Browse Prior Art Database

Comments, Queries and Debate: Early Dutch Computer Disclosure Number: IPCOM000129576D
Original Publication Date: 1988-Jun-30
Included in the Prior Art Database: 2005-Oct-06
Document File: 1 page(s) / 13K

Publishing Venue

Software Patent Institute

Related People

W. L. van der Poel: AUTHOR [+2]


Fagotstruat 18 2287 BD Rijswijk Holland

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 63% of the total text.

Page 1 of 1


Copyright ©; 1988 by the American Federation of Information Processing Societies, Inc. Used with permission.

Comments, Queries and Debate: Early Dutch Computer

W. L. van der Poel

Fagotstruat 18 2287 BD Rijswijk Holland

(Prof. van der Poel sent us the following comments on C. J. Fern's letter. -- Editor)

We indeed built ZERO (a name given afterwards to the 1951 machine) out of physical parts of PTERA, and it actually ran for several months before the parts were needed in the assembly of PIERA. It was not a 7~/2-instruction machine, however.

ZERO was in fact the first functional-bit-coded (or horizontally microcoded) machine. It had four independent bits used to determine:

A Whether the memory was used for control (A=O) or arithmetic (A=1) C Whether the accumulator was to be cleared I Whether the operand was to be inverted (made negative) S Whether the word was going to (S= 1) or from (S=O) the store

Clearly not every combination was useful. It does not make sense to fetch the instruction negatively, so only 7 useful combinations remained. But one could, in principle, give all 16 possible instructions.

The idea was taken over in the real successor of ZERO: the ZEBRA, of which some 60 copies were built after our design by Standard Telephones & Cables, Ltd. This machine had 15 independent functional bits and hence 215 potential instructions, of which at least one quarter were again useless.

During the de...