3 ms·

What a godawful mess that must have been to debug. I've never used wirewrap, it looks awful to me. I am trying to imagine what it would have been like to desig

What a godawful mess that must have been to debug. I've never used wirewrap, it looks awful to me. I am trying to imagine what it would have been like to design such a system using only pencil and paper. Going from block diagram to the lowest level, just on big sheets of paper... the pencil sharpeners must have been emptied twice a day.

Gibbon1 1y ago
The existence of wire wrap tells you a lot how painfully tedious it was to layout PCB's at the time. I did a couple of wire wrap boards. But eventually just started soldering wire wrap wire to the sockets. By the early 90's it was faster to layout a PCB and have it fabbed. Bonus you could outsource that and use the 3-4 weeks to do less tedious things. This is just around the time that programmable logic became readily available. It'd be much easier to iterate with that than wiring up logic gates. Last 30 years you can do all this debugging with simulations and then test using FPGA's.
- FarmerPotato 1y ago
  I'm old-young enough to be aware of the evolution of minicomputers implemented in MSI TTL with wire-wrap (1970) to VLSI integration (1975). Examples are the LSI-11 and TMS9900. My first home-brew micro was done in 1987 using the Radio Shack hand-tool and an OK Industries' motorized wrap gun. Now, I add CPLD to my wire-wrap designs! Just like on an iterated PCB, you must lock the physical pins to functions.
  - TheOtherHobbes 1y ago
    Some DEC CPUs were wire-wrapped until VLSI became a thing. The KL-10 was notoriously an ECL wire-wrap design. But they had a semi-automated machine to handle it. I don't think anyone mass-produced non-trivial numbers of wire-wrap boards by hand. It's fine for prototypes, but it's a very error-prone process and makes it difficult to handle noise, especially at fast clock speeds.
- FarmerPotato 1y ago
  Present day: I can fabricate a wire-wrap version from my PCB footprints, much faster than I can route the PCB! With wire-wrap, you can route multiple traces between the same pins, or I like to neatly bundle a whole bus' worth. I'm far more pleased with the results of my wire-wrap, than the quality of my SMT soldering once I get a PCB made. I had a tutor for wire-wrap in the 1980s. But I'm self-taught in PCB routing, and I start it over at least 3 times.
- pjmlp 1y ago
  When I was a kid helping my father with in-house electronics, early 1980's, this meant using specific pens and paper to layout them into boards, and then do chemical baths, drying the boards, and then hope for the best when starting to solder components on top. Usually a mistake in any step would mean throw away the whole board and start from scratch.
rwmj 1y ago
I made wirewrap boards back in the early 90s and it was extremely tedious, both following the netlist instructions to do the initial work, and then the inevitable debugging when it didn't work. Of course you can have two kinds of bugs - either you made a mistake doing the wirewrap, or your design has a problem! For the complexity of the boards I did, I think it took 2-3 days to do the initial wirewrap, and then days or weeks to debug and get it working. It was, however, both cheaper and easier than doing a prototype PCB. For that, I'd have to use the institution's darkroom with their flatbed photoplotter connected to a PDP-something that you had to boot from reel-to-reel tape. The plot happened overnight, and then had to be developed next day in the darkroom, and then if you were lucky you'd have transparencies of each layer of the PCB that you could send off to a local company who would etch you a single PCB for a lot of money in a few weeks. Even that wasn't trouble-free, since PCBs can have manufacturing faults, or you could screw up when soldering the components to the board, or your design could be wrong. It was very rare that I as the most junior person was allowed to go the PCB route. I think for my boards it happened only once on an ECL design that simply wouldn't have been possible with wirewrap. Although I was tasked with doing the transparencies for other team members. Since I was being paid only £40/week through a government benefits scheme, it was much cheaper to pay for my time than to pay an external company. Also as the other reply says, I used CPLDs a lot which were much faster to iterate. With practice you could pull out the QFP package, put it in the programmer, recompile and upload the new logic, and put it back into the board in an hour. Luxury! We never used pencil and paper (except for notes). The software for drawing schematics, laying out PCBs, making netlists, and compiling CPLDs was pretty advanced even then. Although all of it was horribly proprietary. No KiCAD for you. Taught you to check everything in your design early and often.

