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Magnetic Drum Memory Organization for Implementing Symbolic Addressing

IP.com Disclosure Number: IPCOM000096307D
Original Publication Date: 1963-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 4 page(s) / 69K

Publishing Venue

IBM

Related People

Tasini, BB: AUTHOR

Abstract

The magnetic drum memory organization implements symbolic addressing by establishing information streams on the drum in a spiral manner. The starting point of any variable length information stream is determined within one drum revolution by presentation of a tag to the drum memory

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Magnetic Drum Memory Organization for Implementing Symbolic Addressing

The magnetic drum memory organization implements symbolic addressing by establishing information streams on the drum in a spiral manner. The starting point of any variable length information stream is determined within one drum revolution by presentation of a tag to the drum memory

The organization of the magnetic drum memory (MDM) 10 is shown in A. Only information paths are shown. Control and timing lines are omitted. MDM 10 consists of a number of tracks, each being activated by its own read/write head. The tracks are grouped into information bands 1,... M, each consisting of q tracks, where q is the number of bits comprising a character as specified by the character code. Each information path consists of q physical transmission paths, except the timing, the Where Was I (WWI) and the (AVL) availability channels. A band defines an actual transmission path of information in a parallel by-bit, serial- by-character, transmission mode. It also defines the locus of information storage on the MDM 10 surface.

The information bands share a common set of q read/write amplifiers selected by a band switch incorporated in read/write circuitry and band switch 12. Switch 12 is controlled by M-stage ring 14. Information is channeled to or from a particular band at an appropriate instant Ti. The control signals T1... TM are generated by ring 14. Timing channel 16 furnishes the fundamental clock signal
C. Notation with C denote a particular time period measured from some time origin of the fundamental clock pulse train. The timing channel also supplies a single home pulse C00 which occurs once per revolution of drum 10.

The retrieval aspect of MDM 10 is described first. The tag representing either an operand or the beginning of a stream of information is transmitted from central processing unit (CPU) 18 to retrieval location register (RLR) 20. P denotes the maximum number of characters allowable in a tag. The capacity in binary bits of RLR 20 is pq. Once the binary-bit configuration of the tag is stored in RLR 20, a search for a match between the contents of RLR 20 and its replica in the retrieval location channels (RLC) 22 is initiated. The match is indicated by the MTC signal from the compare circuit 24. RLC 22 is a pq parallel-by-bit transmission path. Assume that the information in RLC 22, for which a match with the contents of RLR 20 is sought, was written in RLC 22 to coincide with CJ in B. Drawing B is a timing chart of information streaming for m=8. The signal MTC from compare circuit 24 starts the ring 14 so that T1 enables band 1 coincidentally with CJ + 1 to transmit one character into CPU 18. As ring 14 advances, the other information bands transmit a character at a time to CPU 18. The ring 14 signals last for a sufficient length of time to allow a character to be read from drum 10. The transmission of information proceeds cyclically with the ring 14 signals. The...