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APPENDIX B
clear x position (clx) :
big expand (hex) :
expand and shift (exs) :
(dim):
dim
(brt) :
bright
Flow-of-Control Instruction Words.
ory starting with address PI and working one address at a time to address 4095. Flow-of-control instruction words
alter the normal flow of a refresh program by allowing program execution to be transferred anywhere in memory.
They allow jumps to specific display addresses (imp), jumps to a display program subroutine (jsb), returns (ret),
skips to the next control instruction (skc), and a word that simulates a "for...next" loop, the decrement-and-skip-
on-zero (dsz). Control instructions contain pI 1 P, in bits 11, 10, and 9, respectively.
jump to subroutine (jsb)
return (ret)
skip to next control instruction (skc)
skip to next memory page (skp)
end of display (end)
decrement and skip on zero (dsz)
The address to be jumped to is the contents of the memory word following the jmp or jsb instruction. For example,
causes
program execution to jump to address 2048. The address given should contain a control
instruction. (If the address does not contain a control instruction, the program will go to the first control instruction
following the specified address.) A return (ret) causes the program execution to return to the first control instruction
following the jsb instruction that sent it to the subroutine.
'The display size commands combine these size instructions as follows:
D2
D 3
is slowed.
Reset the x axis display position to the far left (0,~).
Amplify the x and y CRT beam deflection by a 1.9 factor. 1
Amplify the x and y CRT beam deflection by a 1.13 factor (expand) and shifts the
Set the CRT beam intensity below the normal level.2
Set the CRT beam intensity to the maximum level.*
The CRT refresh program normally executes the contents of mem-
instructions
none
bex and exs
ADVANCED DISPLAY PROGRAMMING
8
7
6
54
3
2
origin shifted
ratio to D 1
1.00
1.13
1.68
1.49
10
1035
1227
1027
no
no
writing
rate
A p p e n d i x 9
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