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K > KENBAK COMPUTER COMPANY > Kenbak-1     


KENBAK COMPUTER COMPANY
Kenbak-1

The Kenbak-1 is considered by many to be the world's first "Personal Computer." The Computer History Museum granted it this designation when they were still located in Boston in 1986. More specifically, the machine represents the first commercially available Von Neumann (stored program) computing device intended and priced for personal use.

John V. Blankenbaker designed the Kenbak-1 and marketed in the pages of Scientific American in 1971. The machine's name was taken from the middle of John's last name.

The Kenbak-1 was designed in 1970 and pre-dated microprocessors. The Intel 4004 (the worlds first microprocessor) was introduced in 1971. Instead of being microprocessor based the Kenbak-1 was built almost entirely from TTL components.

Unlike many earlier machines and calculating engines, the Kenbak-1 was a true stored-program computer that offered 256 bytes of memory, a wide variety of operations and a speed equivalent to nearly 1MHz.

Approximately 40 of these machines were built and sold before they were discontinued. The world just wasn't quite ready for personal computing and the Kenbak-1 lacked some critical capabilities (such as expandability and I/O) that were needed to foster the revolution. 14 are currently known to exist with few more likely to be discovered.

__________

Contributors: Erik Klein

Julian Skidmore (Manchester, UK) comments:
Although the Kenbak-1's oscillator is 1MHz, it's clock speed was half that at 500KHz and simple calculations show it must execute instructions at an astonishingly low rate 300 instructions per second or less. This is because:

1. Memory is 1024 bits of serial memory, so random access will take 512 cycles on average - 1000 access per second.

2. CPU registers are placed in main memory too, and a typical instruction involves reading/writing the program counter, the accumulator and the instruction itself. Thus a maximum 1000/3 = 333 instructions can execute per second.

Having said that, the architecture is impressive. It looks like a typical 8-bit CPU: with several registers, multiple addressing modes including indexed addressing and variable length instructions.


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Hello i have look voor de meeing of ADM.
Found it look this link
http://en.wikipedia.org/wiki/ADM

greetings Fred

          
Sunday 17th July 2011
Fred  (Holland)

Although the Kenbak-1's oscillator is 1MHz, it's clock speed was half that at 500KHz and simple calculations show it must execute instructions at an astonishingly low rate 300 instructions per second or less. This is because

1. Memory is 1024 bits of serial memory, so random access will take 512 cycles on average - 1000 access per second.

2. CPU registers are placed in main memory too, and a typical instruction involves reading/writing the program counter, the accumulator and the instruction itself. Thus a maximum 1000/3 = 333 instructions can execute per second.

Having said that, the architecture is impressive. It looks like a typical 8-bit CPU: with several registers, multiple addressing modes including indexed addressing and variable length instructions.

          
Sunday 1st July 2007
Julian Skidmore (Manchester, UK)

 

NAME  Kenbak-1
MANUFACTURER  Kenbak Computer Company
TYPE  Home Computer
ORIGIN  U.S.A.
YEAR  1971
END OF PRODUCTION  1973
BUILT IN LANGUAGE  None
KEYBOARD  Front panel keys only
CPU  None - TTL based logic
SPEED  approx 1 MHz
RAM  256 bytes of shift-register memory
TEXT MODES  None
GRAPHIC MODES  None
COLOrsc  None
SOUND  None
SIZE / WEIGHT  18
I/O PORTS  None
POWER SUPPLY  Linear
PRICE  $750 new





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