AlessandroB wrote on 2023-08-25, 19:03:

i never came across IBM desktop with 386DX40Mhz processor.. does it exist? I've only seen IBM with rather slow 386SX processors and then directly 486.

Not 100% sure but isn’t a 386DX-40 an AMD chip?

Perhaps Cyrix also made one.

TrashPanda wrote on 2023-08-25, 22:17:

AlessandroB wrote on 2023-08-25, 19:03:

i never came across IBM desktop with 386DX40Mhz processor.. does it exist? I've only seen IBM with rather slow 386SX processors and then directly 486.

Not 100% sure but isn’t a 386DX-40 an AMD chip?

Perhaps Cyrix also made one.

yes intel stop at 33mhz

I'm only aware of 20 and 25 MHz from IBM. They have the same pin configuration as AMD/Intel but are in a package that has a metal casing with resin encapsulation. I'll see if I can find those I have and post a photo. They have IBM part numbers (they don't say 386 or the speed rating on the packages).

IBM computers also used Intel CPUs, not sure about AMD. Only AMD went up to 40 MHz with a true 386.

IBM kinda went a different way, they had an intel 486 license, they had cyrix licenses, and sorta bodged the two together and came out with the 486SLC series when AMD came out with the DX40... Now those ran on 386 boards/chipsets, but weren't very "drop in" on older boards due to needing lower voltage. There were upgrade boards. However, the real deal 486 was the "pro" level processor and they built systems with that, and the SLC and BlueLightning chips were in budget models, some got an IBM moniker like PS/1 and Aptiva series, some got into "arms length" this isn't really us, but actually it's us, clones called Ambra, then also IBM Microelectronics furnished boards with installed CPU to systems integrators. Their deal with Intel was that they couldn't sell CPUs with intel tech in separately from boards. So the SLC2/3/BL had intel 386 IP and probably 486IP to bolt the 486 instructions on the side of the 386ish core, and they were sold in systems or on boards only, or as upgrade modules boards/interposers through Kingston. Whereas later wholly Cyrix designs made and branded by IBM hit the market as single CPUs, though that was often a bit gray marketty and no "retail" packaged ones seemed to be around.

BitWrangler wrote on 2023-08-26, 03:51:

IBM kinda went a different way, they had an intel 486 license, they had cyrix licenses, and sorta bodged the two together and came out with the 486SLC series when AMD came out with the DX40... Now those ran on 386 boards/chipsets, but weren't very "drop in" on older boards due to needing lower voltage. There were upgrade boards. However, the real deal 486 was the "pro" level processor and they built systems with that, and the SLC and BlueLightning chips were in budget models, some got an IBM moniker like PS/1 and Aptiva series, some got into "arms length" this isn't really us, but actually it's us, clones called Ambra, then also IBM Microelectronics furnished boards with installed CPU to systems integrators. Their deal with Intel was that they couldn't sell CPUs with intel tech in separately from boards. So the SLC2/3/BL had intel 386 IP and probably 486IP to bolt the 486 instructions on the side of the 386ish core, and they were sold in systems or on boards only, or as upgrade modules boards/interposers through Kingston. Whereas later wholly Cyrix designs made and branded by IBM hit the market as single CPUs, though that was often a bit gray marketty and no "retail" packaged ones seemed to be around.

None of them are 386DX though, which is what the OP asked about.

It almost seems that IBM wanted to switch from the 386 to the 486 as soon as possible by making the switch before the 386s were offered at their maximum speed and relegating the 386 file to budget computers with the SX chips. Yet the period in which the 386 was the fastest cpu I think lasted at least 2/3 years. Even only 386 DX at 20 and 25 Mhz have been proposed, to then move on to the 486, the idea that comes to mind is that intel has proposed the 386DX33 at the same time as the 486DX33 and that IBM has chosen the 486 line for its ps/2. So in reality, in addition to the AMD DX40, the intel DX33 is also missing. If for the DX40 I can find the reason that the 486 was already on the market and that IBM wanted to choose the best (486) due to the lack of the i386DX33, I have only hypotheses.

Yep, that's what I'm saying, there isn't a DX40 sized hole because next architecture had taken over. Like there isn't a DX5-133 hole in many other PC makers lines, because they are already offering Pentiums