec AHA-2842A operates in 10 Mb/s setting and achieves ~7.2 Mb/s read and 4Mb write speeds - not bad, but some of the EIDE adapters around that time spank it on performance. Also, the problem with this guy is that it uses bus mastering. Things work well with the DX4 CPUs because they do not use WB1 mode, but if i decide to switch to AMD DX5 CPU for example, i need to either disable the WB1 cache with jumper/bios, or use an EIDE adapter.
I wanted to find the best option, so i spent a moment to test couple of VLB IDE/EIDE boards. This revealed interested details that i will post at some point later. The best performing and most stable EIDE VLB adapter was Promise EIDE2300 Plus, so it was given the honor to complement the rig. Driver in DMA mode, speed 8 (highest). It is worth mentioning that it works just fine in DMA mode with POD CPUs + L1 cache in WB mode - something not all VLB EIDE controllers can brag about.

I had to make some "difficult" decisions about VGA adapters.
There are quite a few good ones in the pack.
In Windows things are very simple - S3 Trio64 then the rest. In 16 bit mode it starts to even take on Matrox Millennium PCI.
In DOS Ark1000VL is the fastest thing around followed an inch behind by S3 Trio64.
At the end i went with Ark1000VL, because this is more or less a DOS PC. Other than few Win3.1 apps - there is little else for me there.
Will provide in subsequent post the collected performance information about VLB/PCI VGA adapters.

Getting the system maxed-out with 64Mb of RAM and 1024Kb of SRAM + WB2 mode was a real challenge.
I had to comb through a lot of cache chips to find 9 that work well.
So far so good, but i have this nagging suspicion that when in WB2 mode things may not be solid 100% stable.
Looking for ways to prove that ...
EDIT: Few months passed already and the system is just solid. Ok, i was not able to prove it unstable, but gladly accept the result.

There are mild differences between revision 2.1 and 2.0 in the upper right corner, related to CPU voltage control.

Will not post pictures of the rest of the VLB adapters here, they are already shown on the first page of this thread.

486DX4 at 120MHz with Adaptec AHA-2842A

How things look in the physical world:

-----------------------------------------------------------------------------------------------

Tested the system with AMD-X5-133ADZ running at 160MHz with Promise EIDE2300 Plus and Transcend 133x CF card, which is highly compatible with this class hardware (no write access issues and other nonsense).

-----------------------------------------------------------------------------------------------

I couldn't resist to check how this clean VLB system compares against two other champs:
Biostar MB-8433UUD-A (ISA/PCI) - one of the fastest 486 PCI boards in terms of VGA performance (despite some stability issues, 3D rendering, etc.)
Asus PVI-486SP3 (ISA/VLB/PCI) - what i consider the Maybach of 486. 😀

Matrox Millennium seems to be the fastest PCI card until the end of year 1996, so i picked it for this comparison.
Used Ark1000VL as a VLB representative, included S3 Trio64 for the Windows test only.

Linking here the composed benchmark results as well.

VESA local bus video cards have clear advantage in DOS, but lack in Windows.
As i mentioned above already, will try to post the full stack of VLB/PCI VGA perf data in the coming days.

Asus PVI-486SP does really good job at squeezing the most out of the CPU - the best i have seen among 486 mobos.
So i am not surprised that it outguns the VLI board at the 3D rendering tests by quite a margin.

At the end of the day, i am still flip-flopping with this rig between 1994 486DX4@120MHz+SCSI and 1995DX5@160+EIDE.
It feels like it will be an 1995 rig at the end of it, which means that i will need to get back to making a 1994 one at some point later - not a bad thing to look forward to. 😀

The Asus VLI-486SV2GX4 story evolved with AMD Am5x86 processor running at 200MHz (4x50)

Very nice job, impressive.

For best performance with your SV2GX4 you should activate the dirty bit in your BIOS in L2WB. Therefore you have to modify some registers and update your BIOS. The official BIOS doesn’t support dirty bit.
The Am5x86 runs well with L1WB together with the AHA2840 (2842 is the version with Floppy). Make sure you run the newest BIOS on your board and close the Jumper J5 on your 2840.

A pro tip.
I remember reading with great interest your thread Evolution of a Socket3 System to a POD @100MHz about that stuff.
I use the BIOS you mentioned already, but at the moment J21's pins 4-5 get shortened for WB on the motherboard all bets are off for IDE bus mastering, regardless if J5 is open or closed on the SCSI controller. Or do i miss something here ? Let me know.
Thanks.

Try the Jumperset for P24D and add the following jumpers:
JP16: 1-2 (important for the CPU Voltage!)
JP20: 1-2 (multiplier 4x)

Always close the J5 on the 2840.

