GB1210337A - Improvements to systems for data transfer between direct access memory and magnetic drum or similar storage memory - Google Patents

Abstract

1,210,337. Drum/core transfer system. INTERNATIONAL STANDARD ELECTRIC CORP. 12 Feb., 1969 [16 Feb., 1968], No. 7654/69. Heading G4C. A system for transferring data between a drum store and a core store is characterized in that (a) To each sector of a track on the drum is uniquely associated a one-word store within the core store-these one-word stores being collectively referred to as a " sector table "; (b) In each one-word store of the sector table an address is stored of the position within the core store that a transfer instruction relating to the drum sector corresponding to the oneword store will be found; and (c) As each sector of the drum becomes accessible, the corresponding one-word store in the sector table is read-out to cause the transfer instruction relating to that sector to be read out and implimented. As described, whenever a transfer instruction occurs during the performance of a programme, it is read into a particular segment in the core store, each segment being large enough to hold several transfer instructions and corresponding to the sector of the drum that is involved in the transfer. Thus, each of these segments holds a queue of transfer instruction relating to the associated sector on the drum. The address of the first instruction in the queue is stored in the associated one-word store of the sector table. As the drum rotates a sector counter and a word counter indicate the sector and word currently accessible. Each time the sector counter changes, the sector table is consulted to find the address of the first transfer instruction in the core store that is awaiting implimentation. This instruction is read out and immediately obeyed-this being possible because the drum is necessarily appropriately positioned. At the end of the transfer, the sector table is up dated so that it holds the address of the next transfer instruction.