A CALL to PEEK and POKE
By Grant Kwai
Copyright (c) 1991 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.


Over the past several months, I have been writing various articles on some of the many PEEKs, POKEs, and CALLs you can implement on the Apple //. Here are a few more which you can try on your Apple // computer.

PEEK(-16384)   :Last key entered.
POKE -16368,0  :Clears the Keyboard Strobe.
POKE 48,x      :Sets colours for low res graphics.
POKE 50,255    :Sets text display to NORMAL.
POKE 50,63     :Sets text display to INVERSE.
POKE 50,127    :Sets text display to FLASH.
POKE 50,x      :Try it, and see what you get!
CALL -167      :Enter the monitor and reset.
CALL -259      :Read from a tape.
CALL -458      :Verify.
CALL -657      :Allow input of colons and commas.
CALL -912      :Scroll one line.
CALL -922      :Carriage return.
CALL -1002     :Moves the cursor left one position.
CALL -1036     :Moves the cursor right one position.
CALL -1233     :TEXT

These are for Dos 3.3 and will not work under ProDOS:

CALL 42350     :Catalog the disk in the disk drive.
POKE 44793,11  :Prevents normal save of dos.
PEEK(46063)    :Returns number of tracks DOS 3.3 is using (normally 35)

Below is a way of figuring out what type of error you have. You might like to implement it in one of your programs, to make it more 'user friendly'.

PEEK(222)      :This will return a number, which is in fact the code number for an error in an ONERR message.

Number:   Meaning:
0     NEXT without FOR
1     Language not available
2,3   Range error
4     Write protected
5     End of Data
6     File not found
7     Volume Mismatch
8     I/O error
9     Disk full
10    Locked file
11    DOS syntax error
12    No buffers available
13    File type mismatch
14    Program too large
15    Not direct command
16    BASIC syntax error
22    RETURN Without GOSUB error
42    BASIC out of DATA
53    Illegal quantity
69    Overflow error
77    Out of memory
90    Undefined statement
107   Bad subscript
120   Redimensioned array
133   Division by Zero
163   Type mismatch
176   String too long
191   Formula too complex
224   Undefined function
254   Bad input response
255   Control-C break

If there are any AUG members who may have missed out on my previous PEEKS, POKES and CALL articles and would like a copy, you can obtain a copy directly from me by sending a disk (Apple 5.25" only, or IBM 5.25" or 3.5") in a postpack, making sure you include return postage. I will then copy the files to your disk and return it as soon as possible. Write to me at PO Box 74, Telopea NSW 2117.

THIS CONTENT COPYRIGHT © 2007, APPLE MACINTOSH USERS' GROUP, SYDNEY
Permission has been obtained to make this material available on the Internet.

Permission is hereby granted for non-profit user groups to republish this content.
PLEASE CREDIT THE AUTHOR AND THE SOURCE: Applecations, publication of the Apple Users' Group, Sydney, Australia

THIS PAGE COPYRIGHT © 2007, ANDREW ROUGHAN