Way before CPU galaxy's video was this link detailing the DLC/SXL settings, Register settings for various CPUs It goes into much more detail.

Mine also refused to work with a 16 Mhz FSB when I first tested it. Either the system didn't like the 3-chip memory I had installed, or somehow the presence of the FPU allowed it to 16 MHz FSB. When I first tested it, 12.5 MHz was max. Not any longer.

Yeah, it looks like aliexpress has the 87SLC-33QP chips for $10. I'm not sure if they are fake. I'll report back when mine arrives. I plan on doing more testing with the -v25 I have on there now, but upon initial tests, the surface isn't getting hot. It was only $5, so not much loss to replace it.

According to Anonymous Coward, the non -v and non-g50 SXL2-40's should also be 5 V, so I might try this as well. Also, the SLC2-25/50 should be 5 V and might be worth testing. According to Anonymous Coward, they are locked in clock doubled mode. Cheapest I could find is $57 each from China. Not sure if they are authentic or not. Best would be a desolder, but I couldn't find any.

I've given up on the 286 no floppy boot issue. I plan to use the SuperChip anyway. I have an LS-120 BIOS I might try on a Lo-Tech card, but my LS-120 is sitting at AVICC, so cannot test it yet. But this might allow for 286 booting on the floppy.

I've been run the Evergreen 486 SuperChip with SLC and 87SLC at 33.3 MHz for about an 90 minutes now. No issues. I've let FPUTEST run for over 20 minutes and it hasn't crashed. FPUTEST is some kind of DOS fractal generating program. The surface of the FPU reaches 42 C max. I then ran a few basic benchmarks using a Tseng ET4000AX graphics card.

SLC-33
3DBench scores 14.2 fps
DOOM scores 12609 realtics, or 5.92 fps

The results seem pretty poor, so I compared them with a DLC-33 on a 386 motherboard with 256K cache. My 386 results are from my past notes and were tested with a different graphics card, the GD5434. Fortunately, the difference between GD5434 and ET4000AX is less than 1%. For whatever reason, the GD5434 and ET4000w32i won't run on this system. Anyone know why? ET4000AX and ATI Mach64 w/4MB both work.

On a fast 386, SiS 310/320/330 with ISA at 11.1 MHz
3Dbench = 19.6 fps
Doom = 6225 realtics, or 12.0 fps

On a slow 386, VIA 481/495 with ISA at 8.3 MHz
3Dbench = 18.5 fps
Doom = 6971 realtics, or 10.7 fps

Thus, even a slow 386-based system with DLC-33 was twice as fast as the 286-based system with SLC-33. How much of this slow down on the part of the 286 system is due to no L2 cache, and how much is due to the 16-bit data bus of the SLC?

I'm pretty sure the 16-bit data bus is the major bottleneck here. This is what I found in my testings developing FastDoom, it requires lot's of RAM bandwidth (the textures and sprites are really big, that's why having L2 cache helps a lot). A 386DX is at least 50% faster compared to a 386SX in this case.

You can't expect miracles with this upgrade. Even if you compare a proper SLC-33 on a 33MHz board with a DLC-33 (it's basically a given DLC has external cache and SLC doesn't), the SLC will have its ass handed to it. What you have is an SLC-33 that is gimped by not just 16-bit external memory, but also a crippled bus clock. In this kind of situation, you're going to want as much internal cache as possible...even clock doubling isn't going to help you.

Alright, I'll try to solder on a 5V SXLC-40 first, if L1 doesn't work, then solder the SLC2.

Catching up on this thread.

Good to hear that you got the fpu working. I feel it motivates me to take another look at the upgrade module here.

Too bad you are not able to go post 32mhz on the cpu.
And is l1 cache enabled ? I assume so, right ?

Last week I was about to look at this floppy issue bot work got in the way. Will check soon.
While memory is fuzzy about that I noticed that you were not able to get scsi going either.
100% confident scsi works on these boards since i posted about it.

I wasn't able to get SCSI working? I just tried out SCSI for the first time 3 days ago and it works just fine. I tried 1542CP and 1522B with SCSI2SD v6.

Yes, L1 is enabled and working, as is the FPU. Tested in Win3.11. It is a bit tough with only 4 MB of memory, 3712KB of which is usable due to shadowing enabled. I've had to reduce my SCSI cache size from the 4096 KB that I use on my 386 system, down to 256 KB.

I also did the native PS/2 mouse port mod with the keyboard controller DIP socket. All is good there as well. I did notice, however, that if using the 1522B, the mouse can get jumpy with lots of HDD access, which tends to happen often because of swapping and only 4 MB memory. I did NOT notice the jumpy mousse (PS/2) with the 1542CP though.

I'm using an STB ERGO PowerGraph ET4000AX card, which can only do 256 colours. I'm running it now at 800x600. I suspect 15-bit colour might be too much for a 286. If anyone knows of a ET4000AX card which can do 4096 colours at 800x600, I might try that.

