IA8044/IA8344
SDLC COMMUNICATIONS CONTROLLER
Data Sheet
station. If the response is positive the SIU interrupts the CPU. If the response is negative the SIU
retransmits the frame. The SIU can send the following responses to the primary station.
RR (Receive Ready),
RNR (Receive Not Ready).
The FLEXIBLE mode requires the CPU to control the SIU for both transmitting and receiving.
This slows response time but allows full SDLC and limited HDLC compatibility as well as
variations. In FLEXIBLE mode the SIU can act as a primary station. The SIU will interrupt the
CPU after completion of a transmission without waiting for a positive acknowledgement from the
receiving station.
Basic SDLC Frame
FLAG
ADDRESS
CONTROL
INFORMATION
FCS
FLAG
IA8X44 Frame parameters:
Flag
Address
Control
- 8 bits
- 8 bits
- 8 bits
Information - n bytes (where n £ 192)
FCS
Flag
- 16 bits
- 8 bits
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ENG210010112-00
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