DEC: The best of systems, the worst of systems
Digital Equipment Corp's hits and misses
Opinion Which were the greatest DEC computers and why? Which were the worst - and why?
Everyone has their own definition of greatest and worst, and exemplars of each, but I'm looking at the machines that had the most or the least influence. Since DEC under Olsen got a lot of things right, it's quicker and easier starting from the bottom.
The PDP-4, a follow up to the original PDP-1: The PDP-4 was 5/8ths the performance of the PDP-1 for half the price, and that just didn't cut it.
The Rainbow: A complete misreading of what a PC should be.
The PDP-11/60: Intended to be a reliable, maintainable mid-range PDP-11, it couldn't be maintained and was unreliable. The Rhode Island Computer Museum has in its collection nearly every flavor of PDP-11 ever made, with the notable exception of the PDP-11/60. They've never been able to find one.
The PDP-8/S, a serial implementation of the PDP-8: It was intended to be a minimal implementation of what was a minimal computer architecture. It was clever, and in a notably small package (for its day), but it was too slow to get out of its own way. It was rapidly obsoleted by IC (integrated circuit) technology.
I must also admit to not being a fan of the VAX architecture, which, to some people, is sacrilege. I like computer architectures that are simple, clean and elegant, none of which characteristics the VAX has.
I always got the impression that Gordon Bell's people never understood that, just because you can add a feature, it doesn't mean you should. Of course the VAX was wildly successful, with an army of devotees unto this day, so one can't exactly say it was among DEC's worst efforts. But it was not their best.
Don't get me started on the Alpha…
Now from the top:
The PDP-1: While clearly a "first effort" design full of things we now know could have been done better, the PDP-1 is technologically important in that it brought the idea of small, cheap, interactive computers to the world. Had there not been a PDP-1, we'd still be communicating by post with letters written on typewriters.
That you can type something into a computer and edit it in real time, display it on a screen, then send it elsewhere, is all the legacy of the PDP-1.
The PDP-7: in spite of itself. The PDP-7 was the successor to the PDP-4, and was something of a mess mechanically and thermally. (I spent four years working with a surplus PDP-7 that was held together with tape and bailing wire, so I have a particular fondness for the type.)
Unix was first implemented on a cast-off PDP-7, earning the machine a place in computer history it probably would not otherwise have deserved. PDP-7s tended to be more productive after their nominal working lives ended, when people got the chance to play with them without "adult supervision" than during them.
The PDP-10 series: For a long time everybody's first computer - via timesharing. The architecture was elegant, the tools were superb, the operating system has never been bettered, anywhere, and the things were rock solid. The PDP-10 was the pinnacle of everything that DEC got right. And then DEC murdered it in favor of the VAX.
The PDP-8/e: For the first time, all the pieces that made up a minicomputer system came together:
A workable architecture.
A powerful resident operating system (OS/8), supported by tools and compilers galore.
A rational bus (Omnibus) that allowed easy system expansion and the ability to roll-your-own custom devices.
The right packaging.
Documentation that told you *everything* and...
A rabid user group (Decus) that provided tons of free code, sort of an early open-source movement long before anybody coined the term.
The PDP-8/e was enormously successful in its day.
The PDP-11/34: In some ways the 16-bit successor to the PDP-8/e, the /34 was the right-sized machine, for the right price, for an awful lot of applications. As semiconductor technology progressed the PDP-11/34 was supplanted by the PDP-11/23; the same ideas, but for a lower price.
OK, that's my list. Ask any N retro-computing enthusiasts and you are likely to get at least N lists, all mutually incompatible. And the "discussions" that ensue when listers compare lists is most amusing - particularly when experienced from a safe distance. (Be prepared for an extended performance. Earplugs are recommended. So is a fire extinguisher.)
Before closing, let me posit a thought. My list of DEC machines is certain to be controversial, as would be anybody's list, but that's nothing. If you want to start a real column-inches-filling flame war, once the battle among DECies calms down, pose this question:
Which was better, the PDP-11 or the [Data General] Nova?