Try to toggle JP26 between Delay and Non Delay
Try to toggle between the VLB slots

I got L1WB stable on my SV2GX4 without DMA problems with the following CPUs: Am5x86 (BGC), AMD DX4 SV8B, Cyrix 5x86, intel DX2 66 (P24D)
With DMA problems (Floppy and/or SCSI access) or not working with L1WB: Pentium Overdrive (P24T), intel DX4 WB (SK096)

The 3D printed case is very impressive. I wouldn't have been able to design something like that, at least not currently! I also just bought a Matrox Millenium for the same reason. Will continue to watch this thread with interest.

@PC-engineer
This is how I have the jumpers already.
I bet it is an Acard scsi2ide adapter issue (stopped using HDDs long ago).
Will strap a scsi drive to verify.

@pii_legacy
Yeah, the case turned out pretty ok. Glad to see you like it.
Matrox Millennium has two flavors. The main chip on some of them ends with R2 others have R3. Usually the ones with R3 have the latest BIOS which makes a small positive difference for performance in some cases. You can also upgrade bios manually, but the DOS utils for that are not great.

It looks like this is Acard scsi2ide related issue that is not present when using SCSI HDDs.
For now i will let it slide, since the problem does not affect the WT AMD 486DX4 CPU in use.

While assembling the clean VLB 486DX4 PC from my previous post, i spent a moment to check how VLB and PCI video cards from 1993-1996 compare against each other.
In addition - there were some discussions on the forums about that, which further fueled my curiosity.

I have a bunch of 486 motherboards, few of them mentioned in previous posts in this thread.
From the pile i picked the best VLB, VLB/PCI and PCI ones:
Asus VLI-486SV2GX4 rev.2.0, 1Mb 10ns cache, 64Mb 60ns
Asus PVI-486SP3 rev.1.22, 512Kb 10ns cache, 128Mb 60ns
Biostar MB-8433UUD-A rev.2, 512Kb 10ns cache, 64Mb 60ns
AMD DX5 running at 160MHz, 40MHz FSB.
All BIOS settings optimized for best performance (lowest wait states, etc.).

The list with tested video cards:

• [PCI] Matrox Millennium MGA-2064W-R3 8Mb
  [PCI] Power Color C64/V2 2Mb (S3 Trio64V2/DX)
  [PCI] Compaq S3 Vierge/GX 2Mb
  [PCI] 3DFX Voodoo 4Mb
  [PCI] Tseng Labs ET6000 4Mb
  [PCI] Tseng Labs ET4000/W32P 2Mb
  [PCI] Prolink MVGA-CL548XP 4Mb (Cirrus Logic GD-5480)
  [PCI] Chips 65554 4Mb
  [PCI] Trident ProVidia 9685 4Mb
  [PCI] Diamon Stealth 64 2001 (ARK2000PV) 2Mb
  [PCI] Diamon Stealth 64 VRAM (S3 968) 4Mb
  [PCI] SIS 6202 2Mb
  [VLB] ARK1000VL 2Mb
  [VLB] Tseng Labs ET4000/W32i 2Mb
  [VLB] Diamond Stealth 64 DRAM (S3 Trio64) 2Mb
  [VLB] Orchid Kelvin 64-VLB 2Mb (Cirrus Logic GD-5434)
  [VLB] S3 805 1Mb
  [VLB] Trident TGUI9440AGI 2Mb
  [VLB] Paradise 2Mb (WD90C33-ZZ)
  [VLB] Weitek Power 9000
  [VLB] Cirrus Logic GD-5428 1Mb
  [VLB] Avance Logic ALG2228
  [VLB] US Tech TK-85C418VIO 1Mb (UMC UM85C418F-GP)
  [VLB] OTI-087 2Mb

Pictures were posted in previous posts in this tread, so won't duplicate them here.

https://www.petershipkov.com/temp/retro_pc_im … rks/vlb_pci.png

Long story short - VLB video cards have advantage in DOS, but fall behind in Windows.
Ark1000VL is consistently the fastest graphics adapter in DOS.
Matrox Millenium is the the fastest in Windows, but notice how S3 Trio64 VLB in 16bpp mode gets dangerously close there. 😀
This test is also an indication about how clean VLB, clean PCI and VLB/PCI motherboards handle graphics.

@PC-Engineer

Spent a moment today to check what is happening with this VLB SCSI + WB1 business.
Long story short - for this to work 3 things need to be in place:
- the WB-enabled BIOS, obviously
- despite using AMD DX5 CPU, jumpers have to be configured for P24T with J20 set to 1-2 for 4x multiplier = 160MHz
- because i use Adaptec AHA-2840A (the one without on-board floppy controller) an IDE card with FDD controller needs to be present otherwise the Adaptec guy won't boot the OS

#3 paused me for a moment 😀
Back when i bought the SCSI controller i had the option to get the 2842A version, but since i would need an I/O card for mouse which comes with HDD/FDD controllers as well, i opted for the slightly cheaper 2840A.

