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ADVANCED DISPLAY PROGRAMMING
Subroutines must not contain label or graph control words. A subroutine may not call
another subroutine.
The skip-to-next control instruction (skc) causes program execution to go to the next instruction in memory The
skip-to-next page (skp) instruction causes program execution to go to the next address that is an integer multiple of
1024. (An instruction that combines skp and skc, 1056 + 3 = 1059, executes as if it were a skp followed by a
The decrement and skip-on-zero (dsz) instruction decrements an internal count register then tests the contents for
zero. If the contents are not zero, the program goes to the next control instruction. If the contents equal zero, the
program will skip the next two addresses then go the next control instruction. For example, "1099, 1035, 1532,
1026" causes the program to skip to the control word 1026 if the counter register is zero; otherwise it executes the
1035, 1532, which is a jump to address 1532. See Load Counter and Threshold Instructions below.
The auxiliary control function clear x position (clx) can be added to any of the program control instructions.
Another method of causing skips in program execution is with the label mode (either LB or lbl). This is discussed
under Data Words.
End of Display Instruction.
display program. The next execution of the program then begins at display address zero on the next display refresh
trigger (note that refresh trigger and sweep trigger are not the same).
The end of display instruction bit supersedes all other coding in the instruction except the auxiliary function clear x
position, clx (bit 4)) which may be added. The end instruction causes a default-to-graph mode at the beginning of
the next program execution if no display control instruction is at address zero.
Since fast sweeps (direct display of video and sweep for sweep times less than 20 msec) are displayed between
program executions, an end instruction is required for proper operation of the fast sweep display.
An end-of-display in trace C is changed to a skip-to-next memory page, 1056, when a B s C exchange is
executed.
Load-Counter and Load-Threshold Instructions.
register with a value determined by bits fJ through 8 of the instruction. The internal register is used in either of two
ways. In the graph (gra) mode, the display program interprets the register contents as the display THRESHOLD
1 0 A p p e n d i x
NOTE
When executed, the end of display instruction terminates execution of the
The load-counter instruction loads an internal count
APPENDIX B
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