A1 Scaler progress. Just decoupling caps and connector left.

I think I am going to make the caps 0805s for the rest of the modules.

#retrocomputing #74hcagc #apollo #agc #agcreplica

74HC02s soldered onto the A1 Scaler board.

I have to stop so I can be a responsible adult and go to work tomorrow....yes the flux will get cleaned off when the board is done.

Hand soldering 603 package capacitors is annoying! May make them 805s for the rest of the boards, this one is a prototype to test construction as well.

#retrocomputing #apollo #agc #agcreplica #74hcagc

Putting away a couple other projects to make room for building the first AGC board this weekend.

Received my Digikey order. I am using Texas Instruments 74HC chips.- TI supplied micrologic packages for the original AGC in the 60s, and there are the last supplier standing so it just felt right.

What have I gotten myself into?

#retrocomputing #apollo #agc #agcreplica

The PCB layout work for my 74HC-AGC project is all being done in #KiCAD on my HP Dev One running Pop!_OS from @system76 @pop_os_official.

Months in and the Dev One is still an excellent piece of hardware and Pop!_OS is running strong.

PCBs for the 74HC-AGC A1 Scaler module should be here next week, then I need to solder them up and do some testing to verify the gate propagation delay is within a range that will work.

#retrocomputing #apollo #agc #agcreplica

Approved fab of A1 Scaler module PCBs for the 74HC-AGC with JLCPCB. This is the first time I have ordered a 4-layer board.

Time to order a bunch of 74HC02, 74HC27, and 74HC04 chips from Digikey.

Hoping that I made it in the window before the New Year breaks at the PCB fabs, I really want to get one module built and tested to start to build some momentum.

#retrocomputing #apollo #agc #agcreplica

Routed the A1 Scaler module, now that it seems that a backplane is possible. Worked really well as a 4-layer PCB, routed and optimized in just a couple of hours.

I think I'm going to call this project the '74HC-AGC', for the logic series I will be using.

Now I just need to take the plunge and order the first PCBs for this crazy project.

#retrocomputing #apollo #agc #agcreplica

Freerouting optimized via count for the AGC replica backplane proof-of-concept down from 1550 (yesterday AM) to 1012 (today PM). Pretty impressive to see a 50% reduction.

One thing I noticed is that the main routing algorithm seemed to only load up 1 CPU core, but the optimization routine to reduce via count/trace length that runs after everything is routed loaded up all 16 cores on my 5950X.

#retrocomputing #apollo #agc #agcreplica

Proof of concept routing of the backplane for an Apollo Guidance Computer in 74HC logic.

Lots of things to do to turn this into a real thing. Freerouting did the job for this proof of concept at 6 layers but I need to add mounting holes, another giant 360 pin 'outside world' connector, and 5 more modules (Power/Oscillator, A25-A29 interface modules).
By the time I do that, I think at least 2 more layers will be needed.

#retrocomputing #apollo #agc #agcreplica

The Freerouting auto router actually succeeded in routing the 2800 point to point connections on a backplane for a 7400 series logic implementation of the Apollo Guidance Computer.

Excited to make some progress on this project!

#apollo #agc #agcreplica #retrocomputing

Finally a little bit of a family resemblance after months of looking at just schematics.

Now to find out if Freerouting is up to the task.

#apollo #agc #agcreplica

(Photo of actual AGC from https://www.ibiblio.org/apollo/ElectroMechanical.html, taken by Mike Stewart during the restoration of a real AGC a couple years ago)

This is quite the ratsnest.

#apollo #agc #agcreplica

Major progress today on the #apollo #agc #agcreplica

Hoping to hit 'run' in Freerouting on a first draft of a backplane PCB overnight tonight. A few things to work out on the DSKY interface, so not ready to fab but I need to know if this can be auto-routed or not. (If not, the entire backplane may need to be wire-wrapped by hand.....)

If the 12x24" version (roughly the footprint of the real AGC) routes, then I have some ideas to cut the size down to save $$$ on the backplane.

Getting the pinouts for the A51 & A52 connectors onto my AGC Backplane schematic. These are the connectors used for testing on the ground and connecting to the rest of the Apollo CSM (although I'll only use the test connector)

Once I have these in, it's on to defining footprints for the connectors and then laying out a PCB.

#apollo #agc #agcreplica

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24 out of 24 backplane interfaces.

Now I need several hundred pins of the connectors that connect the AGC to the outside world.

#apollo #agc #agcreplica

I wonder if anyone has a CNC controlled wire wrap machine (where it drives the wrap tool around automatically and makes the wraps) in a dusty corner somewhere and might be willing to let me use or revive it..... Would be neat to wire wrap the AGC replica backplane. And possibly easier to debug/make small changes then a PCB.

#apollo #agc #agcreplica

Working on the #apollo #agc #agcreplica backplane schematic some more tonight. 7 more modules to import into the backplane PCB, then I need to define the 2 connectors that connect the AGC to the outside world.

Then I need to define footprints for all of the connectors.... Then I can think about routing.

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