I/O System and Bus Architecture
The NORD-10 was equipped with a common bus system for all external devices. The bus system was divided into groups, and a great deal of effort had been made to ensure that no device would be able to jam the bus system in the case of malfunction. Each group had its own controller which in addition to functioning as an electronic switch for the bus system, could also change priority for the whole group. All interconnections between the cards were done with multilayer printed circuit backwiring boards, and all input/output interface had the same standard form. The system could therefore be extended or reconfigured by plugging in new or shifting around the existing interface cards. The position of the device interface in the card rack determined the interrupt priority of the device. In direct memory access transfers the device would send a "request". The CPU would answer with a "grant" signal, which would be passed from device to device until it came to the device which initiated the "request", and transfer to the memory could take place. When two or more devices request a DMA request simultaneously to the CPU had the highest priority. One memory cycle later the next DMA along the chain would be allowed to send data, and so on, until a higher priority device again sent a request. This meant that many DMA devices could use the same bus system at the full data transfer rate. It was not necessary to establish a "master-slave" connection. The transfer was one 16-bit word/850 nanoseconds, or 2.2MB/s.
The printed backplane of the I/O bus was modular in groups of 8 interface slots. Interfaces for mass storages as disk, drum, magnetic tape, etc., were built with one interface card to be plugged at the appropriate place in the bus system, the remaining control cards (6-7) were placed in one of the backplane modules.
Read more about this topic: NORD-10
Famous quotes containing the words system, bus and/or architecture:
“[Madness] is the jail we could all end up in. And we know it. And watch our step. For a lifetime. We behave. A fantastic and entire system of social control, by the threat of example as effective over the general population as detention centers in dictatorships, the image of the madhouse floats through every mind for the course of its lifetime.”
—Kate Millett (b. 1934)
“An actor rides in a bus or railroad train; he sees a movement and applies it to a new role. A woman in agony of spirit might turn her head just so; a man in deep humiliation probably would wring his hands in such a way. From straws like these, drawn from completely different sources, the fabric of a character may be built. The whole garment in which the actor hides himself is made of small externals of observation fitted to his conception of a role.”
—Eleanor Robson Belmont (1878–1979)
“Defaced ruins of architecture and statuary, like the wrinkles of decrepitude of a once beautiful woman, only make one regret that one did not see them when they were enchanting.”
—Horace Walpole (1717–1797)