prindle@NADC.ARPA@sri-unix.UUCP (08/23/84)
Beware, Commodore in no way guarantees SYS(59626) will scroll the screen up one line on all past, present, and future models of the 64. Only the official Kernel vectors, as documented in the Reference Guide, are completely safe. For example, the safe way to scroll the screen is to use the PLOT Kernel call to position the cursor on line 24, then use the CHROUT Kernel call to write a CARRIAGE RETURN or CURSOR DOWN to the screen (followed by a PLOT call to put the cursor back where you want it, if not on line 24). This may seem a lot tougher than a single call, but standard interfaces exist for a reason. On the bright side, the non-standard calls will "probably" work; Commodore has so far only made changes to the Kernel by patching. But with all the cloak- and-dagger going on right now with Commodore vs. Atari, who knows what the future holds?