1948: valve plug-in unit and the IBM 604
IBM 604
The IBM 604 was an electronic „computer punch“. This name is based on two main aspects. On the one hand already in 1948 the IBM 604 was able to accomplish basic arithmetic operations in an electronic speed (one process of addition lasts about 370 microseconds) and on the other hand data have been saved by punching holes in perforated tape. A computer consisted of about 1400 tubes and it could be processed 60 to a maximum of 70 sub- steps within a program. Worldwide, approximately 5600 computers were installed, which in those days was a quantum leap towards commercial marketing. The input and output of data was carried out on an perforated tape. Furthermore the computer had no program memory. The IMB 604 was developed and manufactured under the direction of E. R. Palmer. To him we owe also the concept of plug- in unit, by what electronic components could be easily replaced. Each fixed computer at home uses this concept, because even today nearly all components are plugged on the motherboard.
Other features were:
- Flip- Flops for the storage of 37 points
- 13- digit calculator in BCD- coding
- Gates (AND/ OR)
- Thyratron for output to relays, control solenoids, etc.
- Switching time: 1-3 microseconds
- Cycle time: 500 microseconds
- Signal level: 100V (inactive) to 150V (active)
