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IBM Operating System/2

Introduction
Memory
Shell
Hard Disk Support
DOS Compatibility Box
Version Overview
Diskette Contents
Product List

Content created by "Mr. Tahara" (mirror HERE and HERE). Edited by Tomáš Slavotínek. JP-EN translation by ChatGPT.

Introduction

Commonly known as "OS/2," this is the single-user, multitasking operating system co-developed by IBM and Microsoft as the next-generation OS to replace PC-DOS. In the USA, it was announced as a new generation OS for the PS/2, equipped with MCA. At this point, the only MCA machine announced in Japan was the 5570, so it was also released for Multistation use.

The 16-bit version 1.x used the i80286's protected mode. Version 2.0 transitioned to 32-bit, with the latest version being 4.5.

The versions that could be used with the Multistation line were 1.0 and 1.1. IBM wanted to encourage the transition from DOS to OS/2, but at the time, the i80286's processing power was insufficient, and the required hardware memory and disks were very expensive, leading to minimal adoption.

Memory

Supported up to 16 MB of memory. Although the minimum requirement was technically 2 MB, in practice, more was needed.

Shell

• Version 1.0 featured full-screen switching.
• Version 1.1 introduced the GUI Presentation Manager.
• From version 2.0 onwards, it changed to the Workplace Shell.

Hard Disk Support

The file system introduced HPFS starting from version 1.2; prior versions only used FAT. If it shares commonalities with DOS, the maximum partition size would be 32 MB.

According to the "Installation Guide," for the 5570, a 32 MB partition is automatically set, so it is likely that in versions 1.0 and 1.1, the partition size was also 32 MB.

DOS Compatibility Box

Using less than 1 MB of space, it could run one DOS software program. Due to limitations of the i80286, it was not possible to run multiple programs simultaneously. However, the lack of complete compatibility was one reason users hesitated to transition to OS/2.

Version Overview

SE and EE Versions

IBM had its own classifications; the extended (EE) version included the Communication Manager (SNA connection) and Database Manager (RDBMS, which corresponds to the current DB2). Extended versions were not available for OS/2 products from other companies.

Version 1.0

According to the "IBM Operating System/2 Related Software Installation Guide" (Apr 1988, 1st Ed.), it consisted of eight diskette sets, with a minimum required partition size of 7 MB. While this may seem small by today's standards, considering that KDOS was only two 2DD diskettes at that time, it likely gave the impression of requiring substantial capacity.

Diskette Contents

Installation Disks: A and B
OS/2 Disks: 1 to 6

Product List