
1. COMMON OPERATIONS
FOR THE PC9801 AND IBM PG’AT
1 .1.3 Protocol
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When the FLOAD98 or FLOADAT command is executed on the PC side, a communications
request is issued for the P-G and reception begins.
After all data has been received, DC 3 is
sent and transmission is completed.
0 DC 1 code is sent to the P-G (data transmission request).
8 Data is received.
Q Completion code is received and reception is completed.
@ DC 3 code is sent.
Transmission and reception both use the l-byte machine-dependent
output.
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BIOS call for input and
After the P-G issues a transmission request, the P-G enters the waiting state. FLOAD98 or
FLOADAT is activated in the PC, then transmission begins. After all data has been sent. DC 4
is sent and transmission is completed.
0 The P-G issues DC 1.
8 DC 2 code is sent to the P-G.
@ Data is sent.
@ DC 4 code is sent.
Transmission and reception both use the l-byte machine-dependent
output.
1.1.4 BUSY control
BIOS call for input and
When the transmission speed is faster than reception processing, BUSY control is performed by
issuing the DC 1 and DC 3 codes. In the PC9801 series, the X parameter in the DOS SPEED
command is set to off, which allows the application to provide support for BUSY control. In the
IBM PC/AT series, there is no X parameter, which effectively has the same result.
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