Multiple Systems Coupling device-dependent module
A Multiple Systems Coupling (MSC) device-dependent module performs all of the functions unique to a type of link.
The functions the device-dependent module performs at
each entry point are:
- DDM entry point
- MSC
- DM01
- Setup output buffer for a write or send operation
- DM02
- Error check last output operation
- DM03
- Setup to obtain input from the link
- DM04
- Error check an input operation
- DM05
- Not used
- DM06
- Not used
- DM07
- Connect or disconnect the link
- DM0I
- An access method is entered from the device-dependent module
Several entry points are not used to preserve a commonality between coupling communication and terminal communication functions.
The following table summarizes the MSC communication task trace.
| Traced by | Entry point | Function | Trace indent |
|---|---|---|---|
| DFSCMS00 | DFSCMA01 | Process Input | AM01 |
| DFSCMS00 | DFSCMA02 | AM02 | |
| DFSCMS00 | DFSCMA03 | What's Next? | AM03 |
| DFSCMS00 | DFSCMA05 | AM05 | |
| DFSCMS00 | DFSCMA06 | After Good Write | AM06 |
| DFSCMS00 | DFSCMA08 | Wash Message | AM08 |
| DFSCMS00 | DFSCMA09 | Generate Message | AM09 |
| DFSCMS00 | DFSCIO10 | Quiesce Link | AM10 |
| DFSCMS00 | DFSCIO12 | Wait for I/O or Message Enqueue | AM12 |
| DFSCMS00 | DFSCIOC0 | Get Work Buffer | CM00 |
| DFSCMS00 | DFSCIOC0 | Reposition Queue Buffer | CM01 |
| DFSCMS00 | DFSCIOC0 | Get Next | CM02 |
| DFSCMS00 | DFSCIOC0 | Dequeue Message | CM03 |
| DFSCMS00 | DFSCIOC0 | Wash Output | CM04 |
| DFSCMS00 | DFSCIOC0 | Find Output | CM05 |
| DFSCMS00 | DFSCIOC0 | Get New Output | CM06 |
| DFSCMS00 | DFSCIOC0 | Free Input Queue Buffer | CM07 |
| DFSCMS00 | DFSCIOC0 | Free Work Buffer | CM08 |
| DFSCMS80 | DFSCMS80 | Abort Processing (First LTB) | MSS1 |
| DFSCMS80 | DFSCMS80 | Abort Processing (Second LTB) | MSS2 |
| DFSCMS81 | DFSCMS81 | Prior to DDM I/O | DM0I |
| DFSCMS00 | DFSCIO03;06 | Write Setup | DM01 |
| DFSCMS00 | DFSCIO00 | Write Interrupt | DM02 |
| DFSCMS00 | DFSCIO01;03 | Read Setup | DM03 |
| DFSCMS00 | DFSCIO00 | Read Interrupt | DM04 |
| DFSCMS00 | DFSCIO00;03 | Connect/Disconnect I/O Interrupt | DM07 |
| DFSCMEI0 | DFSCMEI0 | Message Control/Error exit processing | CMEI |
| DFSCMEI0 | DFSCMEI0 | Before calling Message Control/Error exit DFSCMUX0 | CMEA |
| DFSCMEI0 | DFSCMEI0 | After calling Message Control/Error exit DFSCMUX0 | CMEB |