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LD-V8000 Level II • Chapter Two
2.5.2 Commands
The Level II command set represents the functions available for development of a
Level II program. Many of the commands are direct counterparts of buttons on the
RCU (e.g., SEARCH, AUDIO1, DISPLAY, etc.) and they cause corresponding
operations to be performed by the player. Other commands are used for
controlling program interpretation, directing the path of execution, managing
registers, etc. A command is stored as a one-byte code in the active memory.
Any argument must be placed before the command. An argument, if any, and the
following command make an instruction. See Chapter 4, Level II Commands for
the LD-V8000, for a description of each Level II comma
Refer also to Appendix
nd.
B, Alphabetical Listing of Level II Commands Available on the LD-V8000.
Many commands can be executed directly by the player or entered into RAM from
the RCU with a single button press. All codes and any data byte can be entered
into RAM as a hexadecimal code, with three button presses on the RCU. See the
procedure described in Section 3.1.3, Entering Level II Code with the RCU.
When the programmer enters arguments, commands, and data from the RCU, the
video display shows the byte codes on-screen as command or digit mnemonics
whenever possible. Unrecognized codes are displayed as two-character hex values.
2.5.3 Program Structure
A Level II program segment, when stored in memory, is a continuous string of one-
byte codes. The string is processed by the player's Level II program interpreter
beginning at the location specified or implied by the RUN command. As each byte
is examined, argument codes are accumulated until an executable command code
is found. Some commands have explicit arguments, others have implied
arguments, default arguments, or no arguments.
As an example, the two instructions 1000 SC 2000 AS are internally represented
as codes 0F, 3F, 3F, 3F, F7, 8F, 3F, 3F, 3F, F3. Starting with the first byte, 0F, the
argument is accumulated while the codes are scanned for a command code. In
this example, the Search command code, F7, is detected. The SC command, using
the currently accumulated argument (0F, 3F, 3F, 3F), instructs the player to
position the laser read head at frame 1000.
When the player is executing Level II program code (in Automatic Mode), succeeding
commands from memory are not processed until the function specified by the
"current" command has been completed. The Play command and the INN command
are the exceptions. A Play command instructs the videodisc player to begin playing
audio-video material and continue until instructed to do something else by another
command.
Pioneer LD-V8000 Level II User's Manual
2-15
TP 114 v. 1.1
•
8/92
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