Difference between revisions of "OMNIBUS"
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The OMNIBUS was physically implemented as a large [[backplane]], into which were plugged both the CPU, and the device controllers; device controllers did not have dedicated slots. | The OMNIBUS was physically implemented as a large [[backplane]], into which were plugged both the CPU, and the device controllers; device controllers did not have dedicated slots. | ||
| − | In [[analog]] electrical terms, it was very similar to the [[UNIBUS]]; mostly bi-directional [[transmission line]]s, with a few uni-directional control lines. The [[ | + | In [[analog]] electrical terms, it was very similar to the [[UNIBUS]]; mostly bi-directional [[transmission line]]s, with a few uni-directional control lines. The [[terminator]]s and [[voltage]] levels of the two were the same, and they shared driver and receiver circuitry. |
[[Category: DEC Buses]] | [[Category: DEC Buses]] | ||
Revision as of 18:26, 2 September 2018
The OMNIBUS is DEC's bus for the later PDP-8's; it was introduced with the PDP-8/E, in 1970. It provided three kinds of cycles:
- Programmed data transfers, in which the CPU reads or writes data to the device controller;
- Program interrupt transfers. in which the controller interrupts the CPU;
- Data break transfers, the PDP-8 term for DMA.
The OMNIBUS was physically implemented as a large backplane, into which were plugged both the CPU, and the device controllers; device controllers did not have dedicated slots.
In analog electrical terms, it was very similar to the UNIBUS; mostly bi-directional transmission lines, with a few uni-directional control lines. The terminators and voltage levels of the two were the same, and they shared driver and receiver circuitry.
