You stick it into a computer and look at the BIOS info screen.

He wasnt lying 😉

http://xhoba.x86-guide.com/en/collection/ULSI … pu-no12377.html

Ampera wrote:

You stick it into a computer and look at the BIOS info screen.

I believe that the BIOS only displays if an FPU is present or not. Plus it'll run at the processor's speed if the motherboard doesn't have jumpers for asynchronous operation -mine doesn't, am i wrong on this?

vandenabeele andries wrote:

He wasnt lying 😉

http://xhoba.x86-guide.com/en/collection/ULSI … pu-no12377.html

How can you tell? This one also has "40" engraved on the chip.

Ampera wrote:

You stick it into a computer and look at the BIOS info screen.

That just reports the speed you set it at.

BitWrangler wrote:

Ampera wrote:

You stick it into a computer and look at the BIOS info screen.

That just reports the speed you set it at.

Yeah, sorry I have a massive cold so my brain is half busted.

I forgot you manually set speeds for 386 stuffs.

that chip is marked 1990. that is at the tail end of the 386 era, but before AMD made theirs (iirc). So I would deduce, because it has NO other markings regarding speed, It will likely run just fine with any INTEL 386. (up to 33mhz)

That chip is marked end of 1993, the bottom right 4 digits are year-week. 51st week of 1993.
So yeah, based on logical assumptions an FPU manufactured almost in 1994 should be a 40MHz one.
What I'm really after is a solid way of identifying this chip from its markings, without potentially wrong assumptions.

I sold mine recently and it was marked 40 on the righ side. It's only visible at an angle that sometimes doesn't show in photos.

sprcorreia wrote:

I sold mine recently and it was marked 40 on the righ side. It's only visible at an angle that sometimes doesn't show in photos.

I was late, second in line in that amibay thread 🤣 So I guess I'll just wait for it to arrive since even in your photo the speed isn't visible. Maybe it's there after all, just not visible as you said. Very helpful, thanks.

konc wrote:

That chip is marked end of 1993, the bottom right 4 digits are year-week.

I saw that, but the chip was designed in 1990. (ish) so it would be designed with chips of that year in mind. At least that is how it works in my mind.

luckybob wrote:

konc wrote:

That chip is marked end of 1993, the bottom right 4 digits are year-week.

I saw that, but the chip was designed in 1990. (ish) so it would be designed with chips of that year in mind. At least that is how it works in my mind.

In this case it is probably more about the maturity of the manufacturing process. It is likely to assume that most late chips are of a high enough quality to be 40Mhz parts and binning at that point is primarily done for market segmentation instead of actual performance binning.

luckybob wrote:

I saw that, but the chip was designed in 1990. (ish) so it would be designed with chips of that year in mind. At least that is how it works in my mind.

By that logic, Pentiums are old 1992 processors that were a year out of date in their introduction to the market. Why buy a 1992 pentium when you could buy a newer 1993 Cyrix 486-DX2 66mhz for less price at the same clock rate?

maybe i could word that differently. You can't design X, when X plugs into Y, until you know what Y is. I'd wager Intel told people (by 1990) 33mhz was as fast as they were going to make 386's. So it would make sense to design the chip to run at the correct speed as a 33mhz 386.

luckybob wrote:

maybe i could word that differently. You can't design X, when X plugs into Y, until you know what Y is. I'd wager Intel told people (by 1990) 33mhz was as fast as they were going to make 386's. So it would make sense to design the chip to run at the correct speed as a 33mhz 386.

Checkout the second photo I posted, it's a sample selection of "same" FPUs and some of them are marked as "40"

It's made during one of the final weeks of 1993. 1993 was really the last year 386s were being sold in volume, so I would almost bet on my mother's grave it's a 40MHz part. Regardless of what the marking is, if it works at 40MHz then what difference does it make?