Commodore Computer C16 Instrukcja Użytkownika Pobierz pdf (Strona 9)

READING THE KEYBOARD

The easiest way to read the keyboard from Basic is to use the GET or GETKEY

commands. Here is a third way: PEEK(198). The computer checks the keyboard every

60th of a second and stores a value corresponding to the key pressed at memory

location 198. The stored value is a bit pattern of the keyboard matrix, not a PET-

ASCII or screen value of the key. Below is a list of all the values. For example,

if you like to test the F1 key: IF PEEK(198)=4 THEN...

=================================================

Key Value Key Value

=================================================

Esc 52 Run/Stop No Effect

1 56 Shift Lock No Effect

2 59 a 10

3 8 s 13

4 11 d 18

5 16 f 21

6 19 g 26

7 24 h 29

8 27 j 34

9 32 k 37

Left Arrow 48 l 42

Right Arrow 51 : 45

Up Arrow 43 ; 50

Down Arrow 40 * 49

Inst/Del 0 Return 1

-------------------------------------------------

Ctrl No Effect Commodore No Effect

q 62 Left Shift No Effect

w 9 z 12

e 14 x 23

r 17 c 20

t 22 v 31

y 25 b 28

u 30 n 34

i 33 m 36

o 38 , 47

p 41 . 44

@ 7 / 55

+ 54 Right Shift No Effect

- 46 £ 2

Clear/Home 57 = 53

-------------------------------------------------

F1 4 Space 60

F2 5 No key 64

F3 6

Help 3

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LIMITING THE BASIC MEMORY

LET'S START WITH THE END

Basic programs use the free memory while running. If you have stored your own

machine language programs into the memory or your own character set, you have to

inform Basic not to use that area of memory, or otherwise Basic will overwrite

your machine language programs or your character set with temporary data.

To protect your machine language programs and/or your custom character set, the

easiest way is to place them at the end of the memory and to inform Basic that the

memory available for Basic ends right before your machine language programs and/or

custom character set begins.

The highest address of Basic memory can be read and set through memory

locations 55 and 56. Location 55 contains the lower 8 bits of the address and 56

the upper 8 bits.

To read the current "Top of Basic memory" (=end position), type the following line

in Basic and press Return:

PRINT PEEK(55) + PEEK(56) * 256

To protect your machine language programs and/or custom character set, follow

1 2 3 4 5 6 7 8 9 10 11 12 13 14

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