IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Interruptions to System/7The program in the 1130 can request an interruption to the System/7 processor module.The interrupt priority level, sublevel, and device address are fixed for the 1130 hostattachment; therefore, no prepare I/O command is required. As directed by a bit in aninitiate read or initiate write IOCC, the request to the System/7 processor is made onpriority level 3 with a sublevel of 0. The interruption request presented to the System/7by the 1130 is handled the same as any other priority interruption request as described inChapter 3 under "Priority Interruptions." When the processor services the request, the1130 host attachment presents a device address of 011100.INSTRUCTIONS AND COMMANDS FOR 1130 SYSTEMStandard 1130 I/O instructions and control commands are used to program the hostattachment from the 1130. An 1130 execute I/O (XIO) instruction is issued to address theappropriate IOCC. The IOCC specifies the operation to be performed and the device towhich the operation is directed. For data transfer operations, the IOCC also specifies theword count or address of the data to be transferred. For a general description of the X10instruction and IOCC's, refer to the manual /BM 1130 Functional Characteristics, OrderNo. GA26-5881.I/O Control Commands (IOCC)An IOCC must start at an even storage address in the 1131 processor and has the followingformat:0 16 21 24 31Word count/address Device 'Fun Modifier0 1 1 0 0 X X X 0 0 0 0IXX XXMilli' t I I I I 1 I I I I I I I I IX X X X 6 1-7 0 XThe IOCC fields are described as follows:Word Count/Address: This field is used to pass the three values required by the 1130 hostattachment in order to perform a data transmission: (1) a transmission word count, (2) aSystem/7 storage address, and (3) an 1130 storage address. The count specifies the numberof data words to be transferred. The addresses establish the beginning of the data tablesbetween which the data transfer is to occur. The count and one of the addresses aretransferred to System/7 storage by two separate control IOCC's. The third value, anaddress, is transferred by the 1130 initiate read or initiate write IOCC.Device: This 5-bit field identifies the I/O device to which the IOCC is directed. In thiscase, a binary 01100 is the code identifying the System/7.Function (Fun): The 3-bit function code determines the specific I/O operation to beperformed.Modifier: This 8-bit field provides additional information, when necessary, for thefunction specified.16-4 GA34-0003