Commodore VIC-20 - Page 62

48 The VIC 20 User Guide
computer to look for the file named, skipping any others it finds.
After a program
is loaded from tape, you can leave the PLAY key
depressed if you will be loading more information from the tape
at a later
time. However, if you do not intend
to load another program from tape
soon, it
is a good idea to press STOP to release the PLAY key so you will not
accidently try to SAVE a program while the Datassette
is in the play mode.
The VIC can detect when a Datassette key has been pressed, but it cannot
distinguish which key was pressed. Therefore, if
PLAY and RECORD are
pressed (to SAVE a program) and you attempt
to LOAD, the Datassette
will erase the program instead of reading it.
You may occasionally have trouble loading a program from tape.
Instead of displaying
READY.
the VIC may display the following message:
?LOAD
ERROR
READY •
•
If this happens, rewind the tape and try loading it again. Try this several
times if necessary.
If this does not work, there may have been an undetected
problem when the program was saved. Always VERIFY programs after you
SA
VE them, and if they are important or have taken considerable time to
enter, make one
or more backup copies.
One way to reduce errors during the SA VE procedure
is to fast-forward
a new tape to the end, then rewind it
to the beginning before storing anything
on it. This winding and rewinding process will tend
to make the tape move
through the tape mechanism more smoothly. This
is because when tapes are
manufactured they are wound onto their spools
at high speed. This process
often puts some tension on the tape, and the first time it
is unwound it may
jump a bit as it moves through the mechanism.
It may also pull and stick
slightly in the cassette. Although these effects are not usually noticeable in
audio applications, they can cause data errors on computer tapes.
Before entering a LOAD instruction, be sure
to rewind the tape to a
point before your program begins; otherwise the VIC will never find it. A
good practice
is to note the number of the tape counter at the beginning of
your program and write it down on the tape label beside the name of the