Ahoy, DECmate II! the little PDP-8 that could

In 1982, as we mentioned at length with our history of the DEC Professional, Digital Equipment Corporation attempted to keep their PDP-11 minicomputer market-relevant by turning the venerable architecture into a largely incompatible desktop microcomputer. But that wasn't the only PDP-series mini it happened to, and it wasn't even the first: the PDP-8 actually got the shrink-ray treatment several years before, and not content to merely make it into a smaller general purpose computer, DEC turned it into a word processor.

Thus emerged the DECmates, descended from the 1977 DECstation VT78; arguably the zenith of the line was this one, the DECmate II, which rolled off the assembly line in 1982 simultaneously with the first DEC Professional models and the DEC Rainbow. Advertised aggressively to offices new to computers, take the two floppy disk drives built-in, add a printer, monitor and keyboard, and right away you had a simple office system for basic needs. With a Z80 or an 8086 processor card, you could turn it into an overgrown CP/M machine or a rather limited MS-DOS one. You could stick two more floppy drives in it. You could even add a hard disk or a graphics card, as long as you didn't consider what more powerful system you could have gotten instead for that money.

Now, that's a lot of word processing. But under the hood it's still at least PDP-8 adjacent, even considering its oddities and incompatibilities, and you can make it do many of the things a full-size Eight can. We'll take this basic unit, convert the floppy drives to solid state, tap the video output, and put it through its paces. After all, if we have a PDP-11 on our desk, we should really have a PDP-8 too.

Refurb weekend double header: Alpha Micro AM-1000E and AM-1200

I've mentioned previously my great affection for Alpha Microsystems hardware, which are rather obscure computers nowadays, but back in the 1980s and 1990s were fairly sophisticated 68000-based multiuser systems that turned up in all kinds of vertical markets. For example, my first Alpha Micro (an Eagle 300) came from a party supplies store, my Eagle 450 was in a 9-1-1 emergency dispatch centre, and I've seen or heard of them running in medical and veterinary offices, churches, and even funeral homes. In fact, I know for a fact many of these blue-collar computers are still out there quietly doing their jobs in back offices and small businesses to this day. They're probably most technically notable for AMOS, their highly efficient real-memory preemptively multitasked operating system, and the fact they are (as far as I can tell) the only 68K-based machines to effectively run little-endian.

Sadly my beloved Eagle 300 appears to have suffered a system board fault and will not complete the power-on sequence, so the ColdFire-based Eagle 450 has temporarily taken over server duties for it on ampm.floodgap.com. Fortunately I have a source identified for E300 replacement hardware and one or both of these systems might turn up in a future article. Until then, in our continuing household computer inventory, we have two, count 'em, two additional and earlier Alpha Micro machines we need to disposition as well: a 1982 Alpha Micro 1000 (specifically the AM-1000E, originally sold with a 30MB hard disk) and its bigger brother, a 1987 Alpha Micro 1200 (as a AM-1200XP, with additional serial ports and a 70MB disk).

The AM-1000 family were probably the most widespread Alpha Micros, at least to the extent any Alpha Micro ever was widespread, and their flexible form factor meant I knew nearly as many people who used them as desktop workstations as who used them as office servers. Neither one is booting, and if they're junk they're too big together to stay in the house. If we can get them back into AMOS, we'll find them something to do. If we can't, we'll recover the space and send them to storage. In this Refurb Weekend we'll tear them apart, find some surprises, dig a couple more out from storage for comparison, and even throw one of their hard disks into the freezer and actually get data off it ...

... but first, a little history, and then a funny story that should be past the statute of limitations about how I broke into the church database as a teenager. And, yeah, it involves an Alpha Micro.

Let's give PRO/VENIX a barely adequate, pre-C89 TCP/IP stack (featuring Slirp-CK)

I had this grand idea many moons ago about writing up a TCP/IP stack for the Commodore 64, along with a lot of other people, and several of those people eventually did so before I even wrote a single opcode of 6502 assembly. For that purpose I had bought the box set of TCP/IP Illustrated (what would now be called the first edition prior to the 2011 update) for a hundred-odd bucks on sale which has now sat on my bookshelf, encased in its original shrinkwrap, for at least twenty years. It would be fun to put up the 4.4BSD data structures poster it came with but that would require opening it.

Fortunately, today we have AI we have many more excellent and comprehensive documents on the subject, and more importantly, we've recently brought back up an oddball platform that doesn't have networking either: our DEC Professional 380 running the System V-based PRO/VENIX V2.0, which you met a couple articles back. The DEC Professionals are a notoriously incompatible member of the PDP-11 family and, short of DECnet (DECNA) support in its unique Professional Operating System, there's officially no other way you can get one on a network — let alone the modern Internet. Are we going to let that stop us?

Of course not! Here's our barebones network stack for PRO/VENIX, the Pro's only official Unix option, downloading the Google home page on real hardware (internal addresses bleeped out) over SLIP and a Crypto Ancienne proxy for TLS 1.3. And, as we'll discuss, if you can get this thing on the network, you can get almost anything on the network! Easily portable and painfully verbose source code is included.