But first, make sure you're within dashing distance of your fallout shelter. ®
I'm one of those old-timers who worked on with the PDP-1 (although well after its heyday), as well as the PDP-5, PDP-6 (a 36-bit mainframe), PDP-7, PDP-8 series, PDP-9, PDP-10 series (the successors to the PDP-6), PDP-11 and PDP-12 (a combination PDP-8 and a specialized DEC computer called the LINC). I never got to work on a PDP-15, but one can't have everything.
I was the Vice President of the Rhode Island Computer Museum, and am a member of the Retro-Computing Society of Rhode Island, both of which have large collections of minicomputers. I myself have several flavours of PDP-8s, in various stages of disrepair, as well as PDP-11s, an HP-1000, and several other vintage machines.
"The" Computer History Museum on the Left Coast (as though there's only one...) gets all the retro-computing limelight, even though a lot of its collection was once in the defunct Boston Computer Museum, and the retro-computerists in New England are left shivering in the cold and dark.
Both the Rhode Island Computer Museum and the Retro-Computing Society of Rhode Island are strictly volunteer organizations that are doing what they can to preserve our technological history, and mentioning them might get them a little well-deserved publicity.
I don't know what it is about Rhode Island, but there are a lot of folks there who collect old kit. In addition to the RICM and the RCS/RI, there's also the Warbirds Museum at Quonset Point, full of old aircraft, and the New England Museum of Wireless and Steam, with two huge collections, one of pre-WWII radios (including the entire Massey Point Judith spark station, with building), the other of running stationary steam engines. Maybe it's the water or something...
Here we are mumble years after VAX clusters first appeared and still MS clustering is no where near the functionallity!
Ah, I miss working on VMS.
My 1st real job in computer operations introduced me to VAX/VMS on an 11/780
I later moved to programming and spent 20+ years on VMS systems VAX and Alpha.
The VAX architecture was for its time the best by a long way, easy to use, easy to debug, and probably still the most stable and reliable OS you can buy. There may have been some instructions that were hardly ever used, but DEC did the right thing when it came to machine checks.
Every (and I mean EVERY) instruction possible on a VAX was ether correct and verified or it was guaranteed to throw a hardware exception. This was also true of the Alpha, so unlike the early SPARC, MIPS and other processors you couldn't crash a system from user mode just by creating duff machine code.
As a result DEC were able to both add and remove instructions in later hardware and just add code to the exception handlers.
For example the MOVC3 and MOVC5 and other instructions were not in the MicroVAXs hardware, they became functions in the OS that were called when the CPU throw an exception.
Likewise the later Alpha CPUs had new instructions for accessing single bytes in memory, this improved performance of later Alphas a lot, but running that new code on older Alpha would run (slower due to the exception handling).
Likewise VMS was (and is) source code compatible with all previous versions, and image compatible within a hardware platform, so I can run a program compiled 30 years ago on an 11/780 and it would still run on the MicroVAX I have at home or a SIMH emulator today.
Somewhat different to the crap OS's we have today with Windows or this weeks release of Linux not being compatible with a year old application without a rebuild.
I'm certain anyone who truely got to know and understand VMS misses it.
Those were the days
When IT people actually understood how computers worked.
Slag the Alpha as much as you will, it was still a performance leader until poor management killed it.
Much of the architecture used today in X86-64 cpu's have DEC engineers to thank for getting them to where they are today.
Let's also not forget DEC's contribution to storage. They had pioneering work in SCSI systems and created what is today's Storageworks division in HP.
Had the company had better leadership and marketing the current lineup of vendors may have been somewhat different..
"Don't get me started on the Alpha…"
How dare you trash the Alpha. Heathen!
The Alphas might have been power hungry heat pumping beats, but they screamed performance wise. Not only were they fast, but their design was a HELL of a lot cleaner than anything Intel ever designed. They were clean, fast, and just all around awesome.
At least when buying Alpha gear from DEC, you knew you were buying a machine that could literally get the crap kicked out of it on a continual basis and not even flinch. I wish I could say that about our Sun gear!