Browse Prior Art Database

Tape Reader Control

IP.com Disclosure Number: IPCOM000098174D
Original Publication Date: 1960-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 66K

Publishing Venue

IBM

Related People

Greenhalgh, RC: AUTHOR [+2]

Abstract

Where data are read from a paper tape into storage in a computer it is desirable to check whether the data read are accurately stored in the computer. After reading a character into storage, the computer, through a control unit, instructs the tape unit to reread the character for comparison with the stored character.

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Tape Reader Control

Where data are read from a paper tape into storage in a computer it is desirable to check whether the data read are accurately stored in the computer. After reading a character into storage, the computer, through a control unit, instructs the tape unit to reread the character for comparison with the stored character.

This checking system, shown in the upper drawing, requires a tape reader 10 which stops on the character sprocket bit, brakes under remote electrical control, clutches under remote electrical control, and scans the tape even while braked. The system includes a control unit 11 and a computer 12 which is capable of performing checking functions on input data, calls for input data by Select and Copy signals, controls coincidence of Copy and Select signals and time- sequence relationship of Select signals to command the tape unit to read, reread, halt tape or reread stationary tape.

As an example, the paper tape is photoelectrically read serially by character, parallel by bit. The mark bits of the character currently being read condition lines 13 of gate 20. The sprocket hole currently being read conditions line 14. Control unit 11 is responsive to conditioning of sprocket line 14 by the paper tape unit, and conditioning of select line 15 and copy line 16 by the computer. Properly conditioned, and under its own internal control, the control unit 11 selectively conditions brake line 17 or clutch line 18 to cause or inhibit the operation of the paper tape transport. The control unit also conditions read-in line 19, which conditions gate 20 for data transmittal to the computer via gated data lines 21. The control unit additionally conditions drop copy line 22 and drop select line 23 which makes possible a sequence and time coding of Select and Copy signals to control paper tape transport, reading and rereading.

The procedure is to read and store a character which is adjacent the read station, check the character, and proceed to the succeeding character if the stored character corresponds to the tape character.

The Sprocket signal persists for the duration of the period during which the tape is stopped. The computer, when the need is sensed, prepares for reception of the character by first conditioning select line 15, and, slightly later, conditioning copy line 16. The coincident conditioning of select and copy lines 15 and 16 operates AND circuit 24 in the lower drawing to condition select-copy line 25 which sets clutch brake latch 26 to clutch, thus initiating tape transport. The four input AND circuit 27 operates on coincidence of select, copy, sprocket and stop Latch On signals via lines 15, 16, 14 and 28, respectively. Conditioning of the AND output line 29 fires readin single shot 30, conditioning line 31 to Gate Data via line 19, to Drop Copy via line 22 and to reset stop latch 32 to off.

Readin single shot 30 has a 50 microsecond duration...