Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Programmable Arbitration Level for Floppy Disk Controllers

IP.com Disclosure Number: IPCOM000110084D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Klim, P: AUTHOR [+2]

Abstract

Described is a hardware logic implementation that provides a programmable arbitration (ARB) level for floppy disk controllers (FDCs) as used in personal computer (PC) systems equipped with the MICRO CHANNEL* (MC).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 82% of the total text.

Programmable Arbitration Level for Floppy Disk Controllers

       Described is a hardware logic implementation that
provides a programmable arbitration (ARB) level for floppy disk
controllers (FDCs) as used in personal computer (PC) systems equipped
with the MICRO CHANNEL* (MC).

      In prior art, PC direct memory access (DMA) operations required
that the FDCs compete for the MC bus by way of the ARB bus.  The
local ARB bus resided inside the DMA controller and had the fixed ARB
level 2.  The ARB level was not programmable and the default of ARB
level 2 could never be altered.  The concept described herein
provides an architecture that enables the diskette controller ARB
level to be programmable.  The architecture also maintains
compatibility with previous systems.  In addition, the concept
provides a means to exclude specific volumes from being loaded into a
register.

      The figure shows the architectural logic for the floppy disk
controller ARB level register.  To ensure compatibility with previous
systems, the floppy ARB level comes up at level two upon
power-on-reset.  Subsequently, it may be reprogrammed during power-on
system (POS) operations to any possible level other than level 15
(processor).  If an attempt is made to program ARB level 15, the
operation is ignored and the previously assigned ARB level is
retained.  A safety circuit was implemented for this purpose.

      The floppy ARB level register may be accessed by way of POS
r...