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Thread: When did circuit board CAD really take off / begin?

  1. #1

    Default When did circuit board CAD really take off / begin?

    I'm working on a microprocessor trainer emulator (for fun). The hardware is pretty well planned at this point - it is going to use an ATMEGA1284 microcontroller, 6 seven segment displays, 6x4 Cherry mx keypad, eeprom ic's for drives, two serial ports, i/o expander for some 16 i/o's, and a piezo. I'm trying to pattern it style wise after the microprocessor trainers of the 70's/80's. I've seen pcb's that have hand drawn traces and while I'm certainly not about to do that, I can simulate its look in Eagle by using the miter command. I wonder if pcb's of the time had a flooded bottom layer/side - or if they just tried to route the grounds on thicker stronger traces. Then I looked at some pics of the SDK-80 and SDK-85 and I noticed they have uniform traces with 45 degree angles that are not hand drawn. Were they using layout software on them?

  2. #2
    Join Date
    Jan 2007
    Pacific Northwest, USA
    Blog Entries


    CAD for PCBs goes back to at least the 1960s--proprietary software running on mainframes. No auto-routing per-se--the engineer sketched his layout and tracks on a sheet of paper, the design was digitized and then manipulated on the computer. Not exactly what we'd normally think of as mature CAD, here's a monograph from 1969.

    But for the average engineer in the 1970s, PCBs were either ink-and-tape on mylar, or rubylith done several times actual size. Xacto-knife time. ICs were similarly laid out but using much greater magnification. I got my first exposure to PCB on an IBM XT using OrCAD 1.0 (still have the floppies).
    Last edited by Chuck(G); June 13th, 2020 at 05:42 PM.

  3. #3


    I was reading about OrCAD when I searched for early EDA earlier.

  4. #4
    Join Date
    Sep 2006
    Silicon Valley


    I'm pretty sure IBM SLT modules were computer routed on their .1 grid hole layouts, ca. early 60's

    DEC had in-house software on PDP-10s (SUDS)
    You can see a picture of someone doing board digitization on a PDP-8 in one of the PDP-8 handbooks, late 60's

    Lots of people in that space by the 70's

    Commercial vendors, Racal-Redac on PDP-15s, later on PDP-11s

    Companies supplying computerized drafting, Calma, Computervision.

    80's workstations, Daisy, et al. wiped out by companies with 32bit PC software by the mid-80s who came out of the 16-bit PC
    world, Autocad, EEtools, Orcad, etc.


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