1993 mainboards

Octek Jaguar V

This was the time when the 386DX-40 was all but universal, and the board at right is as typical an example of a DX-40 board as any: it is about two-thirds of Baby AT size; it has the classic RAM arrangement of 8 30-pin SIMM sockets in the right-hand back corner of the board; and a clean, simple layout. If memory serves after all these years, this was a model we sold a good number of.

Early on it was common to fill all eight RAM slots with 256k SIMMs to make a 2MB system; that soon gave way to four 1MB SIMMs as the standard, or even 8MB for power users. 4MB SIMMS were available already but still very rare. Notice the small black heat sink on the CPU — a very unusual thing in those days: DX-40 chips ran quite warm to touch but rarely overheated.

• CPU support: 386DX: AMD 386DX-40 surface mounted, 387 socket provided.
• Speed: 40MHz.
• Slots: 4 ISA, 2 8-bit
• I/O: None.
• RAM: 8 30-pin SIMMs, up to 32MB.
• Cache: None.
• Chipset: MX 305/306UMC 481/482, AMI Color BIOS.
• Date: Probably '93, maybe late '92.

MG 8517 386SX-33

The 386SX was fading fast by this time, but would still sell for a while longer in that curiously ill-defined section of the market where the cheapest, slowest new products contend with late-model second-hand items. The MG board illustrated is typical of the last of the 386SX boards: four SIMM sockets, single chip chipset, no cache RAM, and everything squeezed down into the smallest possible space.

There would be a small number of similarly miniscule 386DX-40 boards around the end of 1993, but those aside, the tiny one-third Baby AT form would not reappear until 1999, and then only very briefly.

In fact, one of the downfalls of the 386SX as a new product was that the manufacturers all switched to 4-SIMM designs to get the size (and therefore cost) down. 2MB of RAM was all but essential by this time and to do that in a typical new SX board with only four slots you needed two 1MB SIMMS, where in a standard 386DX-40 board you could use eight cheap second-hand 256k SIMMS. Before too long, as the value of 256k SIMMs dropped and the price of new RAM went up ('93 was the year of the great resin factory fire RAM shortage and panic, remember), it was actually cheaper to provide a 2MB DX-40 than it was to make 2MB SX-33.

• CPU support: 386SX: Intel SX-33 surface mounted, 387SX socket provided.
• Speed: 33 MHz.
• Slots: 6 ISA
• I/O: None.
• RAM: 8 30-pin SIMMs, up to 32MB.
• Cache: None.
• Chipset: ALI M1217, AMI Color BIOS.
• Date: January 1993.

UMC 386DX-40

No date for this one, but probably mid to late 1993 — notice the silver markings just to the right of the right-most ISA slot (just left of the NPU socket): the legend "87DLC" gives the hint: this board was designed to take either the 386DX-40 or the 486DLC and is unlikely to have appeared in '92. It is unidentified but the style of the layout and the model number suggests that it was possibly a Gigabyte.

Perhaps one-third of the way through the DX-40's reign, it became fashionable to add some on-board cache to improve performance. Earlier on, cache had been something reserved for only the most expensive boards, now it was appearing on mainstream products like this one. You can see the eight cache RAM sockets at lower right: four are empty, the other four each have a 20ns 256kb chip to make 128k in total. The horizontal chip just below them is a 64kb tag RAM chip.

It is more than ten years since we sold new 386DX-40 boards and we did not take notes at the time so all this is from memory — but we hardly ever used to find DX-40 boards that were problematic. More than likely, this model was as bulletproof as the rest of them.

• CPU support: 386DX or 486DLC: AMD 386DX-40 fitted, 387 socket provided.
• Speed: up to 40MHz.
• Slots: 6 ISA, 1 8-bit
• I/O: None.
• RAM: 8 30-pin SIMM sockets, up to 32MB.
• Cache: 128k 20ns, expandable to 256k.
• Chipset: UMC 481/482, AMI Color BIOS.

MG TK 82C480

An early example of the general style of board that was to become very common indeed over the next year or two, in many ways as typical a 486 board as you could ask for. It had the now-standard RAM slots, AMI Color BIOS, one of the most common chipsets, the all but universal VESA 486 size — just long enough to fit the VESA slots — minor connectors sensibly spaced out at front left, and cache RAM sockets in the front right corner.

There are unusual things about it too though. First, the cache RAM sockets are all empty. This was a common enough trick used by low-rent retailers to use to save about $50 worth of cache chips, but not something that was normally done by reputable dealers — and from the warranty label on the keyboard BIOS chip, we know that the illustrated board was originally sold by one of Ballarat's better outfits. This was around the time that they became dissatisfied with their former buying group; perhaps this was one of the reasons. But why remove the cache RAM from an MG board? At least to judge by the 386DX-40 boards of theirs we sold ourselves (see below) MG was a fairly good brand. It would seem to make more sense to pull the cache out of a cheap board.

Second, notice the silver clock crystal at front right: short of physically changing the 25MHz crystal, this board was still, like nearly all boards before this date, limited to running at a fixed frequency; you couldn't just plug in a DX-33 and swap a jumper to upgrade it the way you could with the boards that followed. (You could plug in a DX-2/50 though: the two just-visible jumpers between the CPU and the VESA slot were for switching between SX and DX and DX/2.)

Third, an MX special: for some reason best known to themselves, MX boards always came with a stiff, clear plastic anti-static backing. You can just see the edge of it poking out from under the board near the clock crystal. This was probably quite a good idea but techies didn't like it because of the way that the plastic used to catch on the mainboard mounting standoffs. All too often, after struggling for five minutes to get a board to fit into a flip-top case, you would swear one or twice and then just tear the plastic off and throw it away.

Even allowing for the lack of cache RAM, by the way, this board and its 486SX-25 CPU would have cost around 50% more than a 386DX-40 board and had nowhere near the performance. SX-25s had very little to recommend them. Here at Red Hill, in 1993 we hardly sold anything else except 386DX-40s.

• CPU support: 486: Intel 486SX-25 fitted.
• Speed: 25 MHz.
• Slots: 2 VESA, 4 ISA, 1 8-bit
• I/O: None.
• RAM: 8 30-pin SIMM sockets, up to 32MB.
• Cache: None fitted, up to 256k.
• Chipset: UMC 481/482, AMI Color BIOS.
• Date: 11th June 1993.

MG 38606

An MG 386DX-40 board. By coincidence, this one has the same retailer's warranty labels and was sold in the same month as the MG 486 above, but we sold quite a few of this model too. Although MG trumpeted their "made in the USA quality", we found them to be fussier about RAM than our usual Taiwanese boards and no better than average. In 386DX-40 boards, though, "no better than average" was pretty damn good! In fact, we were not to see such consistently low across the board failure rates again until early in the new century.

• CPU support: 386DX or 486DLC: AMD 386DX-40 fitted, 387 socket provided.
• Speed: up to 40MHz.
• Slots: 5 ISA, 2 8-bit
• I/O: None.
• RAM: 8 30-pin SIMM sockets, up to 32MB.
• Cache: 128k 20ns, expandable to 256k.
• Chipset: UMC 481/482, AMI Color BIOS.
• Date: 22nd June 1993.