[gumby]

That’s because Eric Ostrom had somehow gotten us a vax 750 for some inexplicable reason (years later he told me he was astonished that nobody appreciated it) as if anybody wanted a vax.

So RMS started using it for his gnu project since nobody else cared. It was just using up power in a small machine room on the 3rd (or 7th — I can’t remember) floor of tech square.

Complete happenstance.

[fl7305]

A 750 wasn't very fast back in 1987 if I remember it correctly? But a 784 was still decent?

[rahen]

Not very fast, but it was a bit of a standard in the BSD world as most development there happened on 750s at Berkeley.

https://gunkies.org/wiki/4.1_BSD

[fl7305]

Yup. My point was that I can understand if someone rejects a 750 in 1987 because it is fairly slow. I think home computers like the Amiga and Atari ST had at least that much raw CPU power?

But VAXen in general in 1987 weren't yet hopelessly slow, right?

I can understand if people didn't like VAXes for personal reasons. I had a pick of both a fast VAX and fast Sun workstations in 1987, the Suns were clear winners for me.

[gumby]

It was delivered back when the 750 was new, but we had lispms and PDP-10s and didn't care about stuff like vaxes.

I think it was already obsolete when RMS started using it, and had probably never been used over the years by anyone. Nowadays that kinds of thing is unremarkable, but back then at most places it would have been shocking.

[rahen]

Yes, it was about the speed of an original Macintosh or a turbo PC/XT, and slower than an 11/70.

https://www.tech-insider.org/unix/research/1986/0219.html

[fl7305]

Thanks, looks like the VAX 11/750 was pretty much the same Dhrystone speed as an 8 MHz 68000 (Atari ST, Amiga).

I/O and disk bandwidth is another matter of course.

[kjs3]

A 750 was a nice 'personal computer' in 1987 (I ran 3 of them in that year, along with a 780 and a bunch of different microVaxen/Vaxstations) especially if you had plenty of memory (8MB was comfy, 14MB max). CPU wasn't so fast (less than 1MIP), but I/O was well engineered and well matched so it 'felt' responsive. It was reasonably fast with 1 user, not terrible up to maybe 3-4 power users and significantly more just doing email/text processing/etc. And the CPU only weighed about 100lbs (without rack & disks)!

The 784 was more capable (with caveats), but 1) only a handful were ever built (less than 10?), and 2) it was huge, both in physical size and power consumption (it's basically 4 x 11/780s with a custom interconnect cabinet). And as I understand not terribly reliable. You might be thinking of the 785, which was an improved 780, so it was still big and power hungry, but lots more were built.

[fl7305]

> You might be thinking of the 785

Yes, I wrote that wrong. I initially checked the VAX wikipedia page and thought 784 looked familiar. But I'm pretty sure it was a 785 now that you remind me.

> I/O was well engineered and well matched so it 'felt' responsive

Yeah, I remember back then how Dhrystones were pretty misleading when comparing things like a VAX 11/780 and a barebones 68000 system.

It was interesting working on VAXes. They had really good documentation (10 shelf-feet of orange binders :), and I liked the ";n" automatic file versioning. But having a personal Sun workstation with X11 was so much nicer, and Unix felt much more natural.

[kjs3]

Dhrystones were pretty misleading

Yeah...always good for a laugh. Sure, your 68k can compute a Sieve of Eratosthenes 3 times faster than my 780 (or whatever)...but no 68k alive (at the time) could support 50+ interactive terminal users like we did all day every day (and provide email, netnews, ftp, etc. for the whole campus).

DEC VMS is indeed very nice, but we didn't run it. We ran a locally hacked version of BSD 4.2/4.3. At some point I got upgraded to a Sun 3/160 on my desk (well...next to it) so I hear you.

[fl7305]

> At some point I got upgraded to a Sun 3/160 on my desk

I was going to say that it was a nice thing to have fall into your lap, but considering that it weighed 100 kg, maybe not.

I got started with a Sun 3/50 when it was a few years old. It was slow, but surprisingly usable as an X11 development machine for C programming.

[I_am_uncreative]

It's hilarious how today we have a variant of this same argument with desktop vs. mobile CPUs.

[gumby]

No, but it had been lying around unused in a machine room, powered up, for a few years. RMS published the GNU manifesto in 83 or 84.

[fl7305]

Wasn't VAX assembly very orthogonal and nice? I can understand if it was used as a compiler target, whereas x86 strikes me as harder to deal with?

So if you have the space and free electricity in 1987, sure, give me a fast VAX.

Not so much if you live in a student dorm, but I'm sure some have done that too.

[kjs3]

Wasn't VAX assembly very orthogonal and nice?

This is the stuff of religious wars; and the VAX is the patron saint of the CISC school of ISA design. Large parts of the VAX ISA are very nice, and it's a lot of fun to program in assembler. There's (relatively for the time) lots of registers, and tons of addressing modes. But some of it is plain bonkers. How many variations of ADDL3 are there across all addressing modes? Dunno...thank gawd the doco is excellent. Then you get to things like INDEX and the numerous character string instructions and suddenly you got a migrane. You want BCD? Well of course you do. A CRC instruction? The customer is always right. Bit fields? Why wouldn't we? Didn't find something you like? We have the writable control store option so you can microcode your own instructions.

[fl7305]

Yeah, I think I remember seeing the sysops load the VAX CPU microcode using a floppy on the front panel (?)

I don't disagree in general. Writing a disassembler must have been a real challenge.

It's a waste of gates in the CPU. You put a lot of unnecessary combinatorical logic on the critical path, which limits the clock speed.

RISC chips remove everything that is not needed for the output of a C compiler, making the chip smaller and faster.

But from the perspective of Stallman writing a C compiler and having to generate and read lots of assembly code, I can see how the VAX assembly was easy to deal with. He could skip past a lot of stuff like BCD/CRC.

I'm not intimately familiar with 386 assembly, but my impression is that you have a lot of interdependencies and special cases? That can't be fun when writing a compiler. But at least it's not an accumulator-based CPU architecture like the 6502 or the PIC16, where everything has to be done through a single register.

[kjs3]

The 730 & 750 load microcode from cartridge tape (TU58). The 780/785 had a 'front end processor' (a baby PDP-11) which loaded microcode from floppies.

It's a waste of gates in the CPU.

Couple of things. First, VAX was designed when lots of stuff was still written in assembly, so they threw the kitchen sink at it. You didn't have a stdlib, you had huge numbers of assembly instructions. That wasn't how things evolved, but hindsight is 20-20, as they say. Second, C wasn't top-of-mind when designing VAX. The DEC systems programming language equivalent was BLISS, which is quite different than C. And FORTRAN & COBOL were probably more important.

And, yes, the folks who came up with RISC often cite the baroque nature of the VAX instruction set as inspiration for stripping things down. But there again, not driven by C per se; the first VLSI RISC, the IBM 801 (later PC RT), was targeted for a language called PL.8, a descendant of PL/I.