Thursday, 29 June 2017

System Profile: Acer AcerMate 386SX/20N [Part One]

A few years ago I acquired a 386 system for 99p from eBay. It was an Acer AcerMate 386SX/20N. I don't know why I got so excited about it - I think it was because it very closely matched the spec of my first PC, which was an Ambra 386SX/25 with 2MB RAM and a 40MB hard drive. I played A LOT of games on that system so this one would make an excellent replacement. This system was a very similar spec and even came with Windows 3.11 installed, along with DOS 5.0.

The seller's pics intrigued me because there was an expansion card in one of the 2 ISA slots, but I couldn't quite tell what it was. It looked like a sound card of some vintage, as it had a DB-9 port and what looked like two 3.5mm jacks. I was wrong. It was an 8-bit network card with an AUI port and two holes in the shield. Nevermind. (I have since replaced this with a 3Com Ethernet card.) Nonetheless, this turned out to be quite an intriguing system.

Its design is completely modular and you can remove all serviceable parts without the need of a single tool. There are two catches under the front panel that allow it to be rotated up and removed.

Once this is gone, the top case needs to be unlocked via the two blue sliding catches on either side. I would worry about these in the long-term, as they are a bit stiff and could be broken if the plastic becomes brittle. With a bit of a shove, the top case slides backwards and lifts off.

This allows easy access to the RAM slots. The expansion slots are located on a riser in-keeping with the small form factor.

Note the metal bar passing alongside the speaker, by the floppy disk - this is the mechanical power switch for the system.

The drive cage and proprietary power supply can also be easily removed from here, revealing the motherboard, which appears to be LPX, but is referred to as 'proprietary' in The PC Engineer's Reference Book [source:].

Note the use of what appears to be an MCA slot for the ISA riser. There were a lot of these floating about when non-IBM MCA systems didn't materialise in any great number. They were also used for VESA Local Bus. Also note the empty sockets next to the BIOS ROM chips. More on those later. Also, it needs a good clean.

All the elements of the system are integrated into the board:
  • Intel 386SX 20MHz CPU with socket for co-pro
  • Dallas RTC (which I replaced)
  • 1MB RAM on-board (I think) plus 4 slots for 30 pin SIMMS
  • Acumos AVGA1A video chipset with 256KB memory
  • Floppy drive controller (3.5" floppy drive included, 2nd drive optional)
  • Fixed disk controller (3.5" Connor drive included, optional upgrade)
  • 2x ISA slots
  • PS/2 mouse and keyboard
  • DB-9 serial
  • DB-25 serial
  • DB-25 parallel
  • DB-15 VGA
  • Fan header (for the single fan blowing over the RAM)
Even power for the drives is distributed, via a Molex connector, from the motherboard itself rather than the PSU, something I've never seen elsewhere. The PSU is a 43W Delta unit with passthrough for monitor (which I opted not to take from the seller - I think it was faulty and I don't need anymore CRTs).

Lots of people complain about the Dallas real time clock, but they're not that much of a pain. Of course, compared to a coin cell, they're less convenient and more expensive, but they're a hell of a lot better than a barrel battery as there's zero risk of the board being corroded to death.

There are some extra features on the motherboard that are hard-wired:

J15 - CPU Speed Selector
I'm guessing that there was a 16MHz variant of this system and that this jumper was set at the factory depending on which model was installed. Saying that, surely the crystal would dictate the speed, so that would suggest they used the same crystal and that the jumper enabled a divider. I guess I could try the other setting and see what happens. It also makes me wonder whether I could replace the 40MHz crystal for a 50MHz one to overclock to 25MHz.

These ones are interesting. Aside from the typo (it should say 'precharge') J13 is for another factory-set option. I know that CAS and RAS are to do with how frequently the RAM is refreshed, and a bit of digging pointed me in the direction of this patent, detailing the 'invention' of half-wait states. The explanation for this is that integer wait states were previously adequate for CPU speeds but, with the advent of faster 286 models and the 386, performance gains could be had by using N+1 wait states, where N is a whole value between 0 and 4. Given that this board is set to the quicker '1/2T' setting, I would guess this was set according to the CPU speed being 16 or 20.

Having written the above, I rediscovered this post by a Chilean member of the Vogons forum. He found a Unisys PC with the exact same Acer board within it, complete with typo and everything. His system, however, came with the 16MHz CPU and, sure enough, it's set to 1T:

[source: 133MHz via Vogons forum]
Interestingly these systems appear to use the old style of using two chips for the BIOS ROM, one for odd bits and one for even. There are also sockets for 'Shell ROM' and 'DOS Rom'. I can't find any info whatsoever on what a shell ROM would do but, given that it's just the *nix term for 'command interpreter, I'm guessing this system could support an embedded version of either Linux or DOS. Without documentation it's hard to tell.

