|WikiProject Computing||(Rated Start-class, Mid-importance)|
Copied from Grant line
- When the Digital Equipment Corporation and its hardware designers conceived the UNIBUS, its capability to accept and interpret interruptions to the OS was highest on their list of things they wanted... so a four-level hardware interrupt scheme was born; the first in the minicomputer world.
- To accomplish this, they created the UNIBUS, and its hardware-interrupt scheme. To do this, however, wasn't exactly simple in that day and age of simple (and expensive) logic chips. So they decided that any peripheral card (or set of cards) could assert an 'interrupt' on one of four levels on the system bus (UNIBUS or UNIversal system BUS)... and the software would sort it out. Remember, there wasn't any 'microcode' in those early days...
- The bus lines delivering the interrupt signals had to get to the processor cards via the system bus; so what happened if you weren't using a bus slot? It happened often in those days, thanks to dedicated backplane slots.
- Enter the Grant Card; it was simply a bit of Printed Circuit card that allowd an interrupt to cross an unoccupied bus slot.
- That's not too accurate a description, butthanks for saving it!
- Atlant 12:56, 19 October 2006 (UTC) (Who was once, for about a decade, the engineer directly responsible for the ongoing maintenance of the Unibus specification.)
Is there a reason this article is in the past tense?
- The machines might be in museums (maybe some actually still in service too) but do not think any new models have been marketing in a decade or more. Are there sources for any recent products? So I think the past tense is deserved; this should be a mainly historical article, discussing the context of 1969 and how the Unibus innovated, its influence on subsequent technology, and how it contrasts with other options, etc. W Nowicki (talk) 23:09, 17 May 2011 (UTC)
The picture shows cards with 108 connectors visible (6 * 18), and I'm guessing another 108 on the back. Why is that? Is this three separate unibus connectors? I think it needs some explanation. Mnb20 (talk) 13:07, 12 October 2011 (UTC)