I shall report here briefly about projects in Holland. Briefly because the means of our country and the serious set-back due to the occupation made achievements in this field not as spectacular as elsewhere and also because I shall give part of my time to my colleague Dr. Kosten for a description of his traffic-machine. That there is a vivid interest in Holland is proved by the success of a symposium on Modern Computing Machines held in Amsterdam on the 14th of May 1949 under the auspices of the Mathematical Centre and the Dutch Physical Society. I shall restrict this review to two projects of relay-computers.
There is the ARCO-project (Automatische Relais Calculator voor Optische Berekeningen = Automatic Relay Calculator for Optical Computations) at the Laboratory for Optics of Delft Technical University under direction of Prof. Dr. A.C.S. van Heel, whereas Mr. W.L. van der Poel is responsible for the actual design. Although the machine is built mainly to perform calculations connected with ray tracing in optical lens-systems, the design is that of a perfectly general purpose machine apart perhaps, from the rather limited size of its internal storage. It uses binary scale, viz. thirty binals and a sign digit and fixed binary point but also natural numbers can be dealt with.
In the arithmetical operations which are automatically performed square rooting is included. This is only natural as its normal programme shall include a relatively high number of this operation. Further are most generally accepted features as e.g. conditional shift of control provided. Deconverting from binary into decimal scale is also an automatic operation. Some parts of the operation are automatically checked. Standard multicontact telephone relays are used throughout the machine. The circuitry is conventional but well planned, permitting an addition time of about 40 m.sec. and a multiplication of 1.2 sec. The storage consists of a dead storage on switches for fixed instructions and a small live storage on relays of 10 words. For input teleprinter tape is used, decimal numbers being automatically converted into binary ones. Output is performed by means of an electrical typewriter. The space taken by the machine proper is exceptionally small, viz. less than 40 cubic feet. Date of completion is expected to be the end of 1949.
The second project is the ARRA (Automatische Relais Rekenmachine Amsterdam = Automatic Relay Computer Amsterdam) in the Computation Section of the Mathematical Centre at Amsterdam, under my own direction, whereas Mr. B.J. Loopstra is responsible for the actual design. This machine is to perform calculations of any type. Its plans were greatly inspired by those of Dr. Booth's ARC, about which Miss Britten told us the other day, but major changes have been made. Thirty binary digits with fixed binary point are provided, but possibility of ganging exists as the least significant part of the product is kept (by actually shifting during the multiplication into the multiplier register while the multiplier shifts out). So arithmetic of high accuracy or with natural numbers can be performed. Automatic operations are in great lines the same as those specified in the Princeton-code. Standard high-speed relays are used. In addition to its electronic apparatus is used e.g. in counters and in three places of the arithmetic unit to avoid waiting time until chatter of the relays has died down, the signal being applied at the first contact of the relay to the grid of a valve which contains one or more relay-coils in its main circuit. This construction also reduces practically to zero the current drawn over these relay contacts. Relays and time are saved in some parts by sending information from one contact of a relay to the other one as a charge on a condenser connected to the change-over lever. Addition time is 15 m.sec. and multiplication time about 400 m.sec. (the zeros of the multiplier being dealt with faster than the ones). Internal storage is a magnetic drum with an average time of access of 10 m.sec. and a capacity of 256 words. Input, output and external store is performed by modified teleprinter apparatus. The machine is expected to be completed in 1950.
