This S-100 backplane is an 9 slot
active terminated motherboard for building and/or repairing small S-100
systems. It is primarily intended for bench-top work to repair and/or build
boards without risking valuable legacy S-100 chassis. The builder supplies
their own power supplies, connectors, and other components. The S-100 prototyping boards are $32 each plus
$3 shipping in the US.
This board is a copy of an 8 slot board (shown below) done by Andrew Lynch
a number of years ago but
with added features.
• 9 SLOT (One more slot added)
• Active Termination (copied from v 03)
• 1st SLOT is spaced 1” from other slots to accommodate IMSAI Style chassis.
All other slots are spaced the usual 0.75”
• Mounting holes for ALTAIR and IMSAI chassis. Hole size 0.138” (6-32
• Two power connectors with different pin outs.
o P1 with 0.2” (5.08mm) spacing. Hole Size 0.060”
o P2 with 0.156” spacing. Hole Size 0.065”
• Expansion Connectors with multiple function
o Expansion IN/OUT
o Test point
o Active Termination
• Jumpers to ground some S-100 pins as needed by IEEE-696.
o Pins 20, 53 & 70. (Pin 53 on ALTAIR and IMSAI computers is needed for
Front Panel operations and should not be grounded
when using these front
• Thick board, approximately 0.100”.
• S-100 connectors require 0.25” row spacing. Hole sized 0.040”.
• Fused power.
A new V4 version of this motherboard has been fabricated. Please contact
Josh, AKA "Crusty"
see if one is available.
Note that often S100 motherboards and boxes appear on eBay at very
reasonable prices. These motherboards have "no moving parts" and are often a
quicker/simpler solution to building an initial S100 bus system. A good place to look is
The relevant KiCAD files for this motherboard can be downloaded from the
link at the bottom of this page.
Here is a S100 bus label that can be used as a template on the edge
connectors using Avery® Clear Shipping Labels with Easy Peel® 7665 - 8½" x
11" labels. (Provided by Josh Bensadon).
The links below will contain the most recent schematic of this board.
Note, it may change over time and some IC part or pin numbers may not correlate
exactly with the text in the article above.
CURRENT MOTHERBOARD SCHEMATIC
CURRENT MOTHERBOARD MANUAL (V4 3/8/2017)
CURRENT PDF LAYOUT OF THIS MOTHERBOARD (V4
KiCAD files for this motherboard (V4 3/8/2017)
Other pages describing my S-100 hardware and software.
here to continue...
This page was last modified on