Search results
Results from the WOW.Com Content Network
IBM 1620 data processing machine with IBM 1627 plotter, on display at the 1962 Seattle World's Fair. The IBM 1620 was a model of scientific minicomputer produced by IBM.It was announced on October 21, 1959, [1] and was then marketed as an inexpensive scientific computer. [2]
The IBM 1620, the Data General Nova, the HP 2100 series, and the NAR 2 each have such a multi-level memory indirect, and could enter such an infinite address calculation loop. The memory indirect addressing mode on the Nova influenced the invention of indirect threaded code .
An early widespread implementation was available via the IBM 1620 of 1959–1970. The 1620 was a decimal-digit machine which used discrete transistors, yet it had hardware (that used lookup tables) to perform integer arithmetic on digit strings of a length that could be from two to whatever memory was available. For floating-point arithmetic ...
"One method of designing a slave memory for instructions is as follows. Suppose that the main memory has 64 K words (where K = 1024) and, therefore, 16 address bits, and that the slave memory has 32 words and, therefore, 5 address bits." [48] IBM 1620 CPU Model 1 (a decimal machine) System Reference Library, dated 19 July 1965, states:
Early computers that were exclusively decimal include the ENIAC, IBM NORC, IBM 650, IBM 1620, IBM 7070, UNIVAC Solid State 80.In these machines, the basic unit of data was the decimal digit, encoded in one of several schemes, including binary-coded decimal (BCD), bi-quinary and two-out-of-five code.
The access time ranges from 100ms to a maximum access time for model 2 of 800ms and 700ms for model 1. The 1405 model 2 disk storage unit has 100,000 sectors containing either 200 characters in move mode or 178 characters in load mode, which adds a word mark bit to each character. The Model 1 contains 50,000 sectors. [26]
The Computer History Museum's IBM 1620 restoration project tried to get copies of any records from the IBM archives. If you have any idea where this "extended memory" 1620 was and if it was a Model I or a Model II it would be very helpful.
Controlling the A20 line was an important feature at one stage in the growth of the IBM PC architecture, as it added access to an additional 65,520 bytes (64 KB − 16 bytes) of memory in real mode, without significant software changes.