Great news. The front panel (FPMini) has finaly been completed. I spent the last month working out the switch footprint issue. Somehow on the last prototype board all of the switches had the oposite function than what was printed on the silkcreen. I got that sorted out but the autorouter was having fits. It's takes a solid week running 24x7 to get the board routed. I had to restart several times.
There has been a lot of interest in the board from the N8VEM S100 google group. I've recieved request for nearly 50 PCB boards. In addition to the PCB boards folks were also interested in switch sets. We put together a group buy from NKK to get the best price possible. Purchasing in a larger quanty sure did help. It brough down the price of a switch set to $80 from $105. Thats a $25 savings which can buy a nice handful of parts. Our switch order totaled 40 sets. Nearly 900 separate switches.
PCB and switch order was placed on Friday Aug 29. PCB's should be here first week of September. Switches are being made by NKK and are not due to arrive until November.
Hey folks. Sorry it's been so long since there's been any activity on this project. There's been some great developments during this ideal period that were worth waiting for. Crusy (Josh) has developed a great companion 8080 CPU card which is a fantastic single board S-100 computer board. Card has an 8080 CPU, 64K Static RAM, 2 serial ports, three parallel ports, SD card slot for booting CP/M and front panel connectors for the IMSAI or ALTAR systems. S-100 nerds can now build a complete S-100 computer system with only two boards and a small backplane.
We had a few problems with the Beta two version of the PCB. After some awesome testing by Crusty and Rich we believe to have all the issues worked out. FPMini board has been tested and reporting working in S-100 systems with Z-80 and 8080 CPU's.
Schematic's been updated. PCB auto routing completd and all manufacturing files were generated. This should be the final first production ready PCB.
Request for PCB quotes went out and I'm close to placing an order for about 60 boards. Theres been a lot of interest from the S100 N8VEM group. I'm also putting together a group pruchase for the very nice NKK mini toggle switches needed for the board.
PCB order will be going out in mid August 2014. Manufacturer does not have sufficient quantity to fill our order so were looking at a 10-12 week lead time. Currently theres interest in 31 sets of switches for a total of 651 switches.
If your interested in techincal details please visit my build page at N8VEM S-100 FPMini
You will also find there the S-100 8 slot terminated backplane and Crusty's 8080 SBC.
The FPmini spent a good couple weeks in the auto router. It probably could run longer but wouldn't have any drastic improvements. The via count got down to less than 200 which is good for a board this size.
Quotes are back from the PCB manufacturer and were ready to pull the trigger. Our only decision left is to determine how many boards we want. An email went out to the group looking for a few additional builders/testers.
If you'd like to see images of the completed board use the links below:
Have you ever wonderd how all the traces on a PCB board are done? What's a trace you ask? A trace is a electrical connection that connects the electronic components on the board. Traces are very thin copper layers (think of them as flat wires) on the top and bottom of the board. More complex boards can have these traces sandwidtched inbetween the board to create three, four, five and more layers.
There is a fantastic tool out there called Freerouter (http://freeerouting.net).
When looking at the board's rats nest (connections from component to component) we see this:
Here is a screen shot from a running autorouter session as it is running and figuring out how to place the traces. The autorouter can take several days to complete a board. It performs numerous passes to optimize the traces. One function of the auto-router is to eliminate as many of the vias as possible. A via is a tiny hole that connect traces from one side of the board to the other. We like to have as few of these via's as possible. Another function of the auto router is to have the shortest path possible between components.
Pretty cool huh?
The auto-router generates a session file. This can then be imported into the KiCad program and you end up with a routed board. It's not quite the final version which is sent off to be manufactured but it's close. Here's a screen shot of the routed board from the design program (KiCad):
Good news! I just wrapped up the final schematic and board layout
changes for version two prototype board. I will still need to verify
all of the changes got included and nothing got left out so there's a
bit of verification to be done. Once that's complete I will start
auto-routing the board. Version one board took about a week to
auto-route however the actual time was more like three weeks. When
auto-routing is complete the board design is run through a DFM (Design
for manufacturability ) tool to identify any possible manufacturing
problems. This includes things like traces being to close together,
problem with ground and power plans, etc. Once any DFM errors are
corrected the auto-routing has to be restarted and the entire cycle
starts again. Since this is the second version I'm not anticipating
too many restarts.
We are feeling real good about prototype number two and are hoping it
will be the final prototype (oh, did I just jinx us by saying that).
Prototype PCB manufacturing takes about three weeks. Were hoping to
start building and testing by mid April. After the board has been
finalized I'll post the schematic and board layout for your viewing
One significant change we made was to remove the AC power switch.
Having AC current flow on the same board with low voltage TTL made a
some people nervous. All that current flowing through those large
traces can cause some serious damage should there be a short. It also
presented a safety issue since the power pads are at the top of the
board (I can testify to that. I made the mistake of grabbing the board
and learned some new respect for it). Most S-100 systems already have
an external power switch so I doubt it would be missed. We feel this
is a positive change plus it enhances reliability. It also freed up
precious board real estate which is needed to add additional driver
logic for the LED displays (future enhancement). This will help the
board run at faster clock speeds. The design is pretty much limited to