Data General RDOS

Data General
Industry	Computer hardware, software
Founded	1968
Fate	Acquired by EMC Corporation in 1999
Products	RDOS (Real-time Disk Operating System), Nova and Eclipse minicomputers

The Data General RDOS (Real-time Disk Operating System) is a real-time operating system introduced in 1970. It was distributed alongside Data General's well-known Nova and Eclipse minicomputer product lines.

Overview

RDOS enables multitasking by managing up to 32 concurrent tasks (comparable to modern threads) across two processing states—foreground and background—within a 64 KB memory limit. Subsequent releases expanded support to include Data General's 16-bit Eclipse minicomputers.

A simplified variant, called the Data General Diskette Operating System (DG-DOS or DOS), eliminates the real-time foreground/background distinction but still allows multiple threads and supports multi-user Data General Business Basic. Another related OS, RTOS, is designed specifically for diskless systems. The RDOS version running on microNOVA-based "Micro Products" micro-minicomputers is occasionally referred to as DG/RDOS.

During the early 1980s, Data General replaced RDOS with the AOS family of operating systems, which includes AOS/VS and MP/AOS (the latter known as MP/OS on smaller hardware).

Commands

The RDOS/DOS command-line interface recognizes the following commands:

ALGOL
APPEND
ASM
BASIC
BATCH
BOOT
BPUNCH
BUILD
CCONT
CDIR
CHAIN
CHATR
CHLAT
CLEAR
CLG
COPY
CPART
CRAND
CREATE
DEB
DELETE
DIR
DISK
DUMP
EDIT
ENDLOG
ENPAT
EQUIV
EXFG
FDUMP
FGND
FILCOM
FLOAD
FORT
FORTRAN
FPRINT
GDIR
GMEM
GSYS
GTOD
INIT
LDIR
LFE
LINK
LIST
LOAD
LOG
MAC
MCABOOT
MDIR
MEDIT
MESSAGE
MKABS
MKSAVE
MOVE
NSPEED
OEDIT
OVLDR
PATCH
POP
PRINT
PUNCH
RDOSSORT
RELEASE
RENAME
REPLACE
REV
RLDR
SAVE
SDAY
SEDIT
SMEM
SPDIS
SPEBL
SPEED
SPKILL
STOD
SYSGEN
TPRINT
TUOFF
TUON
TYPE
VFU
XFER

Antitrust lawsuit

In the late 1970s, Data General encountered an antitrust legal challenge under the Sherman and Clayton Acts due to its practice of bundling the RDOS operating system exclusively with its Nova and Eclipse minicomputers. The competitor Digidyne attempted to obtain a license for RDOS to operate on its hardware clone, but Data General declined, invoking its bundling rights. In 1985, courts including the Ninth Circuit found against Data General in the case Digidyne v. Data General, ruling that confining RDOS usage solely to Data General machines was unlawful tying. The Supreme Court refused to review the decision, thereby affirming the requirement for Data General to license its OS to rival companies.

Data General was acquired by EMC Corporation in 1999.

External links