# NuBus

Available on old Apple Macintosh computers and on NeXT computers.
Standard: IEEE 1196, "Nubus-A simple 32-bit backplane bus".
Texas Instruments owns the standard today.

(at the card)
(at the computer)

UNKNOWN CONNECTOR at the card.
UNKNOWN CONNECTOR at the computer.

## 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

## +5V

Power to slot; 2 amps per slot maximum continuous.

## +12V

Power to slot; 0.25 amps per slot maximum continuous.

## -12V

Power to slot; 0.1 amps per slot maximum continuous.

## -5.2V

Unused

## GND

Power return for +5V, +12V, and -12V

## RESET

Open collector signal; card should use to reset circuitry.

## SPV

Slot Parity Valid; asserted if card provides parity. Never asserted under Apple NuBus.

## SP

Slot Parity; odd parity of AD0-AD3 if SPV asserted.

## TM0 - TM1

Transaction modifiers.

## AD<31:0>

Address/Data bits 31 to 0.

## PFW

Power Fail Warning given 2ms before AC power is lost.

## ARB<3:0>

Arbitration bits 3 to 0; arbitrates system mastership.

## ID<3:0>

Geographical address 3 to 0; hard-coded to slot.

## START

Asserted to indicate an address on AD lines.

## ACK

Acknowledge of START cycle.

## RQST

Request; asserted to request bus mastership.

## NMRQ

Non-master request; used to signal an interrupt.

## CLK

Clock. Asymmetrical 10MHz clock; synchronous transactions on NuBus.

Contributor: | Joakim Ögren, Karsten Wenke, Michael Van den Acker, Godel?

Source: | Apple Tech Info Library 2194: Macintosh II NuBus Slots, Pinout at Apple TIL homepage

Copyright © The Hardware Book Team 1996-2004.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2002-01-10