GB1260888A - Improvements in or relating to memory store arrangements - Google Patents

Abstract

1,260,888. Programmed position control. SIEMENS A. G. July 2, 1969 [July 3, 1968], No. 33429/69. Heading G3N. A memory storage arrangement, having one or more plate-like storage layers each carrying a plurality of tracks, includes a mounting, carrying read and write heads, which is positioned by a linear hydraulic motor. As shown, read-in and write-out heads 12, mounted on a common slide 14 are positioned with respect to a stack of memory storage plates 10 by a piston 28 in a cylinder 26. The position of the piston 28 is controlled by parallel-connected variable flow valves 22, 24. The position of the slide 14 is determined by an indicator 70 comprising linear inductance 72, arranged along a fixed guide for the slide, supplied from an A. C. source 74 and a coupled winding 76 on the slide. The voltage induced in the winding 76 has a frequency corresponding to that of the source 74 and an amplitude which varies in a sinusoidal manner with change in the relative position of the windings. The induced voltage is fed through an amplifier 78 to a phase-sensitive rectifier 80, producing a sinusoidal output and to a threshold detector 82 producing a pulse output each time the output voltage of the amplifier passes through zero. Each pulse is representative of the crossing of a storage track. Programme information from a data-processing installation, (not shown), is set into a control unit 90 and the required change in track position is fed, as a binary number, to a track difference register 50 the contents of which is fed to a decoder 52 together with an indication of sign R, V, denoting return or feed respectively. The output from the decoder 52 is fed via lines R or V, through a digital-analogue converter 54 to an amplifier 56 controlling a valve 22 and through a switch 58 to an amplifier 60 controlling a valve 24. In a coarse positioning mode a first controller system employing the pulse output of the indicator 70, counts down the contents of register 50 whereby the output of the digital-to-analogue converter 56, falls in a step-wise manner and the positioning rate decreases as the flow-rate through valve 22 drops to zero. When the contents of the register reaches zero the switch 58 is operated and a second controller system, employing the sinusoidal output of indicator 70, is brought into operation and the valve 24 controlled in a continuously variable analogue manner by the differential amplifier 60 to position the heads 12 at the programmed track. During the step-wise control of valve 22 the valve 24 remain fully open.