Most installations used a hardcopy sign-up sheet to reserve computer
time. Typically, a user could sign up for a block of time in multiples of a
half hour or so. A user might sign up for an hour and finish in 45 minutes; this
would result in wasted computer processing time. On the other hand, the user
might run into problems, not finish in the allotted time, and be forced to stop
before resolving the problem.