The MicroStepper operates by pulling the Z80 WAIT signal low whenever a READ or WRITE signal is detected.

When the computer operation stops it can be Reading or Writing and either to Memory or to a Port.

The current address and data are displayed on the 6 TIL311 Hex displays.

The current state of MREQ IORQ READ and WRITE is displayed by 4 LED's

The computer will stop until a flip-flop is operated – either by a push button or by the slow pulsing 2Hz clock.

Front Panel Switches

SW1  GO Push Button – This controls the Single Step process when SW2 is switched to the STEP position.

SW2  3-Pole switch – (1) BREAK, when the switch is in this position the computer can be run to any address. After setting the required address on the thumbwheels press GO to run to the address. The computer will halt and can be single stepped from this address when SW2 is switched to (2) the STEP position.

When switched to (3) RUN, the computer will run normally after GO has been pressed.

The 2Hz switch is used to run the computer very slowly, this enables any sequence of instructions to be easily monitored.

(AP)  May 2010

  MicroStepper Schematic

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