Browse Prior Art Database

Cross Channel Switch

IP.com Disclosure Number: IPCOM000096279D
Original Publication Date: 1963-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Brady, RL: AUTHOR

Abstract

To permit two separate and independent systems A and B to share the use of a single device, such as a random access disk file, tie-breaking circuitry and interlocks are provided to prevent simultaneous selection of the device by more than one system. Each system is provided with a select request line and a select reset line. The select request line indicates the corresponding system desires use of the file. The select request line A is supplied as one input to set gate 11. This provides an output to system A select latch 12. Latch 12 has on and off output lines. The off output line connects as one input to the corresponding set gate 13 for system B. System B has a similar select latch 14 whose off output line connects as one input to the system A gate 11.

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Cross Channel Switch

To permit two separate and independent systems A and B to share the use of a single device, such as a random access disk file, tie-breaking circuitry and interlocks are provided to prevent simultaneous selection of the device by more than one system. Each system is provided with a select request line and a select reset line. The select request line indicates the corresponding system desires use of the file. The select request line A is supplied as one input to set gate 11. This provides an output to system A select latch 12. Latch 12 has on and off output lines. The off output line connects as one input to the corresponding set gate 13 for system B. System B has a similar select latch 14 whose off output line connects as one input to the system A gate 11. The third input to gate 11 is supplied from a Try A line representing one output from oscillator 16. This generates alternate Try A and Try B pulses. These are spaced in time from each other by intervals approximately equal to the pulse duration, as shown.

Assuming system A requests use of the file, request line A is energized to supply an input to gate 11. If latch 14 for system B is off, gate 11 opens at the next Try A pulse in the output from oscillator 16. This turns latch 12 on to supply an output to And 21 in the system A select output. And 21 thus ands through request A line to the file. The output from latch 12 is also supplied as an input to And 22 in the system B output line. With the file selected for system A, the data transfer between system A and the file then proceeds.

If system B requests use of the file while system A is selected, latc...