One less puzzle around here.

ok, so, upon closer inspection and profiling the outlined above configuration is not completelly stable.
it works most of the time - for example - Doom, quake 1, some apps, etc. seem to be fine, but wolf3d and dune2 can hang the system. i am sure there will be other cases too.
bummer.
rolling back - stability must be complete.

ran a search, there are 2-3 threads about this subject but kind of inconclusive - didnt get the sense that the configuration was throughly tested.

If you use more than one VLB card with 40MHz the transparent mode gets buggy. Also switching JP26 (D-ND) can help.
And i found out long term stability issues (sporadic crashes) with the 10ns ISSI 128k8 chips (several batches from several vendors) at clocks over 33MHz. The latencys didn’t matter, only time (>30min running) and clock (>33MHz). Double checked it with other boards with the same behavior. Also a active cooling of the chips didn’t help. In the end i switched to 512kb cache with 15ns 64k8 chips from UMC.

Thanks for the info PC-Engineer.

To confirm for the record:
Assuming system configuration: AMD BGC 160MHz WB1 CPU, 40MHz FSB, 1024Kb 10ns ISSI SRAM (had to go comb through bunch of chips to find the right ones), VLB VGA, tightest BIOS timings, transparent mode.
VLB IDE + WB1 = long term stable.
VLB SCSI + WB1 = unstable.

But since this system is targeting year 1994, it is using AMD DX4-100 WT1 CPU, which means that all of the above VLB SCSI+WB1 specific issues are not present.

You can use your Am5x86 as a DX4 100 with 3x 33MHz to „emulate“ the AMD DX4 100, so you can keep it installed and switch between the classes. The AMD DX4 100 arrived the marked in the end of 1994 the intel DX4 100 in Q1/94. The intel has some improvements over the AMD, one is the better compatibility for clock sensitive applications.

Maybe you can try a last test with your SCSI controller and 33MHz FSB. If it is stable than the root cause is the overloaded VLB @40MHz with two cards. In this case you can try another combination (switch the ports, or take other cards) of the both VLB cards. For an overclocked VLB it depends on several (small) factors to get it stable.

And the effect of L1WB is overrated for real 486 CPUs and a sufficient amount of L2WB cache. Maybe it is better to drive L1WT and accept the 0...1% performance loss and keep the nice SCSI controller.

Made a mistake in my last reply - the system is targeting year 1994 as stated in the initial post, but not 1993. Thanks for pointing out. Fixed it above.

I measured the WT1 vs WB1 perf diff carefully - it varies within 1-4%, depends on the app/game.
It totally makes sense to switch to WT1, as you suggested, and trade the few percents of compute/graphics performance loss for 2Mb/s disk speed gain, but the force of irrationality is strong with me - these few extra % are more valuable than the significant gain in hdd speed, so there goes the VLB SCSI. 😀

Good point about 33MHz FSP - it will be interesting to see what this does to it.

Did you have this project for ATX and mATX sizes?

I don't have a ATX based design, but the current one can be adjusted easily.
ATX PSUs dimensions tend to be more volatile than AT ones - this will dictate case size.
Do you have a particular PSU in mind ?
The only thing that will need a bit of attention is to replace the AT switch slot with something that fits an ATX one.

I am going to dump here info about few more motherboards and other stuff.

ASUS ISA-386U3Q

An old new stock. Squeaky clean, manual, wrapping, etc.

This seems to be a 1993 model. Visually the motherboard looks great - tight and well organized.
There are pretty much no jumpers on it. There is one for the FPU, 2 for the cache configuration and that's pretty much it.
The BIOS lacks any sophistication - there are 3 parameters related to performance that can be set to "fast" or "slow".

It is a bit picky about memory. Had to try few different sets to find the right ones for it.
However its biggest drawback is the inability to handle properly CF cards. Concerning.
As a workaround i strapped a SCSI adapter and all was fine from that point.
The SCSI operates at 6.7Mb/s, which is not exactly stunning for 50MHz FSB.

The board overclocks to 50MHz with FPU and things are stable for DOS gaming, but for 3D rendering and in Windows i had to step down to 45MHz for complete stability.

Didn't bother running LightWave3D rendering test. It takes about 3 hours to complete and won't reveal anything surprising.
benchmark results

Conclusion:
I had high hopes for this motherboard, but it didn't quite hit the mark.
Issues with RAM, issues with CF cards, performance is so-so.
Otherwise it is a real looker. Not sure if pictures give it a justice.