Commodore CBM - Buffer

BUFFER
The PET has a 10-character keyboard buffer to hold the ASCII code
equivalents of characters whose keys are pressed at the keyboard. This
is nor-
mally of no concern to vou.
but vou should be aware of how the buffer operates
for when vou are programming
PET inputs.
To illustrate. load the final saved version of the BLANKET program (from
Chapter
3) and press a key for display. While the display is occurring. press up to
ten more keys, then sit back and relax. Each of the keyed-in characters
will be
fetched, in turn, and displayed by the BLANKET program.
Let's look at this process in more detai!.
Whenever vou press.
say, the A key, it goes into the first storage location in
the 1O-character keyboard buffer:
Keyboard
Buffer
1
A
2
3
4
5
6
7
8
9
10
The PET keeps track of the number of characters in the buffer and the location of
the next character ta
be displayed. When GET fetches this character. a pointer is
changed ta indicate that this character has been fetched:
Keyboard
Buffer
-------.1 A
2
3
4
5
6
7
8
9
10
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