Module basic::___Appendix_A

Conversions and Compatibility

64K BASIC is the classic experience of 8-bit BASIC on a modern terminal. Part of that experience was a slightly different version of BASIC for each model of computer. BASIC was usually on ROM which wasn't trivial to update like modern storage, so you were stuck with the same version for the entire life of the computer. So instead of keeping your compiler up to date as we do today, you would know how to adjust programs written on another platform. Most books with program listings would include a page or two about the dialect the code was written for. This is that page.

RANDOMIZE X

Old computers often didn't have useful entropy, not even a real-time clock. Many implementations would reset the random number generator to the same state on ever run, but almost all would reset to the same state every boot. RANDOMIZE was used to get around this by asking the user for a seed. 64K BASIC reseeds the random number generator with good entropy on every run, so in most cases you simply delete the unneeded code.

RANDOMIZE without an X will prompt the user for a seed value. This allowed someone to replay the same game if they wanted. To emulate this behavior, here's a replacement.

INPUT "Random Number Seed";A:RND=RND(-ABS(A))

Probably the most common way to seed the random number generator is to time how long it takes the user to respond to a prompt. This is not necessary in 64K BASIC so if you see something similar to the following, you can delete it.

PRINT "Press any key to continue";:WHILE INKEY$="":RND=RND():WEND:PRINT

GET A$

To get a single keypress and store it in A$, 64K BASIC uses the newer style:

A$ = INKEY$

LOCATE ROW,COL

This is probably a GW-BASIC program so it might use graphics and sound. However, in many cases it is simply used to center text on the screen. Use STRING$ to get a bunch of newlines and SPC(X) to move to the column.

REM CLS:LOCATE 5,20:PRINT "TITLE"
CLS:PRINT STRING$(5,10)SPC(20)"TITLE"

SOUND and BEEP

64K BASIC does not support sound. Your terminal might with:

PRINT CHR$(7)