Browse Prior Art Database

Telegraph Synchronizer

IP.com Disclosure Number: IPCOM000095087D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 55K

Publishing Venue

IBM

Related People

Heassler, RA: AUTHOR [+4]

Abstract

This apparatus synchronizes a plurality of telegraph signals with a data processing system DPS. A plurality of telegraph lines 10 is scanned by scanner 12 under control of clock 13. This synchronizes the scanning rate of scanner 12 with the recirculation of data in recirculating delay line 14. Each line 10 has associated with it a line control word LCW. Such appears periodically in shift register 16, providing access to the information stored in delay 14. There is one. LCW comprised of nine bits for each line 10. The LCW associated with a telegraph line appears in register 16 at the same time scanner 12 is scanning the associated telegraph line. The LCW's operate common control logic.

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Telegraph Synchronizer

This apparatus synchronizes a plurality of telegraph signals with a data processing system DPS. A plurality of telegraph lines 10 is scanned by scanner 12 under control of clock 13. This synchronizes the scanning rate of scanner 12 with the recirculation of data in recirculating delay line 14. Each line 10 has associated with it a line control word LCW. Such appears periodically in shift register 16, providing access to the information stored in delay 14. There is one. LCW comprised of nine bits for each line 10. The LCW associated with a telegraph line appears in register 16 at the same time scanner 12 is scanning the associated telegraph line. The LCW's operate common control logic. This is comprised of strobe counter incrementer and decoder 18, sync decoder 20 and And and Or logic for performing various control sequences.

The timing drawing shows a start-stop signal as it appears on a line 10. The telegraph signal, waveform a, is ordinarily in mark status, i. e., positive. When a space condition, i. e., negativity, is sensed on a line 10, the scanner 12 output 22 goes negative. This allows an output from an oscillator in clock 13 to increment the strobe counter field 15 by a serial adder in counter 18. The information in delay 14 can recirculate many times before the midpoint of the telegraph signal occurs. To accommodate this, the count is stored in field 15 and is incremented each time there is an oscillator change. In order to sense that the oscillator has changed during the recirculation of delay 14, the status of the oscillator on the previous revolution is stored in the bit position LOSC. Thus, each time delay 14 rotates, the last oscillator condition LOSC is compared with the present oscillator condition.

If there is a change, field 15 is incremented one bit position.

When field 15 reaches a predetermined value, which establishes one half of a bit period, counter 18 emits an output labeled strobe time.

The strobe time occurs at the midpoint of the start signal as shown by the first arrow in waveform b. If a space condition exists at strobe time, i. e., a start bit, the sync 1 and sync 2 control bits are changed to the status 01. This is accomplished by And 26. Such emits a pulse upon the coincidence of an idle status of sync bits 1 and 2, a space on the telegraph line, and an output at strobe time. The output of And 26 sets sync bit 2, waveform g.

Counter 18 is allowed to continue running and incrementing for the duration of the telegraph character. At every strobe time...