For the program input of the microcomputer eight (8) tumble switches are available on the service-panel. Every 8 bits dataword must be adjusted with each of these switches. Not so easy to do. For instance the DELAY instruction consists of two 8-bit words, 8F (Hexadecimal) and FF H.
To simplify these tumble switch actions, the "Running lights" program , a simple one, consists of sixteen (16) 8-bit words, the SC//MP microcomputer was extended with a keyboard. This keyboard contains push-buttons from 0 to F Hex and a data (LOAD-DATA) push-button. This data key exports the data (2 digits) build up with two actions of the numbered keys to the microcomputer. So a complete 8 bits dataword can be build and transported by three actions instead of nine ones.
Below the electrical setup of this keyboard with the used CMOS-chips (low power-consuming) can be fetched.
Also a color-picture of the Microcomputer with keyboard is given.
Remark : These days the microcomputer with connected keyboard is still operating very well !
Images of the electrical keyboard-diagram (full sizes 11KB and 10KB)
