Browse Prior Art Database

Control of Initial Program Load From Diskette

IP.com Disclosure Number: IPCOM000121113D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Bell, TG: AUTHOR [+3]

Abstract

This article describes a programming technique which allows control of Initial Program Loading (IPL) from an installed diskette drive. It permits the user to select IPL from a diskette containing a valid IPL record or from elsewhere. The selection mechanism is independent of the operating system (OS) hard file format; only a DOS-compatible diskette drive is required.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 90% of the total text.

Control of Initial Program Load From Diskette

      This article describes a programming technique which
allows control of Initial Program Loading (IPL) from an installed
diskette drive.  It permits the user to select IPL from a diskette
containing a valid IPL record or from elsewhere. The selection
mechanism is independent of the operating system (OS) hard file
format;  only a DOS-compatible diskette drive is required.

      An IBM PS/2* personal system unit provides the option to enable
and disable IPL from a diskette by inspecting a flag in a
non-volatile RAM (NVRAM) set by a utility.  This embodiment is a
workstation that has a requirement not to allow IPL from a distant
diskette when upgraded with a resident diskette drive.

      The selection mechanism is controlled by a newly architectured
byte structured in NVRAM at offset X'2D8' which is inspected by the
power-on-self-test (POST) microcode to determine whether to IPL from
the diskette with a valid IPL record or to ignore the diskette in the
diskette drive.  For example the particular code values used in this
embodiment are:
X'00' => IPL from diskette with valid IPL record
X'7F' => Ignore diskette with valid IPL record

      An IPL selection system utility is required and has been
written which allows user-toggling of the above byte by typing a
command and specifying the command option at the DOS command prompt.

      The utility is protected from illegal use in two ways. The
utility does...