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Handling Bulk Data From the Minnow Disk

IP.com Disclosure Number: IPCOM000075501D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Beard, JN: AUTHOR [+5]

Abstract

Dedicated disk memories are in use as entry vehicles for loading programs into machines, which utilize microprogramming control in a Read/ Write memory. This loading is usually accomplished by the use of a programmed sequence of commands. These commands are not a reentrant type of program such as might reside in core storage, but rather a sequential type of program where each command is only executed once per pass. The commands are recorded on the disk itself and executed sequentially as the disk rotates. The data to be entered in Read/Write memory follows each command on the disk, and since each command in the sequence is more or less independent of the other commands, a unique command is required for each segment of data to be transferred.

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Handling Bulk Data From the Minnow Disk

Dedicated disk memories are in use as entry vehicles for loading programs into machines, which utilize microprogramming control in a Read/ Write memory. This loading is usually accomplished by the use of a programmed sequence of commands. These commands are not a reentrant type of program such as might reside in core storage, but rather a sequential type of program where each command is only executed once per pass. The commands are recorded on the disk itself and executed sequentially as the disk rotates. The data to be entered in Read/Write memory follows each command on the disk, and since each command in the sequence is more or less independent of the other commands, a unique command is required for each segment of data to be transferred. The amount of data contained in each segment is governed by the feasible size of the data register used to buffer this data as it comes from the disk.

Consider a hypothetical machine with a feasible data register of four bytes to buffer data and a one-byte command register. In order to transfer four bytes of data, a byte of command is necessary. Since the file is a sequential device, this means that one out of every five bytes on the disk or 20% of the disk space is not available for storing the memory data, since it is needed for the commands. If a smaller data register is necessary, more space is lost on the disk. A reduction in the loss of space could be obtained with a larger data register; but on many smaller machines, this approach is not a feasible solution. In both cases, considerable file space is lost due to the command bytes. This situation is intolerable, since it increases the number of different "disks" needed to contain software for a given machine configuration.

More usable data on the physical disk is obtained through the use of the present arrangement, in which a "bootstrap" routine is placed in memory and takes the place of the major part of the sequential programming on the disk. A significant feature of this approach is a hardware bit which controls the file sequence of operation, but is controlled by the "bootstrap" routine in memory and the use of a special command called "Bulk Move." These features alleviate the need for the multiplicity of command bytes from the disk, thus gaining more space for the loadable data.

The "Bulk Move" command, when decoded, presents a consta...