System information

Console Commands
VAX 4000 Model 108 User Information
A-29
byte of received data_checksum. The data is verified by adding all
data characters and the checksum character into an 8-bit register
initially set to zero. If the final content of the register is nonzero,
the data or checksum is in error, and the console responds with an
error message.
If the command is a binary unload (bit 31 of the count is set), the
console responds with the input prompt (>>>), followed by the
specified number of bytes of binary data. As each byte is sent, it is
added to a checksum register initially set to zero. At the end of the
transmission, the two's complement of the low byte of the register
is sent.
{data_checksum}\
If the data_checksum is incorrect on a load, or if memory or line
errors occur during the transmission of data, the entire transmission
is completed, and the console issues an error message. If an error
occurs during loading, the contents of the memory being loaded are
unpredictable.)
The console represses echo while it is receiving the data string and checksums. The
console terminates all flow control when it receives the carriage return at the end of the
command line to avoid treating flow control characters from the terminal as valid
command line checksums.
Controlling the Console Serial Line
You can control the console serial line during a binary unload using the control keys
(Ctrl/C, Ctrl/S, Ctrl/O, and so on). You cannot control the console serial line during a
binary load, because all received characters are valid binary data. The console has the
following timing requirements:
•
It must receive data being loaded with a binary load command at a rate of at least 1
byte every 60 seconds.
•
It must receive the command checksum that precedes the data within 60 seconds of
the carriage return that terminates the command line.
•
It must receive the data checksum within 60 seconds of the last data byte.
If any of these timing requirements are not met, then the console aborts the transmission
by issuing an error message and returning to the console prompt. The entire command,
including the checksum, can be sent to the console as a single burst of characters at the
specified character rate of the console serial line. The console is able to receive at least 4K
bytes of data in a single X command.