Blit (computer terminal)
Encyclopedia
In computing
, the Blit was a programmable bitmap
graphics
terminal
designed by Rob Pike and Bart Locanthi Jr. of Bell Labs
in 1982.
When initially switched on, the Blit looked like an ordinary textual terminal, although taller than usual: Similar to the VT100
it had an addressable cursor
and supported escape sequences. However, after logging into a Unix
host (connected to the terminal through a serial port
), the host could load (via special escape sequences) software onto the Motorola 68000
processor of the display. This software could make use of the terminal's full graphics capabilities and attached peripherals such as a computer mouse. Normally, users would load the mux windowing system, which replaced the terminal's user interface
by a mouse-driven windowing interface, with multiple terminal windows all multiplexed over the single available serial-line connection to the host.
Each window initially ran a simple terminal emulator, which could be replaced by a downloaded interactive graphical application, for example a more advanced terminal emulator, an editor, or a clock application. The resulting properties were similar to those of a modern Unix windowing system; however the interactive interface and the host application ran on separate systems—an early implementation of distributed computing
.
The Blit technology was commercialized by AT&T
and Teletype. In 1984, the DMD (dot-mapped display) 5620 was released, followed by models 630 MTG (multi-tasking graphics) in 1987 and 730 in 1989. The 5620 used a Western Electric
32000 processor and had a large green phosphor display with 800x1024 resolution (66x88 characters in the initial text mode). The 630 and 730 had Motorola 68000
processors and a faster 1024x1024 monochrome display (most had orange displays, but some had white or green displays).
The folk etymology for the Blit name is that it stands for Bell Labs Intelligent Terminal, and its creators have also joked that it actually stood for Bacon, Lettuce, and Interactive Tomato. However, Rob Pike's paper on the Blit explains that it was named after the second syllable of bit blit
, a common name for the bit-block transfer operation that is fundamental to the terminal's graphics. Its original nickname was the jerq, inspired by Three Rivers' PERQ
graphic workstation.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, the Blit was a programmable bitmap
Bitmap
In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...
graphics
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....
terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
designed by Rob Pike and Bart Locanthi Jr. of Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
in 1982.
When initially switched on, the Blit looked like an ordinary textual terminal, although taller than usual: Similar to the VT100
VT100
The VT100 is a video terminal that was made by Digital Equipment Corporation . Its detailed attributes became the de facto standard for terminal emulators.-History:...
it had an addressable cursor
Addressable cursor
In computing, an addressable cursor is a cursor which can, through use of either software or firmware, be moved to any given point on the computer screen...
and supported escape sequences. However, after logging into a 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...
host (connected to the terminal through a serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
), the host could load (via special escape sequences) software onto the Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
processor of the display. This software could make use of the terminal's full graphics capabilities and attached peripherals such as a computer mouse. Normally, users would load the mux windowing system, which replaced the terminal's user interface
User interface
The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...
by a mouse-driven windowing interface, with multiple terminal windows all multiplexed over the single available serial-line connection to the host.
Each window initially ran a simple terminal emulator, which could be replaced by a downloaded interactive graphical application, for example a more advanced terminal emulator, an editor, or a clock application. The resulting properties were similar to those of a modern Unix windowing system; however the interactive interface and the host application ran on separate systems—an early implementation of distributed computing
Distributed computing
Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal...
.
The Blit technology was commercialized by AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
and Teletype. In 1984, the DMD (dot-mapped display) 5620 was released, followed by models 630 MTG (multi-tasking graphics) in 1987 and 730 in 1989. The 5620 used a Western Electric
Western Electric
Western Electric Company was an American electrical engineering company, the manufacturing arm of AT&T from 1881 to 1995. It was the scene of a number of technological innovations and also some seminal developments in industrial management...
32000 processor and had a large green phosphor display with 800x1024 resolution (66x88 characters in the initial text mode). The 630 and 730 had Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
processors and a faster 1024x1024 monochrome display (most had orange displays, but some had white or green displays).
The folk etymology for the Blit name is that it stands for Bell Labs Intelligent Terminal, and its creators have also joked that it actually stood for Bacon, Lettuce, and Interactive Tomato. However, Rob Pike's paper on the Blit explains that it was named after the second syllable of bit blit
Bit blit
Bit BLIT is a computer graphics operation in which several bitmaps are combined into one using a raster operator....
, a common name for the bit-block transfer operation that is fundamental to the terminal's graphics. Its original nickname was the jerq, inspired by Three Rivers' PERQ
PERQ
The PERQ, also referred to as the Three Rivers PERQ or ICL PERQ, was a pioneering workstation computer produced in the early 1980s....
graphic workstation.
See also
- History of the graphical user interfaceHistory of the graphical user interfaceThe graphical user interface, understood as the use of graphic icons and a pointing device to control a computer, has a four decade history of incremental refinements built on some constant core principles...
- RioRio (program)rio is Plan 9 from Bell Labs's windowing system. It is most notably known for making its window management transparent to the application. This allows running rio inside of another window manager.-Design concepts:...
- 3B series computers, some of which also used the WECO 32000 processor, were often used with DMD 5620s
External links
- Bart Locanthi, Rob Pike: Blit (MPEG) (YouTube), the classic animated short about the windowing terminal project (it was necessary to explain how mice worked back then; this was 1982, two years before the MacMacintoshThe Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
) (MPEG) - Source code 5620