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 .
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.
With the System/370-XA architecture and the IBM Enterprise Systems Architecture, in addition to a 24-bit addressing mode for compatibility with older applications, there is a 31-bit addressing mode, in which only the high order bit (bit 0) in the word is ignored for addressing. An exception is that mode-switching instructions also use bit 0.
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...
In the 360/65 and 360/67, IBM introduced a concept known as prefixing. [2] Prefixing is a level of address translation that applies to addresses in real mode and to addresses generated by dynamic address translation, using a unique prefix assigned to each CPU in a multiprocessor system.
The term fixed-block architecture was created by IBM in 1979 [3] to distinguish this format from its variable-length record format. Each track is divided into fixed-length blocks, consisting of an ID field and a data field. Application programs refer to blocks by relative block number, and cannot address them by cylinder, head and record.
In computer hardware, a word mark or flag is a bit in each memory location on some early variable word length computers (e.g., IBM 1401, 1410, 1620) used to mark the end of a word. [1] Sometimes the actual bit used as a word mark on a given machine is not called word mark , but has a different name (e.g., flag on the IBM 1620, because on this ...