6100 ADCCP Programming Manual

6100 ADCCP Concepts and Context
Introduction to 6100 ADCCP
069225 Tandem Computers Incorporated 1–7
Asynchronous Response Mode (ARM)
In ARM, a secondary station may transmit data whenever it is ready; no poll is
required from the primary station. The primary station is responsible for setting up
and dissolving the link; otherwise, the stations function essentially as peers. Figure 1-3
shows ARM.
In Figure 1-3, the primary station issues a SARM to set up the line. The secondary
station responds with a UA. Stations exchange information without a need for polling.
Two-way alternate and two-way simultaneous operation is supported.
Figure 1-3. ARM Line-Control Mode
Primary Station
Secondary
Station
SARM
UA
Primary Station
Secondary
Station
I
I
022
Asynchronous Balanced Mode (ABM)
In ABM , two combined stations communicate on a point-to-point link. Either or both
stations issue commands to set up or dissolve the link. (There is no harm in having
both stations issue the commands in parallel; there is also no advantage.) During data
transmission, also, the stations function as peers. Figure 1-4 shows ABM.