And that brings me onto my next point. The strangest thing about this system is the apparent complete lack of documentation available. In fact this is page is probably the most comprehensive source of info on AcerMate systems. Considering it's from a major manufacturer, who are still going today, you would think that a manual would have survived somewhere in some form. My search will continue but, for now, the only documented record of a manual is in the State Library of Queensland in Brisbane. The lack of an electronic copy suggests a lack of surviving units and, therefore, a lack of end-user enthusiasm for these machines. This general lack of information, the modular design, form factor, and budget pricing suggest that this system was picked up by businesses who wanted to equip a workforce cheaply. Given that governments, businesses and corporations tend to write off and recycle most of their old kit, that would explain the lack of these systems in the wild. The only references I've found to this class of system so far in the press are the following:

[source: Computerworld, 11th May 1992]
[source: InfoWorld 27th July 1992]

So it appears that the network card it came with was a stock option on the N model and I have subsequently upgraded the hard drive to a larger model, but the BIOS restricts the size to 500MB.

At least I managed to find some technical documentation detailing the jumpers on the board:
[source: The PC Engineer's Reference Book Volume 2: Motherboards]

This means I have the option to upgrade the Acumos chipset (later acquired by Cirrus Logic) by disabling the internal graphics but no other options to speak of. And I don't know whether I would call any ISA alternative an 'upgrade'.

The BIOS itself is nice and simple. It's by Acer themselves, rather than AMI or Phoenix, and provides not only the usual configuration options but also a low level format option for the hard drive, should one be installed. Interestingly, PCem has the 25MHz model of the AcerMate on the list of machines it can emulate, although it looks like the graphics chipset differs [source:].

Later models based on the 486 and beyond had a slightly more standard case, which could accommodate a CD drive plus another 5.25" device (or a 3.5" device in a bracket). Note the unusual placement of the hard drive in the final pic.

Acer AcerMate 600 [source:]

Internal view of RAM, CPU and ISA slots [source:]

Top-down view illustrating placement of components, including what appears to be a Sound Blaster 1.5 [source:]
Despite the lack of official information, it seems there are a lot of AcerMates floating about the Internets, particularly in Russian museums. I found another article here, written by a Russian enthusiast, which sheds a little light on why these systems seem to be so prevalent in Russia. While retelling the ramblings of the friend he acquired his AcerMate 450s from, he says 'then followed the story that this Acer was at a time in any financial institution (maybe even the ministry?), the bank and the FSB, and even in all these places at once'. Google translate not doing the Russian language any justice whatsoever, but giving my theory of who bought these systems some credence.

In terms of the games I would play on this system, this would be based on what I played on my first computer in 1993 and in 1994 prior to upgrading. Most are early VGA games, plus some EGA examples, that ran quite comfortably. Given that the 486 had been around for about 4 years by this point, and the Pentium was not far off, games were already starting to push the limits of the hardware and some were appearing on CD-ROM. As a result, I played quite a few games that didn't perform brilliantly on my lowly 25MHz 386, so they would perform even less well on this Acer system. Plus I only had a 40MB hard drive so was limited in what I could install. Anyway, here's a list of games with links to the excellent and the year they were released, with some images:

Beneath A Steel Sky Car & Driver Alien Carnage
CD-Man Duke Nukem F29 Retaliator
Grand Prix Circuit Jazz Jackrabbit Lemmings
Major Stryker Paranoid Sensible Soccer
Speedball II T2: The Arcade Game Wolfenstein 3D

Alien Breed (1993)
Alien Carnage aka Halloween Harry (1993)
Alone in the Dark (1992)
Beneath a Steel Sky (1994)
Bio Menace (1993)
Cannon Fodder (1993)
Car and Driver (1992)
CD-Man (1992)
Commander Keen Series (1992)
Desert Strike (1994)
Doom (yes, really, but in a postage stamp) (1993)
Duke Nukem Series (1991)
F117A Stealth Fighter 2.0 (1992)
F29 Retaliator (1990)
Formula One Grand Prix (1992)
Freddy Pharkas: Frontier Pharmacist (1993)
Grand Prix Circuit (1988)
Hocus Pocus (1994)
Indianapolis 500: The Simulation (1989)
Jazz Jackrabbit (1994)
Jetfighter II: Advanced Tactical Fighter (1990)
Knights of the Sky (1990)
Krusty's Super Fun House (1992)
Lemmings (1991)
Lotus: The Ultimate Challenge (1993)
Major Stryker (1993)
MegaRace (1993)
Mortal Kombat (1993)
Paranoid (1993)
Pinball Fantasies (1994)
Project-X (1994)
Seal Team (1993)
Sensible Soccer (1993)
Spear of Destiny (1992)
Spectre (1992)
Speedball II: Brutal Deluxe (1991)
Syndicate (1993)
T2: The Arcade Game (1993)
The Duel: Test Drive II (1989)
Theme Park (1994)
Wacky Wheels (1994)
Wolfenstein 3D (1992)
X-Wing (1993)
Zone 66 (1993)
Zool (1993)

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