US 5,818,654 AGranted

Apparatus and process for managing defective headerless sectors

AssigneeSeagate Technology LLC

InventorsPrafulla B. Reddy, Jimmie R. Shaver, Sean R. Atsatt, Mark H. Groo, Timothy V. Gates, William K. Weberg

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Abstract

A memory medium has a plurality of tracks arranged in a plurality of sectors with each track sector having a format which does not include header fields identifying sectors or sector defects or defect management procedures. Track management apparatus identifies the track sector currently confronting a transducer; the track management being based on sector pulses (in the case of a dedicated servo system), or being calculated based on track information, an index pulse and data wedge information from previous wedges (in the case of embedded servo systems), or being derived from a lookup table. To accommodate sector defects, a defect bank contains the identity and type of each defective or spare sector. Defect management apparatus is connected to the defect bank and track management apparatus to indicate when the sector confronting the transducer is a defective or spare sector to halt data transfer to thereby skip the defective sector, or to generate an interrupt signal to the processor to transfer data between the processor and an alternate sector.

Claims30

Dependent claims

A method of managing transfer of data between a processor and transducer confronting a rotatable recording disc having a plurality of concentric data tracks arranged in a plurality of servo spokes and a plurality of data wedges separated by respective servo spokes, each data wedge containing a plurality of data sectors, the transducer being operable to transfer data between the respective data sector and a host system, at least some data sectors being split by a servo spoke into fragments such that respective fragments of a split data sector are in different data wedges, each track having a format characterized by an absence of sector identification and defect management data, each servo spoke providing a servo gate signal, the transducer confronting the disc and operable to transfer data between a sector of a selected track confronting the transducer and the processor, at least some data sectors on the disc being defective sectors, the method comprising:

a) providing a defect bank identifying sectors containing defects on the selected track of the disc confronting the transducer;
b) identifying the selected track;
c) identifying the data sector currently confronting the transducer by
i) identifying the number of bytes in each data wedge on the selected track of the disc,
ii) continuously incrementing a count of bytes through that data wedge containing the data sector currently confronting the transducer,
iii) incrementing a count of data sectors on the selected track,
iv) calculating the layout of data sectors in the data wedge containing the data sector currently confronting the transducer based on the identification of the selected track confronting the transducer, the data sector count and the byte count, and
v) identifying the data sector currently confronting the transducer based on the calculated wedge layout and the data sector count;
d) identifying a sector of the track matching a sector identified in the defect bank;
e) inhibiting transfer of data between the processor and the transducer if the data sector currently confronting the transducer matches a sector identified by the defect bank;
and
f) resetting the byte count when the byte count matches the identified number of bytes in the data wedge.

9 more elements

Apparatus for inhibiting data transfer between a processor and a transducer confronting a rotatable recording disc having a plurality of concentric data tracks arranged in a plurality of servo spokes and a plurality of data wedges separated by respective servo spokes, each data wedge containing a plurality of data sectors, at least some data sectors being split by a servo spoke into fragments such that respective fragments of a data sector are in different data wedges, each track being characterized by an absence of sector identification and sector defect data, each servo spoke providing a servo gate signal, the transducer confronting the disc and operable to transfer data between a sector of the track confronting the transducer and the processor, the apparatus comprising:

a defect bank identifying defective sectors in at least the track of the disc confronting the transducer;
means identifying the number of bytes in each data wedge on each track of the disc;
track management apparatus for identifying the layout of data sectors on a selected track, the track management apparatus including
a first counter for incrementing through a count of bytes in a current data wedge containing the data sector confronting the transducer,
a second counter, responsive to the first counter identifying a count equal to the number of bytes in a data sectors, to increment a count of data sectors on the track, and
wedge calculation apparatus responsive to the data sector count and to the byte count to calculate the layout of data sectors in the current data wedge;
compare logic operable in response to the wedge calculation apparatus to identify the data sector currently confronting the transducer;
and
defect management apparatus connected to the defect bank and the compare logic and operable to inhibit transfer of data between the processor and the transducer when the sector identified by the compare logic is a defective sector identified by the defect bank.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/869,041Filed 4 Jun 1997 · continuation
Priority: 13 Jun 1994
Granted: 6 Oct 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G11B 20/1883
Error detection or correction; Testing , e.g. of drop-outs: methods for assignment of alternate areas for defective areas
G11B 27/3027
On the same track as the main recording: used signal is digitally coded
G11B 2020/1234
Sector, i.e. the minimal addressable physical data unit: wherein the sector is a headerless sector, i.e. it does not comprise an ID field
G11B 2220/20
Record carriers by type: disc-shaped record carriers