I think you can use it. That empty socket probably is for a 486DLC, but maybe it can be used for a co-processor. If you want to make sure it works that way, check for any jumpers indicating something fpu or 387, and also check the bios setup for any options.

edit : Now that I watch it again, I'm thinking that this socket might be just for a co-proccessor, and maybe it's designed for both weitek and other fpus like yours.

Yes thats a standard EMC socket. It works.
The remaining pins are for FPUs like Weitek Abacus and not used by a usual 387 FPU.
Just make sure the orientation is correct.

I would like to refer you to this page: 386DX40 build

at least two members here(myself included) have built a 386-40 system and the 2nd picture shows EXACTLY how math co-processors fit into the socket. take care inserting the co-pro into the socket. If nothing else, insert it and take a picture and show us, BEFORE powering up and most everyone should be able to say if it is correct.

Once you get it all setup. you MUST benchmark it!!!! We tend to use 2 benchmarks:

3dbench:
3DBENCH CPU Benchmark Database

And speedsys. ( search for it, i dont have a nice link)

CPU score in Speedsys is a bit questionable since it gets lower if a FPU is present.
A splitted score for CPU and FPU would be much better.

How many games were there that made use of a NPU? 😀

I would like to refer you to this page: 386DX40 build

at least two members here(myself included) have built a 386-40 system and the 2nd picture shows EXACTLY how math co-processors fit into the socket. take care inserting the co-pro into the socket. If nothing else, insert it and take a picture and show us, BEFORE powering up and most everyone should be able to say if it is correct.

Once you get it all setup. you MUST benchmark it!!!! We tend to use 2 benchmarks:

First, thanks to all people

I bought on ebay 32mb ram in 30pin SIMM, a ET4000AX 1mb ISA, and a ISA SCSI card + 8GB HDD

When RAM, scsi, and video arrive, i will take pictures of mobo + FPU and do all benchmarks

For sure in less than a week, all the components arrive, and I can assemble the 386 😁

THANKS!!!

h-a-l-9000 wrote:

How many games were there that made use of a NPU? 😀

There's 4 that I know of:

Simcity original, Falcon 3.0, Scorched Earth and SPISPOPD (at least, I used to have a version that complained if a maths copro was missing).

So yeah not a huge list. I ended up removing mine since it wasn't really doing much.

TFX also makes use of a floating point unit in the same way as Falcon - to determine which flight model to use.

The setup routine does a floating point test in order to choose the most appropriate mode. Might it be worth using just the TFX setup programme in order to do another set of FPU benchmark comparisons?

edit: Just checked and config.exe from TFX will run independently of the TFX install directory, so it might be another tool to do speed tests (eg video and cpu/fpu speed).

swap file is best turned off ?
it was a dos game ?

Your Dosbox has some completely unrealistic speed 😉.

Davros wrote:

swap file is best turned off ?
it was a dos game ?

Yes. TFX is a dos game. It reccomended the use of a disk based swap file (which it created) if you didn't have a certain amount of memory. Any more than 8Mb or so and it doesn't appear to need to use it.

elianda wrote:

Your Dosbox has some completely unrealistic speed 😉.

Hmm... it's a standard 0.74 build from source. Core is set to auto, cycles to around 10000 and it was built with the following parameters:

CFLAGS=-mtune=core2 -march=core2 -msse3 -O2 -malign-double -mfpmath=sse -ffast-math -fomit-frame-pointer -pipe
./configure --enable-core-inline

file /usr/local/bin/dosbox
/usr/local/bin/dosbox: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not stripped

Please note the smilie.
My screen is from a real 386DX-40 whereas benches within Dosbox are not very useful for comparison. The FPU is an Intel 387DX.
There are some drawbacks I noticed with the config.exe from TFX. It requires a mouse driver and somehow corrupts the A20 gate line on the 386 system where I tested it. (Hard Reset fixes this again). The effect is that on warmboot himem.sys is no longer able to control the A20 line.

there may be a setting in the bios for fast a20 gate handler try changing it or try another keyboard

elianda wrote:

Please note the smilie.
My screen is from a real 386DX-40 whereas benches within Dosbox are not very useful for comparison. The FPU is an Intel 387DX.
There are some drawbacks I noticed with the config.exe from TFX. It requires a mouse driver and somehow corrupts the A20 gate line on the 386 system where I tested it. (Hard Reset fixes this again). The effect is that on warmboot himem.sys is no longer able to control the A20 line.

Of course, I wouldn't think doing any benchmarks in dosbox would be very productive - I just didn't have any real dos machines to hand.

Davros wrote:

there may be a setting in the bios for fast a20 gate handler try changing it or try another keyboard

I already tried this and it has no influence. Only Hardreset seems to fix this.
And somehow the config program never detects any soundcard.

Hello, sorry for delay to answer

Here i have some photos if my 386 motherbard, and the cyrix 387

Can you help me to find the correct way to put the 387? i don´t sure

Another thing, the mainboard don´t have the battery. Any 3V battery is ok to use?

Thanks!!

I think you've placed it correctly. Watch for any jumpers for the coprocessor. Some boards may not function as they should when they're not adjusted properly.

Thank you markk, i confirm i placed it correctly.

Now i have a 387 powered beast 😉 thanks