View Full Version : Two new S100 Boards from S100Computers.com

August 9th, 2016, 06:01 PM
I am delighted to announce two new S100Computers boards.

The first is the “Full Size” 80486 CPU board. This board is the result of two years of work and more prototypes than I care to mention. It is by far the most difficult board I have done to date. It places the 80486 on the S100 bus such that it can “on the fly” operate in 8, 16 or 32 bit modes. It works with all the previous S100Computers boards and on an active terminated S100 bus operates with a Phi Clock of 10MHz. In this mode the board can address the full 16MB or RAM available on the bus.

In the CPU “Protected Mode”, the board utilizes our OTT bus connector to address RAM with a range of up to 4GB. In protected mod the CPU clock signal is 20MHz for 32 bit RAM access. Current S100Computers boards utilize static RAM with a max capacity so far of 64MB. A 4GB DRAM S100 board is currently being prototyped utilizing the above OTT bus interface.

A description of the board can be found at the bottom of this page:-


Almost all the S100 bus control signals are synthesized within the 1508 CPLD on the board. This allows users to program the S100 bus as they see fit and offers tremendous flexibility. Source code is provided.

Because of the complexity of the circuits, this board is our first four layer S100 PC board. This will increase to cost of the bare boards to at least $32/board. That said this board should be the last Intel 8086 style S100 board you should need. It supersedes all our previous 8088, 8086, 80286 and 80386 CPU boards. If you just want to run the board in real mode with MSDOS etc. I would even recommend it to relatively new users. For protect mode applications however be prepared for some heavy lifting with the programming.

The second board is a 16 Bit VGA board. This S100 board utilized the Trident VGA chip. We previously had an 8 bit board which worked (only) with our 8088 CPU board. This board incorporates 16 bit wide video RAM and works with both the Baby and Full Size 80486 boards. Note it will NOT work with the earlier S100Computers 8086, 80286 or 80386 boards.

One unique aspect of this board is the use of an adaptor board to house the SMD Trident chip. These adaptors are commercially available but I made a special one with extra-large pads to make soldering the chip easier. They are dirt simple single sided boards. I got mine made at Advanced Circuits for $33 each. I would like to see if somebody here could take on getting a bunch of them made. I can supply the KiCAD/Gerber files. There are a number of these VGA chips out there. My plan is to utilize different adaptors on this S100 board. More on that later.

A description of the board can be found at the bottom of this page:-

Both boards are now available separately for a group purchase. The 80486 will run about $32/board + shipping, the VGA board $16/board + shipping. Please don’t enquire about payments… , always they will be via PayPal after you receive the board. Delivery will take about 1 month from now. Please respond only to this tread if you want boards. If you have not received boards before from S100Computers.com you will need to send me your shipping address. Send to monahan AT vitasoft DOT org.

John Monahan