Atari XL Super POKEs
I read in an earlier issue of COMPUTE! that some Atari owners do not like the audible keyboard feedback (keyboard click). You can always turn down the volume, but this prevents you from hearing any other sound effects. This simple POKE will turn off the keyboard click: POKE 731,1. POKE it with a zero to turn the click back on.
This POKE works only on the new XL Atari models, not on the original 400/800 computers. There is no easy software solution for the 400/800, but this POKE works fine on the 1200XL, 600XL, and 800XL. There are many other useful POKEs on the XL computers. Remember that none of these POKEs will work with the older 400/800 computers, so if you are writing programs for publication or sharing, keep this in mind.
First try this one: POKE 622,255:GRAPHICS 0. This allows fine scrolling of GRAPHICS 0 screens. Instead of jumping up a line at a time, the screen will smoothly scroll 1/8 character at a time. Use POKE 622,0:GRAPHICS 0 to reset the scroll. You must always follow this POKE with GRAPHICS 0.
POKE 756,204 enables the built-in international character set. Hold down CTRL and press some of the letters of the alphabet to see these new characters. Use POKE 756,224 to go back to the normal character set with the graphics characters. POKE 621,255 disables the keyboard, and POKE 621,0 reenables it. SYSTEM RESET will get you out of this mode if it gets you into trouble. You can read the HELP key with PEEK(732). Location 732 returns a 17 when the HELP key has been pressed. You must POKE it with a 0 to clear it out after you've acted on the key. SHIFT and CTRL also affect the HELP key, returning 81 and 145, respectively.
All keys begin to repeat when you hold them down. To change the delay before the key begins to repeat, POKE 729 with the number of 1/60 seconds you want to delay. A value of 30 would be a half-second delay. The default is 48, or 4/5 second. A POKE to 730 controls how quickly a key repeats once the repeat has begun. The delay between repeats is also measured in 1/60 seconds. The default here is about 1/10 second.
If you want to take advantage of XL features, yet permit the program to run on the 400/800, you can check the operating system ID byte, found at location 65527 in ROM. There is a different number for every version of the Atari operating system. If this byte returns a value for the 400/800, you can skip over the statements specific to XL models. Consult COMPUTE! Books' Mapping the Atari for a comprehensive guide to Atari memory, and the article "An Introduction to Atari PEEKs and POKEs" in The Atari Collection, Volume 1, due to be released in a few weeks.
|400/800 Revision A||221, 87, or 243|
|400/800 Revision B||230|
|1200XL Revision A||10|
|1200XL Revision B||11|