Browse Prior Art Database

Emulation of 8" Format for 5 1/4" Diskettes

IP.com Disclosure Number: IPCOM000061089D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Schreier, CP Trainor, DW Womeldorff, RA [+details]

Abstract

A method is provided for emulating the format for 8" diskettes for 5 1/4" diskettes by maintaining a consistent interface. The emulation is performed in a computer system where the operating system thereof issues FM (frequency modulation) 128-byte commands to the label area and the low-level microcode intercepts these commands and instead issues MFM 256-byte commands. This allows the diskette to conform to the recording standards by being 'all MFM' (modified frequency modulation). The 128-byte granularity of the computer operating system is maintained by padding 128 bytes onto each original diskette record. The first 128 bytes of each 256-byte sector contains the meaningful data. Implementing the microcode in this way produces a new format on diskettes.