UniFlex
Encyclopedia
UniFLEX is a Unix-like
operating system
developed by Technical Systems Consultants
(TSC) for the Motorola
6809
family which allowed multitasking
and multiprocessing
. It was released for DMA
-capable 8" floppy, extended memory addressing hardware (software controlled 4KiB paging), Motorola 6809 based computers. Examples included machines from SWTPC
and GIMIX. On SWTPC machines, UniFLEX also supported a 20 MB
, 14" hard drive (OEM
'd from Century Data Systems) in 1979. Later on, it also supported larger 14" drives (up to 80 MB), 8" hard drives, and 5-1/4" floppies.
Due to hardware
limitations, main memory space for the UniFLEX kernel had to be smaller than 56 kB
(code + data). This was achieved by writing the kernel entirely in assembly language
, and by removing a few classic Unix
features, such as group permissions for files. Otherwise, UniFLEX was very similar to Unix Version 7
, though some command names were slightly different. There was no technical reason for the renaming. By simply restoring the Unix style names, a considerable degree of "Unix Look & Feel" could be established, though due to memory limitations the command line interpreter (shell) was less capable than the Bourne Shell known from Unix Version 7.
TSC never bundled a C
compiler
with UniFLEX for the 6809, though they produced one. But in the early 1980s a C language implementation became available as a 3rd party product (the "McCosh Compiler"). Using such a C compiler could establish source-level compatibility with Unix Version 7, i.e., a number of Unix tools and applications could be ported to UniFLEX - if size allowed: Unix on a PDP-11
limited executables to 64 kB of code and another 64 kB of data, while the UniFLEX limitation was approximately 56 kB for both, code and data together.
In the mid 1980s a successor version for the Motorola
68000 was announced. Though it removed the pressing space limitations, it was not commercially successful because it had to compete with source-code ports of original Unix.
The source code for UniFLEX and supporting software is available on the Internet. (The Missing 6809 UniFLEX Archive)
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
developed by Technical Systems Consultants
Technical Systems Consultants
Technical Systems Consultants was a US software company.Headquartered first in West Lafayette, Indiana and later moved to Chapel Hill, North Carolina, it was the foremost supplier of software for SWTPC compatible hardware, as well as many other early makes of personal computers...
(TSC) for the Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
6809
Motorola 6809
The Motorola 6809 is an 8-bit microprocessor CPU from Motorola, designed by Terry Ritter and Joel Boney and introduced 1978...
family which allowed multitasking
Computer multitasking
In computing, multitasking is a method where multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for...
and multiprocessing
Multiprocessing
Multiprocessing is the use of two or more central processing units within a single computer system. The term also refers to the ability of a system to support more than one processor and/or the ability to allocate tasks between them...
. It was released for DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
-capable 8" floppy, extended memory addressing hardware (software controlled 4KiB paging), Motorola 6809 based computers. Examples included machines from SWTPC
SWTPC
The U.S. company SWTPC started in 1964 as DEMCO . It was incorporated in 1967 as Southwest Technical Products Corporation of San Antonio, Texas...
and GIMIX. On SWTPC machines, UniFLEX also supported a 20 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...
, 14" hard drive (OEM
OEM
OEM means the original manufacturer of a component for a product, which may be resold by another company.OEM may also refer to:-Computing:* OEM font, or OEM-US, the original character set of the IBM PC, circa 1981...
'd from Century Data Systems) in 1979. Later on, it also supported larger 14" drives (up to 80 MB), 8" hard drives, and 5-1/4" floppies.
Due to hardware
Hardware
Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
limitations, main memory space for the UniFLEX kernel had to be smaller than 56 kB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
(code + data). This was achieved by writing the kernel entirely in assembly language
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
, and by removing a few classic Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
features, such as group permissions for files. Otherwise, UniFLEX was very similar to Unix Version 7
Version 7 Unix
Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s...
, though some command names were slightly different. There was no technical reason for the renaming. By simply restoring the Unix style names, a considerable degree of "Unix Look & Feel" could be established, though due to memory limitations the command line interpreter (shell) was less capable than the Bourne Shell known from Unix Version 7.
TSC never bundled a C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
compiler
Compiler
A compiler is a computer program that transforms source code written in a programming language into another computer language...
with UniFLEX for the 6809, though they produced one. But in the early 1980s a C language implementation became available as a 3rd party product (the "McCosh Compiler"). Using such a C compiler could establish source-level compatibility with Unix Version 7, i.e., a number of Unix tools and applications could be ported to UniFLEX - if size allowed: Unix on a PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
limited executables to 64 kB of code and another 64 kB of data, while the UniFLEX limitation was approximately 56 kB for both, code and data together.
In the mid 1980s a successor version for the Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
68000 was announced. Though it removed the pressing space limitations, it was not commercially successful because it had to compete with source-code ports of original Unix.
The source code for UniFLEX and supporting software is available on the Internet. (The Missing 6809 UniFLEX Archive)