An S-100 Prototype Board
If you do any kind of serious "homebrew" work with your
S-100 system you will need a "Prototype Board". This is a
card that fits into your S-100 bus and brings the bus edge connector pins (all
100 of them) up on to the board. Almost from the very start
companies supplied these boards for what was at the time a hobbyists market.
Here is a picture of a typical board:-
Typically you laid out the chips horizontally (although some vertical
orientation boards were produced). These board can be found on
places like eBay from time to time. When later non-DIP style
chips (CPU's etc.) started to appear these boards did not work. One or two
companies offered boards with just 0.1" pad spacing or a board with at least
an area with this format such as this
Connecting the IC pins together can be done either via wire wrap or
point to point solder techniques. There are pros and cons to
each method. Here are two examples:-
A Buffered S-100 Prototype Board
Personally I prefer the point to point soldering
method. It takes longer to do initially but in the end you save time
debugging because it is easier to locate connections and make changes.
One of the frustrating aspects of doing a new prototype board design is that
before you can do anything useful you have to connect up all the address
lines (24) , data lines (16) and numerous control line to buffers on the
board. Each requires an input line from the bus and an output line to
the functional area of the board. For almost every board they will be the
same. To take the drudgery out of this a "buffered prototype S-100" board with all these connections already
done. Here is a picture of the board:-
There are distinct pads for all the major buffered S-100 lines. You can
start right away utilizing the board for what you had in mind. The
schematic for the board is quite simple and can be seen
The layout for the board can be seen
here. There are pads for a +5V, +12V and -5V or -12V voltage
regulator. The only slightly unusual thing is U108, a 74LS245 buffer
that may be used to transfer data to/from the 8 bit data In/Out lines. This
can sometimes be of use for interrupts in 16 bit systems. Unfortunately its
on the S-100 side of bus buffers and so cannot be used for 16 bit CPU data
transfers if you wanted to use this board as an 16 Bit CPU prototype board.
I have use this board for a number of S-100 prototype boards. Here is
a picture of it being used for the first
V2 of the Buffered S-100 Prototype
Having utilized a number of these boards, I realized that a few little
tweaks would make a big difference. A
second version of the board was made. This board has in addition to the board
1. I/O port selection
circuitry that can be jumpered for any 8 bit I/O address range.
2. A complete bi-directional buffer (U108) setup for
8/16 bit data transfers with 16 bit CPU's.
3. A dedicated 5V line across the bottom of the "patch"
area for convenient hookup to IC's.
4. Complete flexibility as to the type or Voltage
regulators used in each of the 3 positions.
The schematic for the V2 Prototype board can be obtained
here. The board layout can be obtained
The board utilizes
74LS682's for port addressing. If your are unfamiliar with this technique
A Production S-100 Board
Realizing that a number of people might want to utilize a
board like this together with a group of
people on the
Groups S100Computers Forum, "group purchases" are made from time to time.
Contact and join the group if you would like to be involved in this
project. See if bare boards are available and/or see if you and others may
be interested in doing another board run.
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 PROTOTYPE BOARD SCHEMATIC
(V2, FINAL, 7/4/2010)
CURRENT PROTOTYPE BOARD LAYOUT (V2, FINAL,
KiCAD files for this board (S100 Prototyping Board-002.zip
Other pages describing my S-100 hardware and software.
here to continue...
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