All good. Dos is fine as I can dedicate a spare comp to running just the prog. CPU usage doesn't matter. I have wired the interface and it's all set to go. I am using a 1300E sensitive reed-relay in series with a led which closes from RTS to Pin 5. That works fine, you couldn't get a more simple interface.
Can you program it for six timers? This will give me room to add some extra commands I've always needed.
Having the displays read h:m:s lets me know at a glance how long I have to go in real time on the longest periods.
Parallel operation is ok, it's just means that if want to, say, shorten the duration of Timer 2, then I have to shorten the following timers T3, T4 etc by the same amount.
I think this will make more sense when I explain that with each timer, the countdown is always progressively longer e.g T1 3m 18s, T2 7m 56s, T3 1h 30m 45s, T4 1h 47m 34s etc. Obviously then sequencing the timers, and altering only one, avoids having to also alter the others. (Individual periods would be entered for each one, as opposed to running-totals when in operating in parallel).
Anyway, I'm happy to give your updated ver a whirl. I'll check in later . Thanks again.