Extension for the simulation of some interface circuits

There are currently 3 simulators of external circuits which have been developed: 6821 (PIA parallel interface), 6840 (PTM timer), 68230 (PI/T parallel interface and timer). These circuits are currently interfaced with 8-bits ADC, LED displays and a switch.

Interface circuits 6821, 6840, LED and ADC

This window is in 2 parts (see figure 4) :

• On the left side, one can see a 6821, an ADC which you can manually adjust the value with a slider and 3 LED display

• On the right side, one can see a 6840 timer

Figure 4: 6821/6840 simulators

The 6821 is used to read input from the ADC and display the value on the 3 LED.

The clock of the timer is independant from the one of the microprocessor and can be stopped and started with the ``Stop'' / ``Start'' button associated to each counter. There is a scale to tune the speed of each counter. The ``Step'' button decreases the counter of 1. Note that the counter will keep on running even when you stop the 680x0 simulator, as the clock is independant.

Interface circuits 68230, LED, 2 ADC and SWITCH

This window is in 2 parts (see figure 5) :

• On the left side, one can see the registers of the 68230 corresponding to the Parallel Interface

• On the right side, one can see the registers of the 68230 corresponding to the Timer at the bottom, 2 ADCs which you can manually adjust the values with sliders, a SWITCH with two lights (green/red) indicating which canal is selected, and 3 LED display

Figure 5: 68230 simulator

The 68230 is usually used to read input data from one of the ADC and then displays the value on the 3 LED. The switch commute from one ADC to the other. It is not electronic, that is it is a software activated switch and must be driven from the program.

The timer part is currently not implemented yet and therefore not functional