公开(公告)号：DE1524771A1

公开(公告)日：1970-12-10

申请号：DE1524771

申请日：1967-01-16

Applicant: IBM

Inventor： FRANCIS BEAUSOLEIL WILLIAM ,  STANLEY ROHDE RICHARD ,  MORTON SMITH RONALD ,  ZEIGER HENRY

IPC: G06F11/07 ,  G06F11/16 ,  G11C29/00

公开(公告)号：DE1499687A1

公开(公告)日：1970-04-30

申请号：DEJ0030752

申请日：1966-05-05

Applicant: IBM

Inventor： FRANCES BEAUSOLEIL WILLIAM ,  ALBERT CLARKE WILLIAM ,  MORTON SMITH RONALD ,  ROHRBACH HILL PETER

IPC: G06F7/50 ,  G06F12/14 ,  G06F13/12 ,  G06F13/00

Abstract: 1,142,465. Data processors. INTERNATIONAL BUSINESS MACHINES CORP. 2 May, 1966 [12 May, 1965], No. 19173/66. Heading G4A. In a data processing system, access to an address in peripheral storage is permitted or prevented in accordance with the result of a comparison of the address with information developed from a stored catalogue of addresses available to the current programme. A CPU (central processing unit) with associated main core storage can communicate via channels with external devices viz. input/output units and storage units (e.g. disc units). A stored catalogue, in the main storage or an external storage unit, specifies for each data file in an external storage unit, the boundaries of the file (high and low, cylinder and head numbers in the case of a disc unit) and the types of writing and reading access permitted to the associated problem programme. Other problem programmes are denied all access. The control unit of an external storage unit, on being selected for storage access, receives the relevant information from the catalogue byte by byte, the bytes being passed on respective odd counts of a counter in the control unit, from an in - put/output register which initially receives them, to respective further registers in the control unit. The access attempt is terminated and the CPU interrupted and informed of the reason, if the input/output register does not hold zero on any even count, during this. In the absence of this error indication, the cylinder and head numbers of the desired address are received into the input/output register in turn and compared with the boundary bytes in turn, under control of the counter, in the following order (disc unit): cylinder high, cylinder low, head high, head low. The required cylinder and head are selected as soon as their respective comparisons say yes, but if any comparison says no, the access attempt is terminated without further comparisons and the CPU interrupted as before. Termination &c. will also occur if the access is of a non-permitted type, as determined in the control unit, or if the input/output register does not hold zero at certain times before and after the comparisons. Cylinder selection involves finding the difference between the present and desired cylinder numbers, in an adder. A circuit is provided to detect any attempt to set said further registers with more than one set of information from the catalogue. In a modification mentioned, the catalogue supplies two bits specifically allowing or forbidding movement from the current head and cylinder respectively, instead of the boundary data. Conventional arrangements for selection of an external device, including transmission of status back, are described.