|CHARACTER||DISPLAY CODE||CURRENT STARTING LOCATION IN RAM|
Remember that we only took the first 64 characters. Something else will have to be done if you want one of the other characters.
What if you wanted character number 154, a reversed Z? Well, you could make it yourself, by reversing a Z, or you could copy the set of reversed characters from the ROM, or just take the one character you want from ROM and replace one of the characters you have in RAM that you don't need.
Suppose you decide that you won't need the > sign. Let's replace the > sign with the reversed Z. Type this:
FOR I=0 TO 7:POKE 12784+I,255-PEEK(I+12496):NEXT
Now type a > sign. It comes up as a reversed Z. No matter how many times you type the >, it comes out as a reversed Z. (This change is really an illusion. Though the > sign looks like a reversed Z, it still acts like a > in a program. Try something that needs a > sign. It will still work fine, only it will look strange.)
A quick review: You can now copy characters from ROM into RAM. You can even pick and choose only the ones you want. There's only one step left in programmable characters (the best step!)... making your own characters.
Remember how characters are stored in ROM? Each character is stored as a group of eight bytes. The bit patterns of the bytes directly control the character. If you arrange 8 bytes, one on top of another, and write out each byte as eight binary digits, it forms an eight by eight matrix, looking like the characters. When a bit is a one, there is a dot at that location. When a bit is a zero, there is a space at that location. When creating your own characters, you set up the same kind of table in memory. Type NEW and then type this program:
10 FOR I=12448 TO 12455: READ A:POKE I,A:NEXT 20 DATA 60, 66, 165, 129, 165, 153, 66, 60
|This page has been created by Sami Rautiainen.|
|Read the small print.||Last updated December 23, 2002.|