Gibbon1 1y ago

The existence of wire wrap tells you a lot how painfully tedious it was to layout PCB's at the time. I did a couple of wire wrap boards. But eventually just started soldering wire wrap wire to the sockets. By the early 90's it was faster to layout a PCB and have it fabbed. Bonus you could outsource that and use the 3-4 weeks to do less tedious things. This is just around the time that programmable logic became readily available. It'd be much easier to iterate with that than wiring up logic gates. Last 30 years you can do all this debugging with simulations and then test using FPGA's.

FarmerPotato 1y ago
I'm old-young enough to be aware of the evolution of minicomputers implemented in MSI TTL with wire-wrap (1970) to VLSI integration (1975). Examples are the LSI-11 and TMS9900. My first home-brew micro was done in 1987 using the Radio Shack hand-tool and an OK Industries' motorized wrap gun. Now, I add CPLD to my wire-wrap designs! Just like on an iterated PCB, you must lock the physical pins to functions.
- TheOtherHobbes 1y ago
  Some DEC CPUs were wire-wrapped until VLSI became a thing. The KL-10 was notoriously an ECL wire-wrap design. But they had a semi-automated machine to handle it. I don't think anyone mass-produced non-trivial numbers of wire-wrap boards by hand. It's fine for prototypes, but it's a very error-prone process and makes it difficult to handle noise, especially at fast clock speeds.
FarmerPotato 1y ago
Present day: I can fabricate a wire-wrap version from my PCB footprints, much faster than I can route the PCB! With wire-wrap, you can route multiple traces between the same pins, or I like to neatly bundle a whole bus' worth. I'm far more pleased with the results of my wire-wrap, than the quality of my SMT soldering once I get a PCB made. I had a tutor for wire-wrap in the 1980s. But I'm self-taught in PCB routing, and I start it over at least 3 times.
pjmlp 1y ago
When I was a kid helping my father with in-house electronics, early 1980's, this meant using specific pens and paper to layout them into boards, and then do chemical baths, drying the boards, and then hope for the best when starting to solder components on top. Usually a mistake in any step would mean throw away the whole board and start from scratch.

rwmj 1y ago

I made wirewrap boards back in the early 90s and it was extremely tedious, both following the netlist instructions to do the initial work, and then the inevitable debugging when it didn't work. Of course you can have two kinds of bugs - either you made a mistake doing the wirewrap, or your design has a problem! For the complexity of the boards I did, I think it took 2-3 days to do the initial wirewrap, and then days or weeks to debug and get it working. It was, however, both cheaper and easier than doing a prototype PCB. For that, I'd have to use the institution's darkroom with their flatbed photoplotter connected to a PDP-something that you had to boot from reel-to-reel tape. The plot happened overnight, and then had to be developed next day in the darkroom, and then if you were lucky you'd have transparencies of each layer of the PCB that you could send off to a local company who would etch you a single PCB for a lot of money in a few weeks. Even that wasn't trouble-free, since PCBs can have manufacturing faults, or you could screw up when soldering the components to the board, or your design could be wrong. It was very rare that I as the most junior person was allowed to go the PCB route. I think for my boards it happened only once on an ECL design that simply wouldn't have been possible with wirewrap. Although I was tasked with doing the transparencies for other team members. Since I was being paid only £40/week through a government benefits scheme, it was much cheaper to pay for my time than to pay an external company. Also as the other reply says, I used CPLDs a lot which were much faster to iterate. With practice you could pull out the QFP package, put it in the programmer, recompile and upload the new logic, and put it back into the board in an hour. Luxury! We never used pencil and paper (except for notes). The software for drawing schematics, laying out PCBs, making netlists, and compiling CPLDs was pretty advanced even then. Although all of it was horribly proprietary. No KiCAD for you. Taught you to check everything in your design early and often.