Commodore 128 Programmer's Reference Manual page 424

414 COMMODORE 128
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split screen our code throws off the timing, making for an unattractive display. ^
There are really only three things to watch out for when toying with the C128
system IRQ: First, be sure to keep the raster compare value on-screen to keep the \ j
IRQ's happening (the best way is to keep RC8 zero as in example above); second, LJ
never attempt to access the 8563 during an IRQ if there is any chance that it is in
use; finally, be sure the source of the IRQ is being cleared. ,
CBM STANDARD KERNAL CALLS y
The following system calls make up the set of standard CBM system calls for the
Commodore 128 Personal Computer. Several of the calls, however, function somewhat j j
differently or may require slightly different setups than C64 mode. This was necessary [j
to accommodate specific features of the system, notably the 40/80 column windowing
Editor and banked memory facilities. As with all Kernal calls, the system configuration
(high ROM, RAM-0 and I/O) must be in context at the time of the call. |
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1. $FF81 CINT initialize screen editor and devices /
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PREPARATION:
Registers:
Memory:
Hags:
Calls:
RESULTS:
Registers:
Memory:
Flags:
EXAMPLE:
SEI
JSR $FF81
CLI
none
system map
none
none
.A used
.X used
.Y used
init Editor RAM
init Editor I/O
none
;initialize screen
CINT is the Editor's initialization routine. Both 40- and 80-column display j >
modes are prepared, editor indirect vectors installed, programmable key definitions
assigned, and the 4 0 / 8 0 key scanned for default display determination. CINT
sets the VIC bank and VIC nybble bank, enables the character ROM, resets SID 1 [
volume, places both 40- and 80-column screens and clears them. The only thing it LJ