Disk track emulation system and method

Claim 2

A disk track emulation system as claimed in claim 1, wherein a track on said disk device includes a home address area for recording home address data for indicating at least the position of the track, and a count area provided for each record in said track for indicating the physical position of the record, said physical cell position data and said logical cell position data being written in said home address area and said count area.

Claim 3

A disk track emulation system as claimed in claim 2, wherein said logical cell position data is not influenced by damaged position data on said disk device.

Claim 4

A disk track emulation system as claimed in claim 1, wherein: during the control of a disk device, a process is carried out by using said physical cell position data; and during a transfer of data to said host device, a process is carried out by using said logical cell position data.

Claim 5

A disk track emulation system as set forth in claim 4, further comprising: checking means for checking damaged position data transferred, as the physical cell position data, from the host device during writing data into a disk track; writing means for writing the data, when a defect exists at a data writing position, by skipping the writing position on the disk track by a predetermined number of cells, based on said damaged position data (SC); and adding means for adding the number of cells for said skipping to the physical cell position data (PCN) indicating the current position on the disk track; whereby the position of the defect is corrected.

Claim 6

A disk track emulation system as set forth in claim 4 or 5, further comprising: take out means for taking out, when data is written on the disk track, written-data length data included in the count area sent from the host device; and adding means for adding the number of cells of the data area of this data and the number of cells of a gap thereafter to the logical cell position data ( LCN); whereby the position of the last logical cell when said data is written is calculated; and as a result, when exceeding the cell position of a physical index indicating the and of the physical track in the active format, the host device is informed of an error and said data is not written.

Claim 7

A disk track emulation system in a disk control device, for maintaining a compatibility between different data formats, said disk control device being connected between a host device and a disk device, said host device handling data in accordance with a first data format, and said disk control device and said disk device handling data in accordance with a second data format different from said first data format, the data in accordance with said first data format including, for each track on said disk device, a first home address indicating at least a logical position of the track and a first count area indicating at least a logical position of a record in the track, the data in accordance with said second data format including, for each track on said disk device, a second home address indicating at least a physical position of the track on said disk device and a second count area indicating at least a physical position of a record in the track, said first data format and said second data format being divided into a plurality of units of cells, such of said units consisting of a predetermined number of bytes, wherein: said second data format further including a physical cell position data indicating the physical cell position on said disk device to be accessed, and a logical cell position data used in said host device and indicating the logical cell position of said disk device to be accessed and corresponding to said physical cell position.

Claim 8

A disk track emulation method for maintaining a compatibility of a data format of a new disk track with an active data format, by using a new disk device having disk tracks with a data format different from that of an active disk device, and by means of a disk control device for controlling the new disk device, characterized in that: using the characteristic that said data format is divided by a unit called a cell having a constant number of bytes; and writing, into a home address area and a count area in the new data format, cell position data with the new data format, and compatible cell position data with respect to the active data format in which the compatibility should be maintained; whereby the compatibility of the data format is maintained.

Claim 9

A disk track emulation method as set forth in claim 8, characterized in that: using a physical cell position data as said cell position data of the new data format; using as said compatible cell position data a logical cell position data (LCN) determined, without influence by damaged position data, in accordance with the active data format; processing, during the control of a disk device (3), by using said physical cell position data (PCN); and transferring data to the host device by using said logical cell position data.

Claim 10

A disk track emulation method as set forth in claim 9, characterized by that: checking damaged position data transferred, as physical cell position data, from the host device while writing data to a disk track; writing data, when a detect exists at a data writing position, by skipping the writing position on the disk track by a predetermined number of cells, based on said damaged position data; and adding the number of cells to be skipped, to the physical cell position data indicating the current position on the disk track; whereby the physical position data is corrected with respect to the damaged position.

Claim 11

A disk track emulation method as set forth in claim 9 or 10, characterized in that: taking out, when data is written on the disk track, written-data length data included in the count area sent from the host device; and adding the number of cells of the data area of this data and the number of cells of a gap thereafter to the logical cell position data ( LCN); whereby the position of the last logical cell when said data is written is calcutated; and as a result, when exceediing the cell position of a physical index indicating the end of the physical track in the active format, the host device is informed of an error and said data is not written.