Kenbak-1
Encyclopedia
The Kenbak-1 is considered by the Computer History Museum
and the American Computer Museum
to be the world's first "personal computer
" . Only 40 machines were ever built and sold. It was designed and invented by John Blankenbaker of Kenbak Corporation in 1970, and was first sold in early 1971. The system first sold for US$
750. Only around 10 machines are now known to exist worldwide, with various collectors. In 1973, production of the Kenbak-1 stopped as Kenbak Corporation folded.
Since the Kenbak-1 was invented before the first microprocessor
, the machine didn't have a one-chip CPU
but instead was based purely on discrete TTL
chip
s. The 8-bit
machine offered 256 byte
s of memory
(=1/4096 megabyte). The instruction cycle
time was 1 microsecond
(equivalent to an instruction clock speed of 1 MHz), but actual execution speed averaged below 1000 instructions per second due to architectural constraints such as slow access to serial memory .
To use the machine, one had to program it with a series of buttons and switches, using pure machine code
. Output consisted of a series of lights.
Computer History Museum
The Computer History Museum is a museum established in 1996 in Mountain View, California, USA. The Museum is dedicated to preserving and presenting the stories and artifacts of the information age, and exploring the computing revolution and its impact on our lives.-History:The museum's origins...
and the American Computer Museum
American Computer Museum
The American Computer Museum is a museum of the history of computing located in Bozeman, Montana, USA. It was founded in May 1990 by Barbara and George Keremedjiev as a non-profit organization. The museum was originally intended to have been located in Princeton, New Jersey, but the location was...
to be the world's first "personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
" . Only 40 machines were ever built and sold. It was designed and invented by John Blankenbaker of Kenbak Corporation in 1970, and was first sold in early 1971. The system first sold for US$
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
750. Only around 10 machines are now known to exist worldwide, with various collectors. In 1973, production of the Kenbak-1 stopped as Kenbak Corporation folded.
Since the Kenbak-1 was invented before the first microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
, the machine didn't have a one-chip CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
but instead was based purely on discrete TTL
Transistor-transistor logic
Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...
chip
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s. The 8-bit
8-bit
The first widely adopted 8-bit microprocessor was the Intel 8080, being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M operating system. The Zilog Z80 and the Motorola 6800 were also used in similar computers...
machine offered 256 byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
s of memory
Computer memory
In computing, memory refers to the physical devices used to store programs or data on a temporary or permanent basis for use in a computer or other digital electronic device. The term primary memory is used for the information in physical systems which are fast In computing, memory refers to the...
(=1/4096 megabyte). The instruction cycle
Instruction cycle
An instruction cycle is the basic operation cycle of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction requires, and carries out those actions...
time was 1 microsecond
Microsecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...
(equivalent to an instruction clock speed of 1 MHz), but actual execution speed averaged below 1000 instructions per second due to architectural constraints such as slow access to serial memory .
To use the machine, one had to program it with a series of buttons and switches, using pure machine code
Machine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
. Output consisted of a series of lights.
See also
- Datapoint 2200Datapoint 2200The Datapoint 2200 was a mass-produced programmable terminal, designed by Phil Ray and Gus Roche, announced by Computer Terminal Corporation in June, 1970...
, a contemporary machine with alphanumeric screen and keyboard, suitable to run non-trivial application programs.
External links
- KENBAK-1 Computer Article
- KENBAK-1 Computer – Official Kenbak-1 website at www.kenbak-1.net
- KENBAK-1 Series 2 – Official Kenbak-1 reproduction kit at www.kenbakkit.com
- Kenbak-1 Emulator – Online Kenbak-1 Emulator
- Kenbak-1 Emulator – Offline Kenbak-1 Emulator
- The Kenbak 1 - The first Personal Computer – At the Computer Museum of Nova Scotia
- Kenbak 1 – Images and information at www.vintage-computer.com
- Kenbak-1 video – Watch Kenbak-1 replica running a simple program at www.oldcomputermuseum.com
- Kenbak documentation at bitsavers.org
- KENBAK-uino Hardware-based Kenbak-1 Emulator
- Recreating the First PC article about KENBAK-uino at hackaday.com