Comment by lproven

> SCO Unix on a 25 MHz 386sx with 8 MB and another 6 MB on an add-in card

OK, SCO Xenix not SCO Unix, but I deployed production Xenix boxes with 4MB of RAM on 80386DX processors.

It ran well and supported 4-6 users no problem. As I recall, one customer had 8 users and they needed a RAM upgrade. I think, dimly now as this wasn't my department, it was eye-wateringly expensive. Something in the region of £5,000 to £6,000 (at the time, $10K+).

We did deploy one box with just 2 MB of RAM, but that didn't work well once a few users on terminals logged in. They had to upgrade the RAM.

FWIW these were 32-bit 386 machines, but with no CPU cache – the lower-end IBM PS/2 Model 80 variants of the time, with 16 MHz and 20 MHz CPUs. (The top-end 25MHz Model 70 had a small SRAM cache for the CPU. It cost over £10,000 with no screen, keyboard or mouse, and my Acorn Archimedes A310, which cost me £800, absolutely smoked it: it was about 4x as fast.)

That's when I knew Arm would eventually eat x86: in 1989. It's finally happening now.

But I was running PC DOS and DOS software in a window on my ARM desktop in 1989, in pure software emulation, and it was sluggish but usable. CPU was equivalent to a 2-2.5 MHz 8086, but disk performance was better than a screaming fast SCSI disk, so it balanced out.