Data processing system with a plurality of peripheral devices

Claim 2

1 A data processing system including a host processor (12), a control unit (11) and a plurality of peripheral devices (13), characterised by first connection means (30) for coupling the control unit to the peripheral devices for the transmission of data signals and timing signals, second connection means (31) for coupling the control unit to the peripheral devices for the transmission of device selection signals, and third connection means (32) for coupling the control unit to the peripheral devices for transmission of preparation signals to enable a peripheral device, other than that selected by the second connection means signals, to prepare for later receipt of data signals on the first connection means.

Claim 3

2 A system according to claim 1, in which the first connection means includes a data path means for transferring data signals and timing path means for timing transmission of data signals transmitted over the data path means, the second connection means includes separate circuit means in each peripheral device and the control unit for bidirectionally transferring multiple tag signals between the control unit and said devices for selecting a device to transfer data signals over the data path means, tag signals signifying status, first connection command signals and data signals being transferred over the data path means, the third connection means being independent of the first and second connection means and including command conducting means for carrying command signals having address signals from the control unit for another device indicated by address signals, and third connection circuit means in each peripheral device connected to the command conducting means and being responsive to an appropriate address signal to decode command signals, and further means in each device responsive to decoded commands to actuate the device to prepare for receipt of predetermined first connection command signals, or to deactivate the device, whereby signal transfers over the first and second connection means are inhibited or released for signal transfers in accordance with respective ones of said third connection means commands.

Claim 4

3 A system according to claim 2, in which the control unit includes a memory means for storing an indication that an attempt was made to send a third connection command signal to a given device via the command conducting means, and selection means in the control unit responsive to the memory means to activate the given device via the second connection means for transferring data signals over the first connection means via the data path means such that the selection means responds to the memory means even if the given device is not in fact prepared for transferring data signals.

Claim 5

4 A system according to claim 3, in which the third connection means includes means for sending a single binary signal from any one of the devices to the control unit, the third connection circuit means in each device includes means indicating a device preparatory action for a later data-processing function occurring in the device, and means in each third connection circuit means is responsive to a respective one of the device preparatory actions and to one of the third connection command signals to supply the single binary signal.

Claim 6

5 A system according to any preceding claim, in which the third connection means includes a single electrical conductor extending from the control unit to the controlled devices for carrying the command signal and a second single electrical conductor extending from all devices to the control unit for carrying signals from the devices to the control unit.

Claim 7

6 A system according to claim 1, in which each device includes data signal circuit means adapted to be connected to the control unit for enabling selection of the device by the control unit for transferring data and device command signals and including tag control signal circuit means, preparatory circuit means adapted to be connected to the control unit for receiving a subset of the device command signals and control command signals and in response to a subset of device command signals to activate the device to perform preparatory actions for a later transfer of data signals via the data signal circuit means and being connected to the data signal circuit means for inhibiting or enabling operation thereof in response to respective ones of the control command signals, whereby data processing operations are performed via the data signal circuit means, the preparatory circuit means including device address decoding means, command receipt means responsive to the device address decoding means to receive a single control command signal for each decoded device address, whereby the control command signals are received independent of device selection via the preparatory circuit means, and device command means for receiving a plurality of device command signals during a single device selection via the data signal circuit means and connected to the device such that the device responds to commands from either of the circuit means.

Claim 8

7 A system according to claim 6, in which the device includes relatively movable mechanical portions, one of which is capable of carrying information-bearing indicia and another one of which includes indicia-operating means .for performing functions with respect to the one mechanical portion relating to the information-bearing indicia when the mechanical protions have reached a predetermined relative postion, the device being responsive to commands received by either the data signal circuit means or the preparatory circuit means to initiate relative motion of the relatively movable mechanical portions toward the predetermined relative position and being responsive to commands received by the data signal circuit means but not by the preparatory circuit means to initiate a data processing function in the device when the relatively movable mechanical portions reach the predetermined relative position.

Claim 9

8 A system according to claim 1, in which the control unit includes a data signal buffer for temporarily storing data signals being transferred between host processor and devices, decoding means for decoding peripheral commands received from the host processor, and device manager means responsive to decoded peripheral commands to establish a plurality of queues of orders for the devices corresponding to the decoded peripheral commands, a first of the order queues queueing orders for the peripheral devices relating to internal device operations ancillary to data signal transfers between the control unit and the devices; a second of the order queues being for orders to transfer control data signals between the peripheral devices and the control unit and a third of the order queues being for orders to transfer data processing signals between the control unit and the peripheral devices.

Claim 10

9 A system according to claim 8, in which the first connection means is for bidirectionally transferring data-processing signals and data-processing device orders between the control unit and the connected peripheral devices, the second connection means is for bidirectionally transferring tag control signals between the control unit and the connected peripheral devices for selecting, deselecting and controlling one of the peripheral devices indicated by data signals transferred over the first connection means in time coincidence with an ADDRO one of the tag control signals, the third connection means is for transferring control orders having device address signals from the control unit to one of the connected devices indicated by the device address signals; and in which the control unit includes order transfer means for scanning the order queues in sequence from first to third for transferring queued orders to the third connection means for actuating the peripheral devices to perform functions in accordance with the transferred orders including functions preparatory to an expected data signal transfer over the first connection means; prepared device indicating means responsive to the transfer means to indicate that an order was transferred over the third connection means to an indicated prepared device means that relates to the expected data signal transfer; and selected device indicating means responsive to the second connection means to indicate a device that was selected for data transfer via the second connection means, the second connection means including first control means reponsive to the selected device indicating means to inhibit selection of a device, second control means responsive to the prepared device indicating means to activate the second connection means to deselect a selected device at an end of a given data signal transfer to allow selection of the indicated prepared device.

Claim 11

10 A system according to claim 9, including operations priority means for starting operations in the control unit iri accordance with the operation to be performed, the priority means including device operation starting means, including the order transfer means, for starting device related operations including signal transfers as first priority operations, channel transfer starting means for starting host related signal transfers as second priority operations, command execution starting means responsive to the decoding means for starting operations related to execution of received peripheral commands including means for activating the device manager means to schedule device operations to be started by the device operation starting means, means indicating other work to be done, and scan means for scanning the other work indicating means for starting control unit operations relating to the other work as a lowest- ordered priority operation.