Apparatus for interconnecting a control unit having a parallel bus with a channel having a serial link

Claim 2

In an I/O subsystem of a data processing system having a serial control unit operable according to serial frames on a serial link, a parallel control unit operable according to the protocol of a parallel bus, a channel (15) operable in a serial mode with the serial channel and operable to form Command frames and Data frames defining operations on the parallel bus in the execution of a channel program having one or more CCW's, a set of CCW's for one data transfer command being designated a CCW record, an extender unit (22) comprising means for connecting the extender unit to operate with a parallel control unit on a bus according to the parallel bus protocol, means for connecting the extender unit to send frames (52) to the channel and to receive frames (28) from the channel on a serial link, means for recognizing in a frame for a data transfer a flag defining the end of a CCW (CDAEND) and a flag defining the end of a CCW record (END) and means responsive to said flags for performing operations associated with the end of a CCW and the end of a CCW record.

Claim 3

The extender unit (22) of claim 1 wherein the said extender unit includes means responsive to a frame from the channel containing a flag defining the end of a CCW (CDAEND) for returning a corresponding flag (CDAEND) to the channel when the data transfer for the frame has been completed and means responsive to a frame from the channel containing a flag defining the end of a CCW record (END) for returning a corresponding flag (END) to the channel when the data transfer for the frame has been completed.

Claim 4

The extender unit of claim 2 wherein one operation of the said extender unit (28) associated with the end of a CCW record is command chaining for executing a following CCW record.

Claim 5

In a data processing system having a. an I/O device (17), b. a parallel bus (24), c. a control unit (19) connected between the bus and the device and having means for operating on the bus according to a protocol for data transfers and for handling status from the device, d. and a channel (15) connectable to the control unit in part by a serial link (20, 18) and having means for sending and receiving serial frames on the link and having means for executing channel programs, including means for testing device status, an extender unit (22) comprising e. means for performing data transfers and other operations on the parallel bus including receiving device status from the control unit, f. means for sending (52) and receiving (28) serial frames on the link to the channel including 1. an inbound frame containing device status, 2. an outbound frame containing a command to be executed with the control unit, 3. and an outbound frame for a data transfer including a flag defining the end of a CCW record and a flag defining that another operation it to follow, subject to a test of device status by the channel, g. means responsive to the completion of a data transfer to be followed by another operation to 1. send a status frame to the channel, 2. begin the next operation, 3. cancel the operation if a frame is received from the channel canceling the operation, 4. or continuing the operation if a frame is received from the channel continuing the operation.

Claim 6

In a data processing system having a. an I/O device (17), b. a parallel bus (24), c. a control unit (19) connected between the bus and the device and having means for operating on the bus according to a protocol for data transfers and for handling status from the device, d. and a channel (15) connectable to the control unit in part by a serial link (20, 18) and having means for sending and receiving serial frames on the link and having means for executing channel programs, including means for testing device status, an extender unit (22) comprising e. means for performing data transfers and other operations on the parallel bus including receiving device status from the control unit, f. means for sending (52) and receiving (28) serial frames on the link to the channel including 1. an inbound frame containing device status, 2. an outbound frame containing a command to be executed with the control unit, 3. and an outbound frame for a data transfer including a flag defining the end of a CCW record and a flag defining that another operation it to follow, subject to a test of device status by the channel, g. means responsive to the completion of a data transfer to be followed by another operation to 1. send a status frame to the channel, 2. begin the next operation, 3. cancel the operation if a frame is received from the channel canceling the operation, 4. or continuing the operation if a frame is received from the channel continuing the operation.

Claim 7

In a data processing system having A. a parallel bus (24), B. an I/O device (17) having a gap between records during which command chaining reselection can be performed, C. a parallel bus, D. a control unit (19) connected between the bus (24) and the device (17) and having means for operating on the bus according to a protocol for a. data transfers, b. initial selection of a device, c. handling status from the device, d. and command chaining reselection of the device when one record of a channel program is followed by another record, the control unit having the requirement when command chaining takes place during a record gap to receive the next command within a predetermined interval, and on a write operation, to receive the first byte within a predetermined interval after receiving the command, E. and a serial channel (18, 20) having a serial link, an extender unit (22) comprising F. means for sending and receiving serial frames on the link to the channel, including 1. means (28) for receiving a Data type frame to execute a read or write operation with the control unit 2. means for decoding in a data type frame a flag defining the end of a CCW record that is to be followed by another CCW record so that command chaining reselection is required, subject to a conventional check of device status and other conditions to be made by the channel, 3. means (42) for communicating with the control unit on the parallel bus according to the bus protocol, 4. means operable when command chaining is in effect for checking device status to determine whether the control unit has reported certain conditions a. an error requiring intervention by the channel b. the condition that the device status will be reported later 5. means operable when command chaining is in effect to send the status byte to the channel with a bit set to signify that the extender unit is executing automatic command chaining reselection, 6. means for beginning command chaining according to the parallel bus protocol without regard to the operation in the channel to check status and other conditions, whereby the timing requirements of the device are more readily met.

