Interface system for coupling an indeterminate number of peripheral devices to a central processing unit
First Claim
1. A data processing system comprising a central processing unit having a receptacle through which an interface unit of a peripheral device is connected by an associated cable, said interface unit having a receptacle to which another interface unit may be connected by its own associated cable such that separate cables associated with separate interface units are connected in series, and the interface units are connected in parallel to the central processing unit through the series connected cables, each interface unit being connected to a particular device having its own function of inputting and outputting data words to and from said central processing unit, each interface unit being assigned a unique address code, particular mode-control codes and particular function control codes, and each interface unit having a single input register to receive output words from said central processing unit through said series connected cables, each of said output words being comprised of a predetermined number of binary digits representing either an address code and a mode-control code combined, a function control code or data, means connected to said input register for decoding an address code and a mode control code to select a particular device for a particular mode of operation, means connected to said input register for decoding a function code for controlling a particular function of said particular device within said particular mode, and means responsive to mode control signals transmitted by said central processing unit over said series-connected cables for controlling the utilization of output words stored in said input register as an address code and mode-control code combined, a function control code or data, each interface unit further having gating means for transmission of input data words to said central processing unit through said series-connected cables, each of said input data words being comprised of a predetermined number of binary digits, said gating means being connected to be responsive to said mode-control decoding means.
1 Assignment
0 Petitions
Accused Products
Abstract
A system is provided for coupling an indeterminate number of peripheral devices to a central processing unit (CPU) through a single receptacle. A cable connected to an interface unit (IU) of a first device plugs into the CPU receptacle. Cables of subsequent IUs are plugged into receptacles connected to earlier plugged IUs, thus connecting the cables of all devices in series and the device IU'"'"'s themselves in parallel. One type of IU is for a magnetic tape cassette and includes a timeout circuit to determine when certain types of programming errors have occurred. A binary digit is set in a status register for that and other types of errors. The status register is read under program control of the CPU, thus providing for the flexibility of haulting operation or bypassing the program section having an error for unattended operation of the CPU.
-
Citations
22 Claims
- 1. A data processing system comprising a central processing unit having a receptacle through which an interface unit of a peripheral device is connected by an associated cable, said interface unit having a receptacle to which another interface unit may be connected by its own associated cable such that separate cables associated with separate interface units are connected in series, and the interface units are connected in parallel to the central processing unit through the series connected cables, each interface unit being connected to a particular device having its own function of inputting and outputting data words to and from said central processing unit, each interface unit being assigned a unique address code, particular mode-control codes and particular function control codes, and each interface unit having a single input register to receive output words from said central processing unit through said series connected cables, each of said output words being comprised of a predetermined number of binary digits representing either an address code and a mode-control code combined, a function control code or data, means connected to said input register for decoding an address code and a mode control code to select a particular device for a particular mode of operation, means connected to said input register for decoding a function code for controlling a particular function of said particular device within said particular mode, and means responsive to mode control signals transmitted by said central processing unit over said series-connected cables for controlling the utilization of output words stored in said input register as an address code and mode-control code combined, a function control code or data, each interface unit further having gating means for transmission of input data words to said central processing unit through said series-connected cables, each of said input data words being comprised of a predetermined number of binary digits, said gating means being connected to be responsive to said mode-control decoding means.
- 9. A system for coupling an indeterminate number of peripheral devices to a central processing unit through a single receptacle for direct synchronous communications between said unit and any selected one of said devices in response to programmed instructions, said system comprising an interface unit for each device, each device interface unit having a cable adapted to be plugged into a receptacle through which signals are transmitted to and from said central processing unit, and having a receptacle into which a cable of another device interface unit may be plugged in, thus connecting cables of all device interface units in series and the device interface units in parallel, each interface unit being organized in the same way for two-way communication over separate series-connected lines in said series-connected cables for communication in each direction, and having a single control register connected to said cable to receive both data and control code groups of binary digits under control of mode control signals from said central processing unit transmitted through separate lines over said cable means for decoding an address code in a received control code group of binary digits by comparison with a fixed code assigned to the interface unit and its connected peripheral device, means responsive to both said address decoding means and said mode control signals for controlling the utilization of groups of binary digits as data and control codes, and for storing and decoding a control code group of binary digits subsequent to a control code group having said address code when said mode control signals are in a control transfer mode, but only by the addressed interface, said storing and decoding means providing static decoded control signals until said mode control signals are again in the control transfer mode to address an interface unit, and means for transmitting synchronizing clock pulses to all interface units in parallel by said central processing unit through said series-connected cables.
- 20. A data processing system in which a central processing unit transfers blocks of data to a magnetic tape and recieves blocks of data from said magnetic tape through an interface unit under programmed instruction control of said central processing unit, said blocks of data stored on said magnetic tape being separated by blank inter-record gaps, said interface unit including a status register and, means for detecting inter-record gaps, time-out means for timing out a predetermined period greater than a maximum time required to drive said magnetic tape past a read station from one interrecord gap to another, means for resetting said timeout means in response to each interrecord gap detected, and means for entering an error indicating binary digit in said status register, whereby a program in said central processing unit may test for an error in the immediately preceding input-output operation by transferring the contents of said status register to said central processing unit for inspection of said error indicating binary digit.
-
22. A data processing system in which a central processing unit transfers blocks of data to and receives blocks of data from magnetic tape through an interface unit under control of a programmed instruction in said central processing unit, said blocks of data being stored on said magnetic tape in succession, each with a header including an identification number used by said central processing unit for verification of data being addressed by said programmed instruction, each block of data being numbered in sequence from one end of said tape to the other in order for said central processing unit to keep track of magnetic tape position by counting up and down data blocks as tape is driven forward and backward in order to provide a tape position number for comparison with a block position number written as part of said identification number for verification when the block of data which follows on said magnetic tape is again accessed by said central processing unit, said header including a preamble of a predetermined binary code and said interface unit including means for detecting the first ones in sequence of less than the total number of binary digits in said code before commencing to record in response to an instruction from said central processing unit to rewrite a block of data over a recorded block, and means for automatically recording the balance of said preamble in synchronism, followed by said identification number and block of data whereby rewriting a block of data is synchronized by resynchronizing said preamble without requiring separate timing.
Specification