More pro for the DEC Professional 380 (featuring PRO/VENIX)

In computing the DEC PDP-11 is something of a geologic feature. Plus, as most systems in the family were minicomputers, they had the whole monolith thing going for them too (minus murderous apes and sucking astronauts into hyperspace). Its fame is even more notable given that Digital Equipment Corporation was among the last major computer companies to introduce a 16-bit mini architecture, beaten by the IBM 1130 (1965), HP 2116A (1966), TI-960 (1969) and Data General Nova (1969) — itself a renegade offshoot of the "PDP-X" project which DEC president Ken Olsen didn't support and even cancelled in 1968 — leaving DEC to bring up the rear with the PDP-11/20 in 1970.

So it shouldn't be a surprise that DEC, admittedly like many fellow mini makers, was similarly retrograde when it officially entered the personal computer market in 1982. At least on paper the DEC Rainbow was reasonable enough: CP/M was still a thing and MS-DOS was just newly a thing, so Digital put an 8088 and a Z80 inside so it could run both. On the other hand, the DECmate II, ostensibly part of the venerable PDP-8 family, was mostly treated as a word processor and office machine; its operating system was somewhat crippled and various bugs hampered compatibility with earlier software. You could put a Z80 or an 8086 in it and run CP/M and MS-DOS (more or less), but it wasn't a PC, and its practical utility as a micro-PDP didn't fully match the promise.

However, what DEC did to the PDP-11 was odder still. The 1982 DEC Professional 350 had the same F-11 ("Fonz") CPU as the bigger PDP-11/23, though that's where the similarity ends, as it implemented a new bus with completely different option cards and an incompatible interrupt system making it all but impossible to run unmodified PDP-11 programs. It had really nice graphics for 1982, but instead of the usual choices its intended system software was the laughably named Professional Operating System, or P/OS — execrated for its sluggish menus and limited feature set, of which people were only too quick to make the obvious joke. You could get CPU option cards like the DECmate II's to also make it into a weak PC or a weak CP/M machine, but they ran through P/OS too, and they weren't cheap. At the same time, however, in order to be the most inexpensive PDP-11 system ever, the low-binned DEC Professional 325 didn't even have a hard disk.

All of these systems were originally meant as commodity machines for office work, yet more or less with the exception of the Rainbow, they couldn't run much that office professionals actually wanted to run and little that existing PDP users did. Still, despite questionable technical choices, these machines (the Pros in particular) are some of the most well-built computers of the era. Indeed, they must have sold in some quantity to justify the Pro getting another shot as a high end system. Here's the apex of the line, the 1984 DEC Professional 380.

The Pro 380 upgraded to the beefier J-11 ("Jaws") CPU from the PDP-11/73, running two to three times faster than the 325 and 350. It had faster RAM and came with more of it, and boasted quicker graphics with double the vertical resolution built right into the logic board. The 380 still has its faults, notably being two-thirds the speed of the 11/73 and having no cache, plus all of the 325/350's incompatibilities. Taken on its merits, though, it's a tank of a machine, a reasonably powerful workstation, and the most practical PDP-adjacent thing you can actually slap on a (large) desk.

This particular unit is one of the few artifacts I have left from a massive DEC haul almost twelve years ago. It runs PRO/VENIX, the only official DEC Unix option for the Pros, but in its less common final release (we'll talk about versions of Venix). I don't trust the clanky ST-506 hard drive anymore, so today we'll convert it to solid state and double its base RAM to make it even more professional, and then play around in VENIX some for a taste of old-school classic Unix — after, of course, some history.

The KIM-1 that sounds like Stephen Hawking (or: "jitbanging" DECtalk)

My 1976 briefcase Commodore/MOS KIM-1, a 1 MHz single-board computer with a 6502 CPU and 1K of RAM, has learned to talk — with a familiar-sounding voice.

The KIM-1's serial lines are connected to the last and smallest member of Digital Equipment Corporation's true DECtalk hardware speech synthesizers, the 1994 DECtalk Express. The DECtalk's classic default voice heard in this video is Perfect Paul, which (with adjustments) was the voice of Dr Stephen Hawking as produced with the 1988 Speech Plus CallText 5010.

The 15 keys we can read off the KIM's hexadecimal keypad are polled by a "talker" program that sends the DECtalk Express words and phrases to speak. However, although the KIM-1 has 20mA current loop output you can turn into RS-232 serial, its built-in ROM routines can't reliably communicate at the 9600 baud rate the DECtalk Express demands.

So, in today's entry, we have a veritable smorgasboard of geriatric geekery: using our KIM-1 serial uploader to push a program for execution, let's write a bitbanged 9600 baud serial transmitter routine in 6502 assembly and let the KIM-1 have its say — and crack the DECtalk Express open and look at the insides while we're at it. (Teaser: you'll find its CPU very familiar.)