Uncreative Labs

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I have started work on a nice little 386 machine, and am having a few minor problems. Here is what's in the system at the moment:

-4/386 hybrid motherboard with OPTi 495SX chipset (DLC support)
-256kb 15ns cache memory
-AMD 80386DX 40MHz
-Intel 80387DX 33MHz (running at 40MHz)
-32MB in 30pin RAM at 60ns
-ATi Mach 64 VLB w/2mb VRAM
-Adaptec 1542C SCSI controller
-Sound Blaster AWE64G
-16550/ECP I/O
-HP C2247 1GB SCSI-2 HD
-Sony CDU-541 SCSI-1 1X CD-ROM

The system runs pretty well for the most part, but I've been having difficulties getting the SCSI and PnP soundcard to work. In order to get through the soundcard setup I had to change the address and DMA of the SCSI controller. However, when I rebooted I was unable to access my CD-ROM drive. I think this is a pretty common problem, does anyone know how to fix it?

Also, I am having some minor issues with my VLB graphics card. Though I am running a 386 chip, I decided to risk trying VLB which is optimised for the 486 bus.It seems to work only at certain resolutions. It works in 256 colour mode at 640x480, and all 1024x768 modes. 800x600 doesn't work at all. It's really strange. Anybody out there used a VLB 386 before? I am hoping the problem will go away when I get my Cyrix chip installed.

Joined: 19 Apr 2006 Posts: 261 Location: WisConSin

I did use a VLB 386 system for a while but it wasn't a hybred unit and only clocked 25mhz (also at that time I didn't take apart computers). From what I remember being told from PCS, VLB was perfectly happy on a 386 but was very timing sensitive. You may not be able to run 40mhz and use VLB, to state the obvious check and see if there is a wait state jumper for the VLB bus on the board as that may help quirks to dissappear, other than that I can't answer further.

Good Luck

Joined: 01 Oct 2004 Posts: 169 Location: behind you!

VLB was nothing more the pins from the 486 so it ran a the bus speed. Other than for the 486DX50 most 486 processors ran at 33mhz (a few also ran at 25mhz). You might have to find the isa version of that card if you want to run faster than 33mhz. Also if you can find another motherboard give it a try.

http://www.pcguide.com/ref/mbsys/buses/types/olderVLB-c.html

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

Hmm...you say you had a 386 only system with VLB? Are you certain? Any VLB 386 board I have ever seen also has a socket for a 486. If you did have an 80386 only VLB system it was probably pretty rare. VLB is designed for 486 systems, but can also sometimes work on 386 and Pentium systems. I have a Pentium 60/66 motherboard that only has VLB and no PCI...and I know there are others like it from other companies. Though supposedly it doesn't work quite properly because of the timing issues. The same applies to 386 VLB systems. Though, aparently there are some VLB cards specifically designed with a 386 mode. I have a WD card that has a jumper to select CPU type. I am not yet sure if my Mach64 is having problems because of the 386 CPU or the 40MHz bus. Though, I have ran this card at 40MHz in other systems and it doesn't have this problem. I'll do some more testing to figure it out.

So far most of the problems I have with my 386 seem to stem from the conflict between the 1542C SCSI card and my AWE64G. I am going to slap in an AWE32 and see if that fixes it.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I upgraded to the latest copy of the Creative Labs plug n play manager. It seemed to help a little bit, but it still has problems sometimes. I think I'm just going to avoid plug n play Sound Blasters from now on. I guess I'll just downgrade to an SB16 with waveblaster add-on card.

In the meantime I've been doing some benchmarking on my 386 system. It seems to fare pretty well. The Mach64 VLB eats everything in the Wintune 2.0 database for breakfast. I running at 1024x768@64k and it pulls 2.2MP/sec. I am also getting just over 4.5MB/sec on disk access with my 1542C and HP SCSI drive with 32-bit disk and file access enabled. I think that pretty much saturates an 8MHz AT bus. I'm not sure about the memory scores. They're about 13MB/sec. I think it's above average for a 386, but I'm not certain. I need to tweak some BIOS settings perhaps. CPU and FPU are predictably right where they should be. It's a pretty fast 386. It feels more like a 486.

My Cyrix DRx2 33/66 came in the other day. Though, it doesn't have a heatsink, so I haven't been able to test it. I want to get a heatsink that I can easily remove. It's a rare chip, and I don't want to ruin it with epoxy. I'm not sure if I want to run the Cyrix in this system for very long. I already have enough 486 stuff, and I like to keep the 386 a 386. This system is pretty much done, but I need to buy a good I/O card, a new SB16, and maybe a Cyrix Fasmath.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

After tinkering around some more, I was able to solve the display difficulties with my Mach64. I just had to run the DOS config software, and now everything seems to work properly. So I guess VLB on 386 works alright afterall.

Joined: 03 Feb 2006 Posts: 488 Location: pennsylvanai

I suppose that it is almost a 386
but so are the tiny slc or blue lighhtning boards
( chips that report varoiusly as 386 or 486)
I have a forex 3/486 board. It was sold as a 386 system and after looking at it later I upgraded it to a real 486dx.

I would like to see you trying the same things on a real 386
that is a mb without the vlb- which is really a "486 thing"
and with a 386 dx and 387.

I know manufacturers try to push the envelope and make boards that offered newer tecnology while keeping older designs.
they were the ones that really bent the rules and
made hybrids. '
case in point the 386sx boards which was generally or loosely based on
26\86 concepts and sesigns.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

Quote:

I would like to see you trying the same things on a real 386

I was originally going to base my system around a 2/3rd baby AT ISA motherboard, but I had this VLB board floating around and I was really curious to see how it performed. I tend to agree that VLB doesn't have much place in a 386. It would be nice if I had a full size AT 386 board to play with. I think I also have a Mach64 ISA adapter, so maybe I should put together an ISA machine with the same hardware and benchmark under Wintune 2.0. I'll post the results when I'm done.

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I just purchased a TI486SXL-40MHz chip for this machine. Supposedly it contains an 8kb L1 cache which provides a significant performance boost over the Cyrix DLC chips. I am really curious to see how this will fair against a DRx2 33/66. Any of you guys ever tried the TI chips before?

Joined: 02 Oct 2004 Posts: 594 Location: Western NC

Yeah, had a TI 486 chip (don't remember exactly which) in an "original" Compaq 386 Deskpro. Wasn't that terribly impressed with it. Maybe it was the settings, or something else, but my old 386DX-33 seemed faster...

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I think it really depends on the chip you use.

-Not enabling the cache doesn't really do too much for performance.
-A 386SX doesn't seem to benefit as much as a 386DX
-The SLC and DLC chips aren't really meant to be direct replacements for 386 chips, and often require a new motherboard to really shine.
-Some TI chips are exact clones of the Cyrix chips, while the SXL, SXLC chips are based on modified Cyrix core. Supposedly the 8kb cache really helps.