Browse Prior Art Database

Cylinder Switching

IP.com Disclosure Number: IPCOM000042332D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03

Publishing Venue

IBM

Related People

Authors:
Peterson, RA Randolph, JC [+details]

Abstract

Multiple sector operations in direct access storage devices (DASDs) can cross a head or cylinder boundary. In the past, head switching has been performed by the DASD adapter, but cylinder switching has not been done. This is because the cylinder address includes address bits which are contained in the head address field. The address field (Fig. 1) has a one-byte sector address. The second byte contains the track address and two high-order bits of the cylinder address, and the third byte contains the lower-order bits of the cylinder address. Because of this particular format, cylinder switching is more complex. To switch a cylinder, the head address in the second byte is incremented and the cylinder bits in the third byte are incremented.