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ADVANCED DISPLAY PROGRAMMING
This appendix describes CRT display programming with the analyzer display language.
A display program increases the CRT graphics capability of the spectrum analyzer. Explicit display programming
generally uses less display memory, allowing more efficient use of the 4,096 display addresses available.
Appendix A, Display Memory Structure, provides background material for information in this appendix.
DISPLAY PROGRAM DEFINED
A display program consists of a specific set of display commands which are followed by instructions and/or data
words written into the display memory.
Use these commands to write display programs into memory.
DA
DW
DD
DR
Instruction Words
dictate the operating mode of the CRT circuitry, such as label, graph, or plot. The
contain amplitude or position information.
Instruction and data words are written into memory when the above commands are used. For example, the code
"PA 500,600" writes into the display memory the instruction word for vector, 1026, followed by the x and y data
values 500 and 600. This same "plot absolute" command could also be done as a display program by writing
memory.
LOADING AND READING A DISPLAY PROGRAM
Instruction and data words are loaded directly into the analyzer display memory by, fist, specifying the beginning
address of the program, then writing in the instructions and data serially. To write the "1026,500,600" program
beginning at address 1024 (the first address of trace B) , execute
O U T P U T 718;"DA 1024:DW 1026,500,600;"
This program instructs the display to draw a vector to the position (500,600) on the CRT
*The first byte contains the four most significant bits, the second contains eight least significant bits of the E-bit instruction or data word.
DD must be executed for every 2 bytes input into the analyzer.
6 A p p e n d i x
Appendix B
Display Address puts the address into the display memory address register (referred to
as the current address).
Instruction or Data Write writes the instruction or data word into the current display
address. The current display address pointer is then automatically advanced to the next
higher address.
Binary Instruction or Data Word writes two &bit binary words into the current
address. *
Display Read places the contents of the current address on the HP-IB data lines. These
contents are then read by the HP-IB controller according to the current Output format
(01 to 04). Execution of each DR concludes by advancing the current address by one
APPENDIX B
data words
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