|An 8-tube module from a 1954 IBM mainframe examined|
|By Thom Holwerda on 2018-01-08 13:32:00|
IBM's vacuum tube computers of the 1950s were built from pluggable modules, each holding eight tubes and the associated components. I recently came across one of these modules so I studied its circuitry. This particular module implements five contact debouncing circuits, used to clean up input from a key or relay. When you press a key, the metal contacts tend to bounce a bit before closing, so you end up with multiple open/closed signals, rather than a nice, clean signal. The signal needs to be "debounced" to remove the extra transitions before being processed by a computer.
This is so far before my time, it basically looks like 19th century machinery to me. The steps between this module and what we have today blow my mind.
- PC-RETRO Motherboard Kit: IBM clone computer - 2018-08-13
- Why do I use the IBM Model M keyboard? - 2018-07-08
- What it's like to watch an IBM AI successfully debate humans - 2018-06-19
- New guts bring new processors, DDR4, USB3 to old ThinkPads - 2018-03-13
- More related articles