GB1432227A - Information-processing systems - Google Patents

Abstract

1432227 Digital data processing COMPAGNIE HONEYWELL BULL 11 April 1973 [18 April 1972] 17516/73 Heading G4A Each of a plurality of control units, one of which 2a is shown in Fig. 1 control communication between a central unit 1 and an associated group of peripheral units. The central unit 1 comprises a main store 11 and read only store 12, with a section 122 assigned to calculation tables and a section 121 assigned to micro programmes, linked to a processor 13. The control unit comprises a read only store 21, register section 22 and switching section 23. Memory 21 is addressed from a register (S, Fig. 2, not shown) and read out to further registers (N, F) one of which is selected to read an address and micro-function in accordance with the state of a bi-stable (bs), read out occurring at a clock pulse (XTLEV) and addressing at a clock pulse (XTAD). The bi-stable is controlled by two signals (VAR, VAR) to select the next micro function in accordance with the current value of the signals and the output of a comparator (CL, Fig. 4, not shown) which compares data in a plurality of registers or fixed data with data in a selected register (L, Fig. 7, not shown). To communicate between the central unit 1 and a peripheral disc storage unit the central unit transmits five control words. A service signal (DIR, Fig. 3, not shown) is received by the central unit when selection of the control unit is assumed to have been made which causes a control word fed to a register (U) to be decoded by a decoder (DD) to derive a signal (sel 1 ...) to select one of the peripheral units and a signal (sp) to set a bi stable (bm, Fig. 2, not shown) to derive a start signal for a micro programme held in the memory 21. A micro-function is consequently generated which sets bi-stable (bk, Fig. 4, not shown) to deliver a signal to the central unit. The central unit responds with a control word which is fed to a register (P, Fig. 7, not shown), bi-stable (bk, Fig. 4, not shown) being simultaneously reset. The next microfunction (TPL) results in the contents of the register (P) being transferred to the register (L), the bi-stable (bk) being again set to transmit a signal to the central unit for admission of the next control word. Successive control words are entered into registers (A, B, C) and represent the numbers of the sector, head and track to be selected and indicate that a positioning function is needed. The last address processed is held in a register associated with the peripheral unit, positioning being effected by comparison between the old and new addresses. The last control word specifies a read/write operation, data being received from the disc serially. A test operation of the control unit may be effected by transferring from the central unit the appropriate five control words.