386/40 - Fun, Frustration, & Taking It To The Next Level

 One of the computers I wanted to add to my retro computing collection was a 386. My initial plan was to find a period correct case and then just build it out from there. I made a post on the Vintage Computer Forum asking for such a case. A forum member, who is a recycler, reached out to me he may have what I was looking for. It turns out he had complete systems. I picked the one I liked which he told me that one was a 386. To my surprise when I got it was a 386/40 in nearly perfect condition. I upgraded the memory to 8MB, added a Cyrix FasMath math coprocessor,  XT-IDE CompactFlash adapter, Tseng Labs ET4000AX video card, Sound Blaster 16 sound card and 3Com 3C509B network card. I replaced the AMD 386/40 CPU with Cyrix 486DLC/40 CPU.

I thought I was all set, but then problems began to set in. I could not get any protected mode games like Doom to run. They would just start up and then quit. I could not load an extended memory manager like EMM386 or QEMM386. I would get protection faults. I put the 386/40 CPU back in and that helped some, but the problems continued. I ran memory tests with CheckIt 3.0 and came up Ok. Trying to run the System Board test with freeze on the protected mode tests. I was beginning to the think the board was not in working order. I switched some the memory around and when running the System Board test, I finally got through it, but it reported parity errors. It turned out the 30-pin SIMMs I was using are not all that compatible with 386 motherboards. I decided to replace the 3 chip 30-pin SIMMs with 9 chip 30-pin SIMMs as these are more compatible. That fixed the problem, and I could now run protect mode games and utilities again. I put the 486DLC/40 chip back in and problems started happening again. I ran diagnostics and it turns out that something was going on with the built in 1K L1 cache on the CPU. Disabling the 1K L1 cache fixed any issues, but that would slow the computer down to almost the same speed as when I had the 386/40 CPU installed. Now these Cyrix 486DLC chips are known to have cache coherency issues with a lot of 386 motherboards, but this motherboard had 486DLC marked on the CPU socket and recognized the CPU properly on the BIOS post screen. I tried enabling the 1K L1 cache using the Cyrix utility instead of doing this in the BIOS, as this is supposed to be more compatible. This did not help. I decided to take a chance and get a different 486DLC/40 CPU. This one worked and I have had no further issues. This finally ended weeks of frustration.

The Cyrix 486DLC CPU takes a 386 system to about as fast as you can go. How much faster? Here some benchmarks from Phil’s Computer Lab showing the results:


You will not get a doubling of performance, but I got a nice performance boost that matches the above results. For a more in depth look at this CPU upgrade, here are links to Phil’s Computer Lab and Ancient Electronics on this topic:

https://www.philscomputerlab.com/cyrix-486dlc.html

https://ancientelectronics.wordpress.com/2016/08/04/upgrading-the-386-enter-the-cyrix-486dlc/

I am really enjoying this computer. It brings back so many memories of having a 386 and what that time in computing history was like. Lastly here a few pictures of my 386/40 computer.




Comments

Post a Comment

Popular posts from this blog

The Little Known Epson Equity Ie - An IBM PS2 Model 30 Clone

Image
I have always had a fascination with 8086 XT class computers. Mainly because there were so few of them compared to the multitude of 8088 XT class computers out there. I own a Tandy 1000 SL with an 8MHz 8086 CPU (upgraded to an NEC V30). This is much faster than my Tandy 1000 SX with a 7.16MHz 8088 CPU (upgraded to a NEC V20). I have always wanted a 10MHz 8086 based system. These are as fast as you can officially go with an 8086. Intel only made them to run up to 10MHz. I had been keeping my eyes open for quite some time when an Epson Equity Ie came up for sale on eBay. The computer was in excellent condition and I ended up buying it. This is the only computer I know of outside of IBM’s PS2 Model 25 & 30 that have MCGA graphics onboard. This is basically a cut down version of IBM’s VGA chip. It only has 64K of ram vs 256K for the VGA. It supports the 320x200 256 color mode of the VGA as well as 640x480 2 color mode, but none of the VGA’s 16 color modes. This makes it pretty useless
Read more

Turning A $20 Craigslist Purchase Into A 500MHz Gaming Powerhouse

Image
Last year I picked up a couple of computers as part of a Craigslist purchase from a local seller. One the computers cost $20 and was described by the seller as "nothing special". It had a PC Chips M572 motherboard with an i430TX chipset, Pentium 133MHz CPU, 40MB of ram, 40GB hard drive, 1.44MB 3.5 floppy drive, DVD drive, 8MB ATI RageXL PCI video card and a low end Ensoniq PCI sound card. I was originally going  to take the motherboard out, but there was something about that motherboard that I remembered it could be upgraded with a much better CPU. I checked online and there was indeed a patched BIOS available to allow for the use of a K6-2+ or K6-III+ CPU. I download the patched BIOS and applied the BIOS update to the motherboard. The M572 motherboard has PnP CPU setup in the BIOS. There are no jumpers to set. This makes for easy changes to the motherboard. You can set the voltage from 2.0 to 3.5 volts, FSB speed of 60, 66, 75, or 83 MHz and CPU multiplier of 1.5 to 5.5. I
Read more