The DASK was a vacuum tube machine based on the Swedish BESK design. As described in 1956, it contained 2500 vacuum tubes, 1500 solid-state elements, and required a three-phase power supply of at least 15 kW.
Fast storage was 1024 40-bit words of magnetic-core memory (cycle time 5 μs), directly addressable as 1024 full words or 2048 half-words. This was complemented by an additional 8192 words of backing store on magnetic drum (spinning at 3000 rpm). A full word stored 40-bit numbers in two's-complement form, or two 20-bit instructions.
In addition to two accumulators, the DASK had three index registers, which could be used to modify the address of most instructions. An instruction word consisted of 11 bits for an address, two bits for index register selection, and seven bits for the operation code and its modifiers.
Operations included addition and subtraction (56 μs), multiplication and division (364 μs), binary shift and bitwise conjunction.
Peripherals initially included 5-bit paper tape (400 cps read time) and teletypewriter (12 cps); magnetic tape and other peripherals were added later on.
"DASK ALGOL" (PDF). Archived from the original (PDF) on September 27, 2007. Retrieved May 15, 2007. https://web.archive.org/web/20070927225919/http://archive.computerhistory.org/resources/text/algol/ACM_Algol_bulletin/1060952/p3-naur.pdf ↩