ZEBRA (computer)
Encyclopedia
The ZEBRA was one of the first computers to be designed in the Netherlands, (the first one was the "ARRA
") and one of the first Dutch computers to be commercially available. It was designed by Willem van der Poel
of the Netherlands Post, Telegraph and Telephone, and first delivered in 1958. The production run consisted of fifty-five machines, manufactured and marketed by the British company Standard Telephones and Cables, Ltd.
The ZEBRA was a binary, two-address machine with a 33-bit word length. Storage was provided by a magnetic drum memory
holding 8 K-words; accumulators were also implemented as recirculating drum tracks in a manner similar to that used in the Bendix G-15
. Peripherals included paper tape reader and punch, and teleprinter.
(or I/O) address, and a 15-bit operation field
. Each bit of the operation field had a distinct meaning and could be used in nearly any combination, leading to many elegant tricks that today might be considered the domain of microprogramming.
Some bits made an instruction conditional on the accumulator state, as with the Zuse Z22 or Electrologica X1
.
Multiplication, division, square root, as well as all floating-point operations, were performed by subroutines, using the underlying serial computer
ALU primitives add, subtract, shift right, shift left, and increment.
Programming aids included the Normal Code (assembler), trace utility, a floating point interpretive system, the Simple Code, the Matrix Interpretive Scheme, and an Algol compiler.
Since a magnetic drum does not support random access, some time is lost waiting for an instruction or piece of data become available. In a poorly-written program, the average wait time could be half the drum rotation speed, but there were ways to reduce this. A notable feature of the ZEBRA was a meter that measured how much of the machine's time was spent in non-wait states; this was called the "efficiency meter." When running the floating-point interpretive system, the efficiency meter tended to show around 50%, but if prospective customers were visiting, a more efficient program could be loaded for demonstration purposes!
ARRA (computer)
The ARRA was the first Dutch computer, and was built from relays for the Dutch Mathematical Centre , which later became the Centrum Wiskunde & Informatica .It was designed and built by Carel Scholten and Bram Loopstra, and was finished in 1952...
") and one of the first Dutch computers to be commercially available. It was designed by Willem van der Poel
Willem van der Poel
Willem Louis van der Poel is a pioneering Dutch computer scientist, who is known for designing the ZEBRA computer. In 1950 he obtained an engineering degree in applied science at Delft University of Technology. In 1956 he obtained his PhD degree from the University of Amsterdam...
of the Netherlands Post, Telegraph and Telephone, and first delivered in 1958. The production run consisted of fifty-five machines, manufactured and marketed by the British company Standard Telephones and Cables, Ltd.
The ZEBRA was a binary, two-address machine with a 33-bit word length. Storage was provided by a magnetic drum memory
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
holding 8 K-words; accumulators were also implemented as recirculating drum tracks in a manner similar to that used in the Bendix G-15
Bendix G-15
The Bendix G-15 computer was introduced in 1956 by the Bendix Corporation, Computer Division, Los Angeles, California. It was about 5 by 3 by 3 ft and weighed about 950 lb . The base system, without peripherals, cost $49,500. A working model cost around $60,000. It could also be rented for...
. Peripherals included paper tape reader and punch, and teleprinter.
Programming
The ZEBRA instruction word consists of a 13-bit drum address, a 5-bit registerProcessor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
(or I/O) address, and a 15-bit operation field
Opcode
In computer science engineering, an opcode is the portion of a machine language instruction that specifies the operation to be performed. Their specification and format are laid out in the instruction set architecture of the processor in question...
. Each bit of the operation field had a distinct meaning and could be used in nearly any combination, leading to many elegant tricks that today might be considered the domain of microprogramming.
Some bits made an instruction conditional on the accumulator state, as with the Zuse Z22 or Electrologica X1
Electrologica X1
The Electrologica X1 was a digital computer designed and manufactured in the Netherlands from 1958 to 1965. About thirty were produced and sold in the Netherlands and abroad....
.
Multiplication, division, square root, as well as all floating-point operations, were performed by subroutines, using the underlying serial computer
Serial computer
A serial computer is typified by internally operating on one bit or digit for each clock cycle. Machines with serial main storage devices such as acoustic or magnetostrictive delay lines and rotating magnetic devices were usually serial computers....
ALU primitives add, subtract, shift right, shift left, and increment.
Programming aids included the Normal Code (assembler), trace utility, a floating point interpretive system, the Simple Code, the Matrix Interpretive Scheme, and an Algol compiler.
Since a magnetic drum does not support random access, some time is lost waiting for an instruction or piece of data become available. In a poorly-written program, the average wait time could be half the drum rotation speed, but there were ways to reduce this. A notable feature of the ZEBRA was a meter that measured how much of the machine's time was spent in non-wait states; this was called the "efficiency meter." When running the floating-point interpretive system, the efficiency meter tended to show around 50%, but if prospective customers were visiting, a more efficient program could be loaded for demonstration purposes!
External links
- The instruction set of the ZEBRA in detail
- Evolution of the ZEBRA
- De ZEBRA, de eerste computer van de RuG (in DutchDutch languageDutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
) - Marketing Literature
- http://bitsavers.org/pdf/stantec BitSavers document archive.