Browse Prior Art Database

Single Track Seek Overlap

IP.com Disclosure Number: IPCOM000082528D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 4 page(s) / 108K

Publishing Venue

IBM

Related People

King, RW: AUTHOR [+2]

Abstract

In a computer system where microcode is used to control the input/output devices, the system time required to transfer data (load) from a (low performance) disk storage drive having a removable disk to a (high performance) disk storage drive having a fixed disk and to transfer data (dump) from the high performance to the low-performance disk storage drive, is significantly reduced with minimal additional apparatus.

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Single Track Seek Overlap

In a computer system where microcode is used to control the input/output devices, the system time required to transfer data (load) from a (low performance) disk storage drive having a removable disk to a (high performance) disk storage drive having a fixed disk and to transfer data (dump) from the high performance to the low-performance disk storage drive, is significantly reduced with minimal additional apparatus.

Load/Dump operations are basically sequential data moves, where data records are accessed on the basis of their successive physical locations in the file. The fixed disk storage drive is operated in the usual manner under microcode control, but the removable disk storage drive is started under microcode control and terminated by an index pulse. Hence, once the microcode starts the removable disk storage drive, it is free to operate the higher performance fixed disk storage drive.

In Fig. 1, all elements within the dashed line are used for nonoverlapped operation (multiple cylinder seek) of the removable disk storage drive. Only AND circuit 10, inverter 11, OR circuits 12 and 14 and latch 13 are added to provide the single track seek overlap. The single track seek is initiated by setting latch
13. This is accomplished via microcode which provides the proper combination of bits on bus 15 to AND circuit 10 which is gated by Command Sample on line 16, a signal initiated at the fall of Index Pulse on line 17.

Prior to the setting of latch 13, the microcode provides bits (bit 6 and 7) on Data Bus Out (DBO) for controlling the setting or resetting of latches 20 and 25, depending upon the direction of the seek. Movement of the disk storage drive transducer is under control of a stepper motor represented by block 40. Lines 41-44 inclusive lead to drivers for...