>>                 repeat
>>                     if overflow then
>>                         begin
>>                         hi := hi + 1;
>>                         clear overflow
>>                         end{if};
>>                     lo := timer
>>                 until not overflow
>
>Or just
>
>        lo = timer
>        if (overflow) {
>            lo = timer
>            ++hi
>            clear overflow
>        }
>
>I think this will save one instruction, and seems a trifle clearer.

        This is just unrolling the loop once.  The number of
        instructions is the same (you save a test on "overflow"
        but add a "lo = timer").

        I prefer the looped version because it handles the
        situation where the timer overflows immediately after
        you've cleared overflow.

        This seems a trifle more robust to me.  It also more
        closely matches what I intuitively expect the code to
        do, which is to tell me the current 'time'.

___Bob