Lastly, I tried using a double stacked CR2032 coin cell connected to the EXT BATT header, but when the system is powered off, it doesn't keep tick up the time. THe time shown at power on is the same as the time I last powered the system off. BIOS settings, what few there are, do get saved though. So I guess the CR2032 cannot output enough current to make the time circuit function. On the contrary, a standard 3.6 V lithium battery I have for 386 computers, that I bought way back in 2000, does keep time on this system.

Now I noticed that the EXT BATT circuit runs through two diodes, while the barrel batt. circuit runs though only one. I may pull the "charging diode" up and see if the double stacked coin cell will keep time when connected to the barrel batt. ckt. Failing that, I'll just stick with my fatty 3.6 V ext batt.

I use 3xAA lithium battery packs for everything with ext batt. Coin cells only when the board has a factory coin cell holder

Thanks for the clarifications.
At 16mhz scsi will be better than ide.
The difference in perf between the 3-4 15xx models is actuallly significant.
With 1542c being much better than the early models.
At around 20mhz scsi and ide get on par.
Past the 20mhz ide pulls ahead.
That's what I see here.

Tried briefly RAM expansion card before.
0 chance to get 25mhz or faster system with it.
Dropped the idea because of that.

Will be very interesting to see what you arrive with the CPU and RAM upgrades.

pshipkov, do you recall if this VLSI board came with a jumper on EXT BATT on 2-3 for the case with the barrel battery? From your photo of the board with barrel batt, https://www.petershipkov.com/temp/retro_pc_im … motherboard.jpg , I don't see a jumper on 2-3. Normally when using the barrel battery, aka "internal battery", one would have a jumper on 2-3.

I find it curious that pin 2 on the EXT BATT header doesn't appear to go anywhere, while pin 3 does (transistor, resistor, etc. So jumpering pin 2 to 3 would do nothing. And if that is the case, I don't see why the designers would have wired up pin 3. And if pin 2 really goes nowhere, I can see why you don't have 2-3 jumpered.

Yes, I've heard that even at 16 MHz, 0ws might not work with memory expansion cards.

Wait, there was an AHA 1522C? I thought B was the end of the line for that card.

it was a typo.
fixed it.
1542c#

never touched the battery related jumpers because i dont have external battery contraption.
the onboard battery worked well so never looked what the jumpers do or what the related wiring is.

what ram card you have over there ?

OK, sounds like a jumper on 2-3 may not be needed for use with internal battery. This is pretty weird, but so be it. I'll try the coin cell with the internal wirings of the PCB.

I don't have a RAM card, and based on what is available on eBay, I won't be buying one anytime soon.

Something just crossed my mind. Dont know why didn't think and try it before.
For cpu upgrades and extra ram it may be better to use one of the very late 286 mobos like this one, or similar.
They are not speed demons because of built-in wait states, but support up to 16mb ram and with proper cpu upgrade module I suspect we can take them very far.
There won't be much 286 left in there since even the chipset is 386 based, but can be an interesting hybrid.

Checked briefly online for ram extension cards - inventory is low, the availeble models are ok at best, prices are too high.

Yeah, even if you set aside price, there's nothing of interest on ebay right now for ram cards.

For this particular build, I want to upgrade a real 286, chipset and all. If I'm stuck with 4 MB, that's fine. Maybe some 2D GUI acceleration, DMA SCSI, CF/SD card, etc. will pickup the slack.

Same reason I am using the AMI Mark V Baby Screamer for my SXL2-66 386-to-486 upgrade, I want a genuine 386 to upgrade.

pshipkov, do you recall all of which graphics cards you were able to use on this motherboard? I've found that GD5434 and ET4000/w32i do not function.

EDIT: double-stacked CR2032 appears to be holding time properly when connected to the barrel battery circuit.

Last time I was playing around with multiple 286 boards, I was using one of these http://www.vgamuseum.info/index.php/component … ologies-f82c451 I think the GW model there. It was "sorta fast-ish" for it's age/generation and a 256kB VGA, it was faster than those big old WDC and Oak cards, and faster than the worst low revision TVGA8900 cards but not as fast as D revision. But it worked nicely on everything. I'd call it a card for 25Mhz and below though, that's about when you start to notice it's holding you back, benchmarks would probably say sooner.

@feipoa

ET4000/w32i worked fine on all 286 motherboards i touched so far.
I use the very late 2Mb model from Micro-Labs.

STB Nitro and Diamond Speedstar 64 (both CL GD-5434 based) don't work on 286 mobos.

@bitwrangler
Never tried F82C451 ISA.
Curious now.

This Diamond Speedstar 24 model is great fit for fast 286 computers.
A very late revision of the series with 24-bit RAMDAC and surface mounted components.
Earlier models utilize through-hole PCB/components.

Trident TVGA8900 revision D is also one of the best ISA VGAs.

pshipkov wrote on 2021-12-24, 01:47:

STB Nitro and Diamond Speedstar 64 (both CL GD-5434 based) don't work on 286 mobos.

I'm going to have to confirm this on my next trip. I was somewhat certain my Speedstar64 at the very least worked on my 5170 board with CPU upgrade.