Sunday, November 15, 2015

Intel 4004...

Intel 4004...  This was the very first microprocessor, and it has a special place in my memory.  Today is the 44th anniversary of its announcement, on November 15, 1971.  It wasn't immediately available; in fact, it wasn't available to ordinary individuals until about 3 years later.  I don't remember the exact date, but sometime in 1974 – about 41 years ago – I bought one of these magnificent parts.  Mine looked just like the photo above, with a ceramic case and gold-plated (literally!) pins and lid.  It was an expensive part when sold at retail – over $100, as I recall.  At the same time, I bought a kit from some long-gone company.  It was a bag of parts and a schematic; the entire kit had to be wire-wrapped.  The schematic was the key bit.  I had never designed anything like a microprocessor before, and having a schematic was mighty comforting.  There was also a PROM (programmable read-only memory) with a small test program.  I put the thing together in a single evening, staying up until quite late to do it.  The “input”  was a set of four toggle switches and a momentary push button; the “output” was four LEDs.  I fired it up, and it worked – first try!  Then I spent weeks understanding what I had built, and what it could do.

After exhausting the things I could do with a 4004 (they were ... not very powerful), I then built an 8008 kit, an 8080 kit, and finally tried my own hand at designing with a Z80 board, a Motorola 6800, a Mostek 6502, and even a Motorola 68000.  Somewhere along the way I also built a bit-slice machine, 16 bits wide based on four AMD 2901s.  The 4004 launched all that learning for me, and, in a significant way, launched my career.

Happy birthday, little 4004!


  1. My first exposure to CPUS was also the 8080, Z80 and Motorola 68000...that was quite a few moons ago..... :) wayyyyyy before I knew who Intel was.

  2. Hi, Dave! Yes, that certainly was a few moons ago :) I ended up doing more with Z80s than with any other processor, mostly because of CP/M compatibility and that great peripheral chip set they had, that made it so easy to use for embedded systems of any kind. Did you know that they still make the things? Check it out: