MB model was not said.

BSA Starfire wrote:

seems pretty quick for a SX 25(I had a SX 40 system in 1994)

Speed Test

here you go, first time I saw that benchmark.
as to the motherboard model, you know as much as me by looking at the pictures, all i know is IBM 1992.
Best,
Chris

BSA Starfire wrote:

first time I saw that benchmark

One of those which shows correlation with Doom. 😀 I run it by: speedtst >result.txt
Your CPU has standard for SX 25 speed there, if to approximate from SX 33.

as to the motherboard model, you know as much as me by looking at the pictures, all i know is IBM 1992

There are characters in left-upper corner near copyright. May be something useful to identify.

Thats about the best I can get out of my old IPhone 3GS.

Seems there someone has similar model. Maybe he knows the origin.

some hints
http://www.dannychesnut.com/Recording/Compute … Motherboard.htm

Looks a lot like the board from my ValuePoint... Maybe that is where it came from. Planning on dragging mine out later, so I'll have to take a look at it now. One difference I do remember though, mine has a small heatsink which looks like a stack of metal discs.

As for your FPU, any 387SX FPU should work. You can use an FPU rated for a higher clock, but not one rated for a lower clock - I use a 33MHz IIT 3C87SX with a 386SX-16 without any problems, the FPU just runs at 16MHz and does what it is supposed to and the lower clock might actually be good for it in some way because it isn't working as hard.

Cheers buddy, I'll buy that 387 from the ukraine then.

Here are the innards of my ValuePoint 325T/S with the floppy and bone removed;

Guess your board is a different revision, but for the most part it looks near identical and is the same spec. My CPU gets hotter than hell so you might want to glue on a little heatsink just to be safe.

There were once a lot of these systems in circulation, at least locally, because a large company used them until at least the late-mid-90s;

🤣, COMET, no idea! 😉
Cheers chap, my board actually came from Slovenia via Amibay.
Only run my board outside a case so far, but will figure out cooling once I build case. Bought the ULSI 387, it was only a tenner so why not.

No worries, I was going to mess with this thing today anyway. I have some more info which might be useful, or not, but whatever, here it is just in case;

J12: Near the speaker - If you take the jumper off the two pins, you should be able to use a standard PC Speaker on that jumper. The two jumpered pins redirect the signal to that metal buzzer next to it on the board.
J13: Close to J12 but around the corner - LEDs, should have an asterisk next to it to indicate Pin 1, should be the side nearest that capacitor (C7) - the pinout should be 1-2; Power LED. 3-4 HDD LED. Pins 1 and are positive, the two center pins are ground.

Oddly, my board has eight M5M44900 chips in that corner where yours has four. Not sure of their purpose, look like Dynamic RAM so perhaps the board has onboard RAM. I would test, but I daren't play with that single module I have because the board doesn't play nice with any of the modules I have spare.

Cheers again chap,
yep my board has 2MB onboard & I am using a single 8mb simm unlike the above pics for a total of 10mb.
VERY useful info on the pin outputs, thanks 😀

BSA Starfire wrote:

🤣, COMET, no idea! 😉
Cheers chap, my board actually came from Slovenia via Amibay.
Only run my board outside a case so far, but will figure out cooling once I build case. Bought the ULSI 387, it was only a tenner so why not.

I'm also using a 25MHz ULSI with my Intel 386SX-16, so I would expect it to work without a problem for you, too. Cooling is also a none issue. 386SX chips are just like that, they will blister your finger if you touch them long enough, but will continue to work none the less. Mine is still working since 1992, the first 3-4 years of its life was full of numerical analysis with FORTRAN, running programs some times taking days to complete, and still kicking.

From CPU-World:
Minimum/Maximum operating temperature : 0°C - 100°C
Typical/Maximum power dissipation : 0.75 Watt / 1.21 Watt

http://www.cpu-world.com/CPUs/80386/Intel-NG80386SX-16.html

You're probably right. Somehow I overlooked that the CPUs were the one major difference on the board - the SLC-25 mine has dissipates more than double the power of the SX-16 (About 2.5 Watts) and also significantly more than BSA's SX-25 (1.54W). I wonder what they did to it, because it doesn't really feel any faster than a normal 386SX, though I cannot enable the 8KB cache in the BIOS and that may be a factor, ugh, IBM. Power Management and the onboard cache wouldn't output that much more heat though, surely? Either way, my mind just thought that if IBM had specified a heatsink for mine, they might have for that one. But I guess not.

The 486DLC runs hotter anyway, and I had that going without a heatsink for long enough until it bothered me, now has an old northbridge heatsink glued to it.

tayyare wrote:

I'm also using a 25MHx ULSI with my Intel 386SX-16, so I would expect it to work without a problem for you, too. Cooling is also […]
Show full quote

BSA Starfire wrote:

🤣, COMET, no idea! 😉
Cheers chap, my board actually came from Slovenia via Amibay.
Only run my board outside a case so far, but will figure out cooling once I build case. Bought the ULSI 387, it was only a tenner so why not.

I'm also using a 25MHx ULSI with my Intel 386SX-16, so I would expect it to work without a problem for you, too. Cooling is also a none issue. 386SX chips are just like that, they will blister your finger if you touch them long enough, but will continue to work none the less. Mine is still working since 1992, the first 3-4 years of its life was full of numerical analysis with FORTRAN, running programs some times taking days to complete, and still kicking.

From CPU-World:
Minimum/Maximum operating temperature : 0°C - 100°C
Typical/Maximum power dissipation : 0.75 Watt / 1.21 Watt

http://www.cpu-world.com/CPUs/80386/Intel-NG80386SX-16.html

Thats good to know about the ULSI FPU, thanks 😀

1.54Watts!!!! Seems incredible compared to modern CPU's or even those from 15 years ago doesn't it??

Up and running with the 386 and a incredibly ancient Conner CP 3501 500Mb drive from late 1991, was a massive & expensive drive for the time, big old noisy double height 3.5inch drive!! Sounds like it's going to explode at any moment! I kinda love these old old drives though that you can actually hear reading and writing the data. I must get an old stepper IDE Seagate at some point.
Having lots of fun with this build so far, not sure at all yet what I will finally so to build a case though.
Best,
Chris

Sounds like it'd be a good drive to record the sound of. I love hardware that sounds like it is ready to lift off.

First 386 motherboard here too, Unichip(?), with a soldered Am386DX40 and a corroded battery. Got it to boot up with a Trident ISA VGA but gives me the dreaded keyboard error, so currently fooling around with a multimeter trying to fix it. Will post pics as soon as I get it up and running!

You asked about FPUs?

EVERYTHING YOU ALWAYS WANTED TO KNOW ABOUT MATH COPROCESSORS

elianda wrote:

You asked about FPUs?

EVERYTHING YOU ALWAYS WANTED TO KNOW ABOUT MATH COPROCESSORS

Why? Why have you done this to me????? Is midnight, I need to go to sleep but must... read... article...