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NuBus is a 32-bit parallel computer bus, originally developed at MIT as a part of the NuMachine workstation project, and eventually used by Apple Computer and NeXT Computer.

Available on old Apple Macintosh computers and on NeXT computers. Standard: IEEE 1196

NuBus was a considerable step forward compared to other interfaces of the day. At the time most computer bus systems were 8-bit, as were the computers they plugged into. However NuBus decided on a 32-bit interface because it was clear the market was headed in this direction.

In addition, NuBus was agnostic about the processor itself. Most buses up to this point were basically the pins on the CPU run out onto the backplane, meaning that the cards had to conform to the signalling and data standards of the machine it was plugged into (being little endian for instance). NuBus made no such assumptions, which meant that a NuBus card could be plugged into any NuBus machine, as long as there was an appropriate device driver.

And in order to select the proper device driver, NuBus included an ID scheme that allowed the cards to identify themselves to the host computer during startup. This meant that the user didnt have to configure the system, the bane of bus systems up to that point. For instance, with ISA the driver has to be configured not only for the card, but for the slot it is plugged into, any memory it needs, and the interrupts it uses. NuBUS required no such configuration, making it one of the first examples of plug-and-play architecture.

Row A

Pin Name Description
1 -12 V -12 VDC
2 -  
3 /SPV  
4 /SP  
5 /TM1  
6 /AD1 Address/Data 1
7 /AD3 Address/Data 3
8 /AD5 Address/Data 5
9 /AD7 Address/Data 7
10 /AD9 Address/Data 9
11 /AD11 Address/Data 11
12 /AD13 Address/Data 13
13 /AD15 Address/Data 15
14 /AD17 Address/Data 17
15 /AD19 Address/Data 19
16 /AD21 Address/Data 21
17 /AD23 Address/Data 23
18 /AD25 Address/Data 25
19 /AD27 Address/Data 27
20 /AD29 Address/Data 29
21 /AD31 Address/Data 31
22 GND Ground
23 GND Ground
24 /ARB1  
25 /ARB3  
26 /ID1  
27 /ID3  
28 /ACK  
29 +5 V +5 VDC
30 /RQST  
31 /NMRQ  
32 +12 V +12 VDC

Row B

Pin Name Description
1 -12 V -12 VDC
2 GND Ground
3 GND Ground
4 +5 V +5 VDC
5 +5 V +5 VDC
6 +5 V +5 VDC
7 +5 V +5 VDC
8 * Reserved ?
9 * Reserved ?
10 * Reserved ?
11 * Reserved ?
12 GND Ground
13 GND Ground
14 GND Ground
15 GND Ground
16 GND Ground
17 GND Ground
18 GND Ground
19 GND Ground
20 GND Ground
21 GND Ground
22 GND Ground
23 GND Ground
24 ** Reserved ?
25 ** Reserved ?
26 ** Reserved ?
27 ** Reserved ?
28 +5 V +5 VDC
29 +5 V +5 VDC
30 GND Ground
31 GND Ground
32 +12 V  

Row C

Pin Name Description
1 /RESET Reset
2 -  
3 +5 V +5 VDC
4 +5 V +5 VDC
5 /TM0  
6 /AD0 Address/Data 0
7 /AD2 Address/Data 2
8 /AD4 Address/Data 4
9 /AD6 Address/Data 6
10 /AD8 Address/Data 8
11 /AD10 Address/Data 10
12 /AD12 Address/Data 12
13 /AD14 Address/Data 14
14 /AD16 Address/Data 16
15 /AD18 Address/Data 18
16 /AD20 Address/Data 20
17 /AD22 Address/Data 22
18 /AD24 Address/Data 24
19 /AD26 Address/Data 26
20 /AD28 Address/Data 28
21 /AD30 Address/Data 30
22 GND Ground
23 /PFW  
24 /ARB0  
25 /ARB2  
26 /ID0  
27 /ID2  
28 /START  
29 +5 V +5 VDC
30 +5 V +5 VDC
31 GND Ground
32 /CLK Clock

 

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Source(s) of this and additional information: wikipedia.org and others, from Hardware Book, Karsten Wenke, Michael Van den Acker
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