| Field | Subfield | Description |
|---|---|---|
| 00 | Interface Type 0 = MLI interface 1 = IPI Interface 2-F = Reserved |
|
| 01 | IOP Variant Extension (Presently zero) | |
| 02-03 | IOP Variant. Setup by software, used unmodified by the IOS | |
| 02 | 3 = Inhibit Data Transfer to memory 2 = Backwards Read 1 = ASCII Translation 0 = Real Time |
|
| 03 | 3 = Reserved 2 = Reserved 1 = Bypass I/O complete Queue (Software polls IOP R/D for completion) 0 = Conditional Cancel Flag |
|
| 04-13 | Buffer Begin Address. Absolute Value Used and modified by IOS Content not guaranteed at I/O complete. May be Set by CIO |
|
| 14-23 | Buffer Size Number of digits to transfer by IOS Initial Value Only. |
|
| 24-27 | IOP Accumulated R/D. Compatibility Notes A.64 | |
| 28-31 | Remaining Data Length & R/D Field Offset. Offset relative to current IOCB begin address. |
|
| 32-33 | Reserved | |
| 34-39 | Buffer MAST Number Memory Area nailed by CIO Not used by IOS. Used by IOC to unnail Memory Area |
|
| 40-43 | Special R/D Used by software only Valid only if Bypass I/O complete queue bit set in IOP Variant Value “8000” = I/O completed. Value “0000” = I/O not completed. |
|
| 44-45 | Unit Number Compatibility Notes A.64 | |
| 46-49 | Channel Number Where the DLP command is sent Set by Software See Compatibility Notes A.24 |
|
| 50-NN | DLP Command or I/O Op Code MLI: NN=69 IPI: To Be Specified Built by software Set unmodified by IOS to DLP except for Unconditional Cancel |
|
| MM-PP | Remaining Data Length and Result Descriptors MLI: MM=70, PP=107 IPI: To be specified Used and modified by IOS Content guaranteed at I/O complete |
| Field | Subfield | Description |
|---|---|---|
| 50-69 | DLP Command - MLI Interface | |
| 50 | DLP Op Code C = Unconditional Cancel 8 = Read 4 = Write 2 = Test 1 = Echo |
|
| 51-53 | DLP Variants | |
| 54-61 | Peripheral Device Information Formerly known as the C-Address |
|
| 62-69 | Peripheral Device Information Extension Number of bytes (Buffer Size divided by two) in binary to be transfered to the device |
| Field | Subfield | Description |
|---|---|---|
| 70-107 | Remaining Data Length and Result Descriptors - MLI Interface Only current I/O operation relevent field updated by hardware |
|
| 70-79 | Remaining Data Length Number of digits not transferred Used and updated by IOS Content guaranteed at I/O Complete May be set by CIO |
|
| 80-83 | IOP R/D Compatibility Notes A.64 | |
| 84-91 | DTM R/D Compatibility Notes A.64 | |
| 92-107 | DLP R/D |
The remainder of the IOCB is reserved for software use.