HP -01 Owner's Manual page 93

Timer/Stopwatch Register. The timer and stopwatch functions are handled in a register that
holds hours, minutes, seconds, and hundredths of seconds (HH:MM:SS.CC). Because there is
not room to display all eight digits, you see only three out of the four time fields. If the time is
greater than or equal to an hour, HH:MM:SS is displayed. If the time is less than an hour,the last
three fields are displayed as MM:SS.CC.
The time interval loaded into the register determines the function. If zero is in the register, your
HP-01 is set to count up or increase (stopwatch). A time other than zero sets the register to
decrease or count down (timer).
© starts and stops the timer/stopwatch. When the timer/stopwatch is running, the contents of
the register are updated every 0.01 seconds. The largest timer time interval allowed is 99:59:59.
The stopwatch counts up to 23:59:59.99, then rolls over to zero.
Memory Register. The memory will accept any type of data and retain it until it is replaced with
new data.
Operational Description 91