CCl!MUNICATIONS SECTION 6.5
6.5.3.1 Transmission
6.5.3.2
VER.V09F
When transmitting, HUNTER writes the characters into a buffer.
If the buffer becomes full, then the user program (BASIC or
CP/M) is held up until the characters or block are sent.
If a 'communication failure' is detected, execution of the user
program will be suspended until manually overridden.
Receiving
When receiving characters, data rece1v1ng commands (LINCHR and
LINPUT in Basic) will fetch any characters or blocks currently
held in the reception buffer.
NOTE: This data may have been received prior to execution of the
input command
If data is already in the buffer, then it will be returned
immediately. If no data is present, HUNTER will wait for
incoming data, and will return when characters or blocks are
available.
Reception of data is completely transparent to the user Basic
program being run by HUNTER. Data may be sent at any time to
HUNTER, communications protocols being implemented as selected.
Use is made of a
256 character input buffer. Received
characters are placed into the buffer in a 'barrel' fashion. If
more characters are received than this, without any being read
by a calling program then the earliest characters are
overwritten. This is true even if RTS or XON/XOFF handshaking
is used and is ignored by the sending device.
The effect of this buffering is to permit reception of
characters to carry on steadily through calling programs which
process the characters intermittently. This can give a greater
overall throughput.
The buffer is needed by definition for the XON/XOFF and ETX/ACK
protocols.
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