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  • Author Author: ralphjy
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Pong is Alive

ralphjy

As part of the Hardware Hacking Challenge I thought that I'd try to resurrect a Pong game that I built back in 1978.  My intro blog is here: Pong Game Circa 1978

 

Since it came out of my junk box and seemed to be in poor condition I thought that I probably should have proof of life before I invested too much effort in restoring it.  I was somewhat surprised that the 30 AWG wirewrap wire that I had used had oxidized and become brittle.  Some of the wires were actually broken.  I still use 28 AWG wire of the same vintage and the unused wire seems like new.  I guess maybe the wire may have reacted with the metallization of the wirewrap pins.  Anyway, I decided I should rebuild the circuit from scratch - just reusing the ICs and the crystal.

 

So, I cut the circuit board out of the case (who used connectors back then image).

 

Top of the board:

image

 

  • Pong chip AY-3-8500-1 (-1 for NTSC)  Date code 7707
  • 4072 CMOS Dual 4 input NOR
  • 4001 CMOS Quad 2 input NOR (might be a 4011 Quad NAND - can't read the marking)
  • 2MHz crystal
  • 6.3V zener - I had used 9V batteries for power (I probably could have run the parts directly but the typical voltage for the Pong chip is +6V to +7V)

 

The bottom of the board:  You can see the blackened wire ends wrapped on the pins.

image

 

Switches and jacks viewed from inside the case:

image

 

To verify life I thought that I'd just power it up and verify the clock circuit and that the video sync and composite outputs were working.

 

2 MHz oscillator waveform:

image

 

Video sync:

image

 

Composite video:

image

 

So looks good to proceed.  Hope to have a functioning game soon.  I just realized that I'll have to scare up a composite monitor......

Parents

  • It is encouraging to see that technology this old can still be brought back to life. I was intrigued by the wire wrap as I started in my design days using wire wrap, mainly because it didn't use a soldering iron or PCB. I made an 8088 based microcomputer using wirewrap and it worked, although sadly I no longer have it as it went to the great scrap heap in the sky when 8088s were replaced by PICs. You might struggle to find a composite monitor as most CRT based system seem to have been scrapped.

     

    Dubbie

  • in reply to dubbie

    We used to build test systems with large multi slot backplanes.  Used a lot of automation back then.  Too bad I don’t have pictures - the wire wrap machines were essentially large robots moving the wire wrap head to programmed xyz coordinates.  In the beginning it was just a pointer and the operator still did the actual wire wrapping manually.  The biggest problem we had was testing the finished systems for opens and shorts (continuity) since all the points under test needed to be contacted simultaneously.  We also had to do hi-pot testing.  Brings back a lot of memories.

     

    I remember building my first microcontroller using an 8008 on a breadboard - took over 60 discrete ICs because you had to multiplex everything out of that small 18 pin DIP .  That’s also long gone....

  • in reply to ralphjy

    Ralph,

     

    The 8008 was too early for me, as was the 8080. I started with the 8085 SDK kit when studying and moved onto the HP64000 emulator system for the 8085 when I started working. I don't remember building an 8085 board so we must have used purchased boards. I've never even seen an 8008 in real life. I did look at 4004 once I think for some reason but probably decided it was too complicated or not powerful enough.

     

    Dubbie

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  • in reply to ralphjy

    Ralph,

     

    The 8008 was too early for me, as was the 8080. I started with the 8085 SDK kit when studying and moved onto the HP64000 emulator system for the 8085 when I started working. I don't remember building an 8085 board so we must have used purchased boards. I've never even seen an 8008 in real life. I did look at 4004 once I think for some reason but probably decided it was too complicated or not powerful enough.

     

    Dubbie

Children
  • in reply to dubbie

    You're a real youngster then....  The first serious computer that I started working on was built using 74181 ALU chips and PMOS memory (negative logic back then meant negative voltage and we used a lot of voltage shifters between the memory and processing system).  I think I still have hand drawn schematics somewhere and the logic drafting templates.  I wish that I had kept some of the PCBs and parts.

  • in reply to ralphjy

    Ralph,

     

    Yes, I do remember the 74??LS181 ALU chips. I toyed with the idea of making my own computer based on them but it was on the cusp of programmable logic at the time so I looked to the future and did PLDs with my students instead. It was certainly easier.