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> Regenerating the cell layout was very costly, taking many hours on an IBM mainframe computer. I would love to know more about this – how much info is publicl

by skissane 11mo ago

> Regenerating the cell layout was very costly, taking many hours on an IBM mainframe computer. I would love to know more about this – how much info is publicly available on how Intel used mainframes to design the 386? Did they develop their own software, or use something off-the-shelf? And I'm somewhat surprised they used IBM mainframes, instead of something like a VAX.

themafia 11mo ago
There's not a lot of "off the shelf" in terms of mainframes. You're usually buying some type of contract. In that case I would expect a lot of direct support for customer created modules that took an existing software library and turned into the specific application they required.
- skissane 11mo ago
  > There's not a lot of "off the shelf" in terms of mainframes Not true-there’s still a huge amount of off-the-shelf software for IBM mainframes, and in the 1980s there was a lot more than there is now - see e.g. https://lookupmainframesoftware.com/ https://lookupmainframesoftware.com/ - in particular, the early-to-mid 1980s and earlier were really the heyday of scientific and engineering software on IBM mainframes (e.g. the original mainframe-based versions of CATIA and CADAM), before it migrated to Unix workstations. From Ken’s comment above, I know Intel was actually using Amdahl UTS, a mainframe Unix port, which is a bit of a midpoint in that transition. And of course, someone like Intel (both then and now) is going to use a lot of custom software in CPU development, whatever off-the-shelf bits they might be able to leverage.
kens 11mo ago
Various papers describe the software, although they are hard to find. My earlier blog post goes into some detail: https://www.righto.com/2024/01/intel-386-standard-cells.html https://www.righto.com/2024/01/intel-386-standard-cells.html The 386 used a placement program called Timberwolf, developed by a Berkeley grad student and a proprietary routing tool. Also see "Intel 386 Microprocessor Design and Development Oral History Panel" page 13. https://archive.computerhistory.org/resources/text/Oral_History/Intel_386_Design_and_Dev/102702019.05.01.acc.pdf https://archive.computerhistory.org/resources/text/Oral_Hist... "80386 Tapeout: Giving Birth to an Elephant" by Pat Gelsinger, Intel Technology Journal, Fall 1985, discusses how they used an Applicon system for layout and an IBM 3081 running UTS unix for chip assembly, faster than the VAX they used earlier. Timberwolf also ran on the 3081. "Design And Test of the 80386" (https://doi.org/10.1109/MDT.1987.295165 https://doi.org/10.1109/MDT.1987.295165) describes some of the custom software they used, including a proprietary RTL simulator called Microsim, the Mossim switch-level simulator, and the Espresso PLA minimizer.
- dcassett 11mo ago
  > Espresso PLA minimizer You can still find the software for Espresso (I ran it a few years ago): https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minimizer https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minim...
f1shy 11mo ago
> Did they develop their own software Knowing intel SW and based on it was succesful, I really doubt it
retrac 11mo ago
VAX were relatively small computers for the time. They grew upward in the late 80s eventually rivalling the mainframes for speed (and cost). But in the early 80s IBM's high end machines were an entire order of magnitude larger. Top of the line VAX in 1984 was the 8600 with a 12.5 MHz internal clock, doing about 2 million instructions per second. IBM 3084 from 1984 - quad SMP (four processors) at 38 MHz internal clock, about 7 million instructions per second, per processor. Though the VAX was about $50K and the mainframe about $3 million.

themafia 11mo ago

There's not a lot of "off the shelf" in terms of mainframes. You're usually buying some type of contract. In that case I would expect a lot of direct support for customer created modules that took an existing software library and turned into the specific application they required.

skissane 11mo ago
> There's not a lot of "off the shelf" in terms of mainframes Not true-there’s still a huge amount of off-the-shelf software for IBM mainframes, and in the 1980s there was a lot more than there is now - see e.g. https://lookupmainframesoftware.com/ https://lookupmainframesoftware.com/ - in particular, the early-to-mid 1980s and earlier were really the heyday of scientific and engineering software on IBM mainframes (e.g. the original mainframe-based versions of CATIA and CADAM), before it migrated to Unix workstations. From Ken’s comment above, I know Intel was actually using Amdahl UTS, a mainframe Unix port, which is a bit of a midpoint in that transition. And of course, someone like Intel (both then and now) is going to use a lot of custom software in CPU development, whatever off-the-shelf bits they might be able to leverage.

kens 11mo ago

Various papers describe the software, although they are hard to find. My earlier blog post goes into some detail: https://www.righto.com/2024/01/intel-386-standard-cells.html https://www.righto.com/2024/01/intel-386-standard-cells.html The 386 used a placement program called Timberwolf, developed by a Berkeley grad student and a proprietary routing tool. Also see "Intel 386 Microprocessor Design and Development Oral History Panel" page 13. https://archive.computerhistory.org/resources/text/Oral_History/Intel_386_Design_and_Dev/102702019.05.01.acc.pdf https://archive.computerhistory.org/resources/text/Oral_Hist... "80386 Tapeout: Giving Birth to an Elephant" by Pat Gelsinger, Intel Technology Journal, Fall 1985, discusses how they used an Applicon system for layout and an IBM 3081 running UTS unix for chip assembly, faster than the VAX they used earlier. Timberwolf also ran on the 3081. "Design And Test of the 80386" (https://doi.org/10.1109/MDT.1987.295165 https://doi.org/10.1109/MDT.1987.295165) describes some of the custom software they used, including a proprietary RTL simulator called Microsim, the Mossim switch-level simulator, and the Espresso PLA minimizer.

dcassett 11mo ago
> Espresso PLA minimizer You can still find the software for Espresso (I ran it a few years ago): https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minimizer https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minim...

f1shy 11mo ago

> Did they develop their own software Knowing intel SW and based on it was succesful, I really doubt it

retrac 11mo ago

VAX were relatively small computers for the time. They grew upward in the late 80s eventually rivalling the mainframes for speed (and cost). But in the early 80s IBM's high end machines were an entire order of magnitude larger. Top of the line VAX in 1984 was the 8600 with a 12.5 MHz internal clock, doing about 2 million instructions per second. IBM 3084 from 1984 - quad SMP (four processors) at 38 MHz internal clock, about 7 million instructions per second, per processor. Though the VAX was about $50K and the mainframe about $3 million.