Originally, Malvino and Brown presented the SAP-1 architecture in a book called Digital Computer Electronics. The design gained massive popularity when it was build as a bread board computer by Ben Eater on a series of YouTube videos. The architecture contains various modules, including the instruction execution set gives the SAP-1 a total of six stages from 0 to 5, repeating all over again.
The more important module is the controller. It controlls the assertion execution according to the stimuli from the stages. The stages 3 to 5 five depend on the instructions of the operation codes.
Design Output Reading Section The design is engineered to read the output signal generated from the bus, which contains the information of the add and subtract operations executed by the design. Currently, the only method to read the signals is through an oscilloscope. However, a significant enhancement would be the implementation of a state machine controlling a 3 7-segment display to show the numbers on the 8-bit bus (up to 255).
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | n/a | bus[0] | n/a |
| 1 | n/a | bus[1] | n/a |
| 2 | n/a | bus[2] | n/a |
| 3 | n/a | bus[3] | n/a |
| 4 | n/a | bus[4] | n/a |
| 5 | n/a | bus[5] | n/a |
| 6 | n/a | bus[6] | n/a |
| 7 | n/a | bus[7] | n/a |