Claim 8

In a data processing system having A. a parallel bus (24), B. an I/O device (17) having a gap between records during which command chaining reselection can be performed, C. a parallel bus, D. a control unit (19) connected between the bus (24) and the device (17) and having means for operating on the bus according to a protocol for a. data transfers, b. initial selection of a device, c. handling status from the device, d. and command chaining reselection of the device when one record of a channel program is followed by another record, the control unit having the requirement when command chaining takes place during a record gap to receive the next command within a predetermined interval, and on a write operation, to receive the first byte within a predetermined interval after receiving the command, E. and a serial channel (18, 20) having a serial link, an extender unit (22) comprising F. means for sending and receiving serial frames on the link to the channel, including 1. means (28) for receiving a Data type frame to execute a read or write operation with the control unit 2. means for decoding in a data type frame a flag defining the end of a CCW record that is to be followed by another CCW record so that command chaining reselection is required, subject to a conventional check of device status and other conditions to be made by the channel, 3. means (42) for communicating with the control unit on the parallel bus according to the bus protocol, 4. means operable when command chaining is in effect for checking device status to determine whether the control unit has reported certain conditions a. an error requiring intervention by the channel b. the condition that the device status will be reported later 5. means operable when command chaining is in effect to send the status byte to the channel with a bit set to signify that the extender unit is executing automatic command chaining reselection, 6. means for beginning command chaining according to the parallel bus protocol without regard to the operation in the channel to check status and other conditions, whereby the timing requirements of the device are more readily met.

Claim 9

A Data processing system including a plurality of I/O devices (17) and control units (19), the control units (19) having means for sending a status byte at the end of one operation before disconnecting and beginning a subsequent operation, and a control unit having a characteristic delay between the operation of reading a last byte of one operation and transmitting the corresponding status byte, a main memory (13), and a channel (15) for data transfers between the devices and main memory, including a serial link (18, 20) for communicating with device control units, and means for forming serial frames on the serial link, a buffer for holding bytes from the channel (15) for transmission to the main memory, means for handling incoming frames on the link including means for detecting an idle character, means for detecting a frame having a flag signifying a data character requiring microcode handling and a data frame not having such a flag, and means for storing the data frames and for invoking the microcode on receipt of frames having the flag set, a data stager (16) including a buffer for transferring bytes from the channel (15) to main memory (13), and an extender unit (22) operable with a control unit (19) including means (52) for sending frames to the channel (15) on a read operation whenever one or more bytes are available from the control unit (19), the frame forming rate of the extender unit (22) being related to the data rate of various devices such that a frame from the extender unit has a smaller number of bytes for faster devices and a larger number of bytes for slower devices, wherein the improvement comprises a counter in the channel, means for resetting the counter when a frame is detected having said larger number of data bytes, means for advancing the counter on the occurrence of an idle character, whereby the count signifies a delay between frames of a faster device, means responsive to a predetermined count in the counter to transfer any remaining bytes in the channel buffer or in the data stager buffer to main memory, whereby data is stored in main memory before the device status is received and an operation in the device requiring an action by the extender unit within a limited time is not delayed.

Claim 10

A Data processing system including a plurality of I/O devices (17) and control units (19), the control units (19) having means for sending a status byte at the end of one operation before disconnecting and beginning a subsequent operation, and a control unit having a characteristic delay between the operation of reading a last byte of one operation and transmitting the corresponding status byte, a main memory (13), and a channel (15) for data transfers between the devices and main memory, including a serial link (18, 20) for communicating with device control units, and means for forming serial frames on the serial link, a buffer for holding bytes from the channel (15) for transmission to the main memory, means for handling incoming frames on the link including means for detecting an idle character, means for detecting a frame having a flag signifying a data character requiring microcode handling and a data frame not having such a flag, and means for storing the data frames and for invoking the microcode on receipt of frames having the flag set, a data stager (16) including a buffer for transferring bytes from the channel (15) to main memory (13), and an extender unit (22) operable with a control unit (19) including means (52) for sending frames to the channel (15) on a read operation whenever one or more bytes are available from the control unit (19), the frame forming rate of the extender unit (22) being related to the data rate of various devices such that a frame from the extender unit has a smaller number of bytes for faster devices and a larger number of bytes for slower devices, wherein the improvement comprises a counter in the channel, means for resetting the counter when a frame is detected having said larger number of data bytes, means for advancing the counter on the occurrence of an idle character, whereby the count signifies a delay between frames of a faster device, means responsive to a predetermined count in the counter to transfer any remaining bytes in the channel buffer or in the data stager buffer to main memory, whereby data is stored in main memory before the device status is received and an operation in the device requiring an action by the extender unit within a limited time is not delayed.