Unknown VLSI VL82C201

A fast VLSI 286 motherboard. With details on configuration and software tools. Testing and benchmark data.

Although not one of the latest 286 chipsets, the mid-life VLSI VL82C201 seems to be a strong performer, pulling in some excellent benchmark scores:

• https://www.vogons.org/viewtopic.php?p=463421#p463421
• https://www.vogons.org/viewtopic.php?f=25&t=65395

This board was offered to me by a member of the Vogons.org DOS gaming forum, in fact the same individual who benchmarked a similar board to the results seen in the second of those links above.

From left to right: Ekb's VL82C2012, pshipkov's VL82C2012, my VL82C2012

Compared to the boards in the benchmark results above, mine has only 6 ISA slots (4x 16bit + 2x 8bit) versus 7 in the others (although 3x 8bit slots is not massively useful for gaming purposes).

Other than that, the layout and memory configuration looks to be the same.

They all have the same revision of the VL82C201 chipset, all specifically the VL82C201-16Q configuration. They all have 4x 30pin SIMM slots (or the equivalent SIPP sockets) plus a bank of DIP sockets. All have socketed processors. All use twin 27C256 EPROM's for BIOS.

The one thing which I could see counting against similar performance of my board is that the chipset is not quite as closely clustered together; the shorter transmission lines of the other two boards would definitely be beneficial at clock speeds which are otherwise borderline.

One thing which needs consideration with these boards is that they use a oscillator speed divisor of 1/4, rather than the typical 1/2. So if you want to play with the board/processor frequency, then you'll need oscillators of 80MHz for a 20MHz processor, 100MHz for 25MHz cpu, and so on. Your typical 32MHz oscillator on another 16MHz board will only drive the processor at 8MHz

There is a higher-specced version of the chipset available in the VLSI chipset database; the VL82C201-20Q which is rated at up to 20MHz bus speed, but I've yet to see any examples of it in the wild.

The BIOS on this board is extremely rudimentary, offering only Video and System BIOS shadowing and no other performance options whatsoever. Unless I can find out the jumper configuration for the board (and therefore if there is an option for ISA clock speed, memory parity settings or wait-state configuration), I will have to assume that this is the only change I can make.

It's fairly poor, really.

The Intel 287XL was fitted into the co-processor socket and no onboard jumpers changed (mainly because they are not documented). It seems to work with whatever settings the board is configured to use.

• Harris CS80C286-25
• 64MHz oscillator (16MHz CPU speed)
• Standard ISA bus clock
• 4x 1MB 60ns SIMM
• VGA 1 Trident TVGA9000 512KB VGA
• VGA 2 Tseng Labs ET4000AX 1MB VGA

The BIOS of this motherboard does not feature any performance options, so what would have been a 'least aggressive' tuning config on other boards is just what you get on this.

• Harris CS80C286-25
• 80MHz oscillator (20MHz CPU speed)
• System + Video BIOS shadowed
• 4x 1MB 60ns SIMM
• VGA 1 Trident TVGA9000 512KB VGA
• VGA 2 Tseng Labs ET4000AX 1MB VGA

• Harris CS80C286-25
• 100MHz oscillator (25MHz CPU speed)
• System + Video BIOS shadowed
• 2x 1MB 60ns SIMM
• VGA 1 Trident TVGA9000 512KB VGA
• VGA 2 Tseng Labs ET4000AX 1MB VGA

I could only get this configuration working with 2 of my 4 1MB 60ns SIMM modules. I suspect that it's going to need some higher quality modules, or higher rated (50ns?) chips.

As it is, this is unreliable - not quite as unreliable as the Headland HT12 at 24 or 25MHz, but you certainly wouldn't want to use the system in this state. Again it seems more willing to lock up with the Tseng Labs card than the Trident, just as the other 286 system was.

Games tests are run with the fastest VGA option (normally VGA #2).

Software Versions

• Norton Sysinfo 8.0
• CheckIt 2.1
• Landmark 6.00
• 3DBench 1.0
• ATPerf 2.00
• Comptest 260

Notes

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