z386: An Open-Source 80386 Built Around Original Microcode

Post by bitwize » Sun, May 24, 2026, 6:04 AM UTC

AviationAtom wrote: post #27

bitwize wrote: post #7

Earlier quoted context omitted.

A few years ago there was a story where the single Amiga that ran an entire US school district's HVAC was replaced with a system costing like 1.5 million dollars, after 30 years of dutiful service. I can't think of examples offhand but you bet your ass there are donut shops and auto body repair services running 386s to do POS, inventory, and the like. Some of them may be driving terminals off Xenix.

You missed a fun part of that story! The person who programmed it was a kid in the district at the time. They continued to hire him to come back and maintain it any time they had issues, which apparently was fairly rare.

Post by spankibalt » Sun, May 24, 2026, 10:47 PM UTC

nand2mario wrote: post #32

spankibalt wrote: post #29

Sadly, without an accompanying FPGA-implementation of an FPU it's much less useful for productivity work/research, i.e. outside of 08/15 gaming and application fare. Same with Ao486, which only implements a 486SX.

I think there are two reasons we haven’t seen an FPGA FPU yet, especially for MiSTer. First, FPUs are complex and FPGA support for floating point is limited. There's DSP blocks for integer additions and multiplications. But very little FP support. Second, the CPU itself may not be fast enough for an FPU to matter much. Quake wants at least a 75 MHz Pentium, while ao486-MiSTer is closer to a 486-66. So we probably nee…

Post by rasz » Mon, May 25, 2026, 7:22 PM UTC

spankibalt wrote: post #33

nand2mario wrote: post #32

Earlier quoted context omitted.

I think there are two reasons we haven’t seen an FPGA FPU yet, especially for MiSTer. First, FPUs are complex and FPGA support for floating point is limited. There's DSP blocks for integer additions and multiplications. But very little FP support. Second, the CPU itself may not be fast enough for an FPU to matter much. Quake wants at least a 75 MHz Pentium, while ao486-MiSTer is closer to a 486-66. So we probably nee…

Aye. Well, hopefully something comes to pass as a lot of industry-specific applications demand the (emulated) physical presence of an FPU. Keeping that in mind, it's obviously high-level bitching (as we say in Germany); I, as a fan of IBM PCs and compatibles, am very fascinated by your and others' awesome work in this domain.

Post by rasz » Thu, May 28, 2026, 10:07 PM UTC

spankibalt wrote: post #36

rasz wrote: post #35

Earlier quoted context omitted.

> a lot of industry-specific applications demand the (emulated) physical presence of an FPU Can you name some? I cant come up with any real world uses of FPU implemented PC for industrial use. Even MISTER is pushing it considering availability of emulation.

What I've personally seen that needed an FPU: a water analysis package for a "field laboratory" (its centerpiece being a luggable PC), several in-house applications of an insurance company (which my mentor, a mathematician, coded), as well as a bespoke, modular sasec (safety and security) suite for facility management. I'm slowly building a reference list of DOS- and UNIX-based industry software, as I have an interes…

Post by asdefghyk » Wed, Jun 03, 2026, 8:10 AM UTC

bitwize wrote: post #30

asdefghyk wrote: post #20

Earlier quoted context omitted.

RE "....a system costing like 1.5 million dollars, after 30 years of dutiful service....." I immediately wondered ... how long the new system would last or be used .... and how long it would be problem free ?

Ultimately that kind of question doesn't really matter. The only question that matters is "who will fix it when it breaks?" The Amiga system was a single machine running custom code written by one guy. If that guy dies or decides to quit maintaining it and it fails, hundreds of school kids are going to end up shivering or overheating for who knows how long. That's an unpleasant risk that may prove more costly than th…