[zik]

The Bellmac-32 was pretty amazing for its time - yet I note that the article fails to mention the immense debt that it owes to the VAX-11/780 architecture, which preceded it by three years.

The VAX was a 32-bit CPU with a two stage pipeline which introduced modern demand paged virtual memory. It was also the dominant platform for C and Unix by the time the Bellmac-32 was released.

The Bellmac-32 was a 32-bit CPU with a two stage pipeline and demand paged virtual memory very like the VAX's, which ran C and Unix. It's no mystery where it was getting a lot of its inspiration. I think the article makes it sound like these features were more original than they were.

Where the Bellmac-32 was impressive is in their success in implementing the latest features in CMOS, when the VAX was languishing in the supermini world of discrete logic. Ultimately the Bellmax-32 was a step in the right direction, and the VAX line ended up adopting LSI too slowly and became obsolete.

[rst]

You might want to be more specific by what you mean by "modern", because there were certainly machines with demand-paged virtual memory before the VAX. It was introduced on the Manchester Atlas in 1962; manufacturers that shipped the feature included IBM (on the 360/67 and all but the earliest machines in the 370 line), Honeywell (6180), and, well... DEC (later PDP-10 models, preceding the VAX).

[PaulHoule]

My impression of the VAX is, regardless of whether it was absolutely first at anything, it was early to have 32-bit addresses, 32-bit registers and virtual memory as we know it. You could say machines like 68k, the 80386, SPARC, ARM and such all derived from it.

There were just a lot of them. My high school had a VAX-11/730 which was a small machine you don't hear much about today. It replaced the PDP-8 that my high school had when I was in elementary school and visiting to use that machine. Using the VAX was a lot like using a Unix machine although the OS was VMS.

In southern NH in the late 1970s through mid 1980s I saw tons of DEC minicomputers, not least because Digital was based in Massachusetts next door and was selling lots to the education market. I probably saw 10 DECs for every IBM, Prime or other mini or micro.

[rst]

In all those respects, the VAX was just following on to the IBM 360/67 and its S/370 successors -- they all had a register file of 32-bit general purpose registers which could be used to index byte-addressed virtual memory. It wasn't exactly an IBM knockoff -- there were a bunch of those, too (e.g., Amdahl's) -- but the influence is extremely clear.

[mjevans]

Period might be the best word. Contemporary is also a contender I thought of first, before disqualifying it for implying 'modern'.

[pinewurst]

Also Prime as well in the 70s pre-VAX.

[TheOtherHobbes]

The article says the Bellmac-32 was single-cycle CISC. The VAX was very CISC and very definitely not single cycle.

It would have been good to know more about why the chip failed. There's a mention of NCR, who had their own NCR/32 chips, which leaned more to emulations of the System/370. So perhaps it was orders from management and not so much a technical failure.

[kimi]

I don't think it was single-cycle, someone mentions a STRCPY instruction that would be quite hard to do single-cycle....

[Tuna-Fish]

Single-cycle doesn't mean that everything is single cycle, but that the simple basic instructions are. As a rule of thumb, if you can add two registers together in a single cycle, it's a single-cycle architecture.

[larsbrinkhoff]

> introduced modern demand paged virtual memory

Didn't Multics, Project Genie, and TENEX have demand paging long before the VAX?

[zik]

I should have said "supermini". While mainframes had tried a variety of virtual memory schemes, the VAX was the first supermini to adopt the style of demand paged flat address space virtual memory which pretty much set the style for all CPUs since then. A lot of VAX features, like the protection rings etc., were copied to the 80386 and its successors.

[vintermann]

There was also the Nord-5, which beat the VAX by another couple of years as a 32-bit minicomputer.

[Instantix]

Yeah, 1972 - "Nord-5 was Norsk Data's first 32-bit machine and was claimed to be the first 32-bit minicomputer". The Wikipedia record: https://en.wikipedia.org/wiki/Nord-5

[pinewurst]

Also Interdata with the 7/32 and 8/32.