HD6475368CP Datasheet, PDF (25/108 Pages) Agilent(Hewlett-Packard) – H8/536 Emulator PC Interface

Initialization
The program instruction at the Init label initializes the stack pointer.
Reading Input
The instruction at the Read_Cmd label clears any random data or
previous commands from the Cmd_Input byte. The Scan loop
continually reads the Cmd_Input byte to see if a command is entered
(a value other than 0 hex).
Processing Commands
When a command is entered, the instructions from Exe_Cmd to
Cmd_A determine whether the command was "A", "B", or an invalid
command.
If the command input byte is "A" (ASCII 41 hex), execution is
transferred to the instructions at Cmd_A.
If the command input byte is "B" (ASCII 42 hex), execution is
transferred to the instructions at Cmd_B.
If the command input byte is neither "A" nor "B", an invalid command
has been entered, and execution is transferred to the instructions at
Cmd_I.
The instructions at Cmd_A, Cmd_B, and Cmd_I each load register R1
with the length of the message to be displayed and register R4 with the
starting location of the appropriate message. Then, execution transfers
to Write_Msg which writes the appropriate message to the destination
location, Msg_Dest.
After the message is written, the instructions at Fill_Dest fill the
remaining destination locations with zeros. (The entire destination area
is 20 hex bytes long.) Then, the program branches back to read the
next command.
Getting Started 2-27