BitWrangler wrote on 2024-09-03, 13:59:

There has been some new ULSI 3c87 FPU going for reasonable money on fleabay. If you benchmark those on science and actual mathematics oriented benchmarks, they only perform in the top half, but if you benchmark them in games, they do well, even being best in some instances (It's that whole optimizing common instructions at the expense of less commonly used instructions thing). However, most of the '92 up games that can use an FPU still play very very slowly on a 386, so it's only for bragging rights, realistically, even DX2/66 are too slow to have a smooth experience on those games.

Do you know what games are those?

I only know of Falcon 3.0 that uses FPU. But it should work fine on a 386-33 with 387 not to mention 486DX2-66.

kixs wrote on 2024-09-04, 07:11:

BitWrangler wrote on 2024-09-03, 13:59:

There has been some new ULSI 3c87 FPU going for reasonable money on fleabay. If you benchmark those on science and actual mathematics oriented benchmarks, they only perform in the top half, but if you benchmark them in games, they do well, even being best in some instances (It's that whole optimizing common instructions at the expense of less commonly used instructions thing). However, most of the '92 up games that can use an FPU still play very very slowly on a 386, so it's only for bragging rights, realistically, even DX2/66 are too slow to have a smooth experience on those games.

Do you know what games are those?

I only know of Falcon 3.0 that uses FPU. But it should work fine on a 386-33 with 387 not to mention 486DX2-66.

Falcon 3.0 was 1991, but I might as well have said from 95 up, since that's when the ball really started rolling, Duke Nukem 3D doesn't strictly need an FPU to launch, but has crippling slowdowns when any slopes come into view if you don't have one. Then Quake and quake engine games require it, and then many more games start to need it, though they probably just specify Pentium minimum by then and don't call it out.

Although ppl who have used FPU on Falcon 3.0 report that it doesn't "work fine" so much, it only comes into play in high accuracy flight mode which is reported to have a number of glitches.

Sim City often gets mentioned, but the only advantage that has been documented is that time acceleration can work faster.

Moraffware's Entrap can use x87 to speed up playfield generation, likewise Links 386 is reported to speed up environment generation with an x87, but no change in actual gameplay.

When it was only required to shuffle pixels accurately enough to look good on 320x240 or even 640x480 integer math was very much faster, floating point math was horrendously slow, and FPUs made it better than horrendously slow, but still didn't bring it up to the speed of integer math, so FPU was mostly irrelevant to gaming performance for many years.

I know, but we're talking about 386&387 that were great to have in the 1992/93. I had 286-16 that time. I also enjoyed flight sims and played Falcon 3.0 on that machine. Later I also purchased a 287 that speed it up noticeably. I needed FPU as I used ACAD10 for school.

I'm just about to start a project of rebuilding my first 286 as I've finally got all the parts and go though my early PC experiences. That weren't great having a 286 in 1992 of course 🤣

They say Scorched Earth uses the FPU as well. Since a few days I know by coincidence that it runs smooth and fast on a 286 12.5 MHz + i80287XL. And I'm planning to do a short video if there is indeed a difference noticable with/without the FPU installed.

Jackhead wrote on 2024-09-04, 06:57:

i think its not isa, its for a ram expansion board.
Putting in the voltage blaster is maybe not a good idea 😀

That's a fair point, if it's not part of the ISA bus you don't want to do that.

Still, it seems unusual given it looks like a standard 8-bit ISA slot. I'd be tempted to trace the pins and see where they are connected to.

I was vaguely wondering if it was for those "slot 8" weirdy cards from the XT days, but that's probably a wild goose chasing a red herring down a deep rabbithole or something.

That slot had me curious, so I did some digging on Retroweb and found another similar ASUS motherboard with the same offset slot: https://theretroweb.com/motherboards/s/asus-isa-486s

Per the documentation, that slot is listed as being for a 32-bit memory card.

Unfortunately, I can't find any documentation on what such a card would have looked like. It would be neat to find out what it does.

edited:

I did find another ASUS board that has a picture of a memory expansion card, albeit with a pair of sockets as opposed to just the one: https://theretroweb.com/motherboards/s/asus-isa-486c

oh that memory card has also extra cache?

Still need a nice 386 case but first test looks good. Installed 16MB Ram. A bit overkill for a 386. But i had that kit around for some years, so yes why not..
Board take the 4MB sticks without problem.
Waiting for the adaptec controller, than write some bios chips for it, install a floppy and than Dos 5.0 .

Thats what I have a AMD dx 386@40mhz CPU and an Intel 387 Mathco processor.
Works great together.
i have the jumpers on motherboard set for 33mhz so I don’t know if the 33mhz Mathco processor will work with the CPU jumpers set for 40mhz. Never tried it but it should work also.
But it still plays DOS games fine a 33mhz. And everything works fine.

Got the Adaptec in. Flashed the V2.11 bios to some new chips.
Now when it comes to I/O my plan of the address config was :
220 = CT1600
230 = Adaptec scsi (for floppy and cd drive)
300 = XTIDE (CF 4gb)
330 = Midi LAPC-I

also found this strange case here:

That's a really unique case, haven't seen one like that before. Man, I'd have a really annoying voice in my head if I owned one of those "Put an LCD in it, put an LCD in it, PUT AN LCD IN IT...." would be on repeat 🤣

BitWrangler wrote on 2024-09-05, 13:29:

That's a really unique case, haven't seen one like that before. Man, I'd have a really annoying voice in my head if I owned one of those "Put an LCD in it, put an LCD in it, PUT AN LCD IN IT...." would be on repeat 🤣

Same here 😀 haha. I just bought it online, so have to wait. Maybe its just a faceplate where you can put notes behind.

That is a fascinating looking case! I wonder what it was being used for with that timezone (?) map on it?

Could easily be a time zone map, since it has a clock ...

Intel486dx33 wrote on 2024-09-05, 12:02:

Thats what I have a AMD dx 386@40mhz CPU and an Intel 387 Mathco processor. Works great together. i have the jumpers on motherbo […]
Show full quote

Thats what I have a AMD dx 386@40mhz CPU and an Intel 387 Mathco processor.
Works great together.
i have the jumpers on motherboard set for 33mhz so I don’t know if the 33mhz Mathco processor will work with the CPU jumpers set for 40mhz. Never tried it but it should work also.
But it still plays DOS games fine a 33mhz. And everything works fine.

Your have a 386SX. 386DX is a bit different and faster.

Tests went good so far! Installed all cards with fresh dos 6.22.
I still need a ET4000ax. But for the rest anything working fine.

ISA slots:

1: voltage Blaster
2: GPU
3: Adaptec 1542cf (floppy, cd)
4: XTIDE (CF)
5: I/O for mouse (COM1)
6: ct 1600
7: LAPC-I

Also got my 387.

Here the first bench. I notice there is no L2 Cache. but i enabled it in the bios???

Jackhead wrote on 2024-09-06, 11:41:

Here the first bench. I notice there is no L2 Cache. but i enabled it in the bios???

The 386 CPU has no internal cache, so the external 64KB installed on the motherboard show up as L1.

Getting near to finish my 386:

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