9 pin D-SUB male connector at the Computer.
The SGI model 021-0004-0002 is the optical quadrature mouse supplied with pre-Indigo2 Silicon Graphics workstations, including Personal IRIS 4D systems. It uses a 9-pin D-SUB connector and reports X- and Y-axis movement as analogue quadrature signals (XA/XB and YA/YB) rather than serialised data. The mouse connects to the DB-9 port on the side of the SGI keyboard, not directly to a port on the system chassis. Power is supplied at +12 V and −5 V from the host, with three active-low button lines for left, middle, and right buttons.
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | VCC | OUT | +12 VDC |
| 2 | XA | IN | X-axis quadrature A |
| 3 | XB | IN | X-axis quadrature B/-5V |
| 4 | YA | IN | Y-axis quadrature A |
| 5 | YB | IN | Y-axis quadrature B/MTXD |
| 6 | LEFT | IN | Left button |
| 7 | MID | IN | Middle button |
| 8 | RGHT | IN | Right button |
| 9 | GND | - | Ground |
Notes
- Direction is Computer relative to Mouse.
- The mouse attaches to the DB-9 port on the side of the SGI keyboard; there is no dedicated mouse port on the system chassis for older SGI workstations using this interface.
- Movement is encoded as quadrature signals: XA/XB for the X axis and YA/YB for the Y axis. Pin 3 doubles as −5 V on some system variants; pin 5 doubles as MTXD (mouse transmit data) on some variants.
- Button signals (pins 6–8) are active low with pull-up to +5 V.
- This interface is not compatible with PS/2 or serial mouse protocols; connecting an incompatible device risks hardware damage.
Signals
- VCC — +12 V power supply from the host to the mouse.
- XA — X-axis quadrature signal, phase A; combined with XB to determine horizontal movement direction and distance.
- XB — X-axis quadrature signal, phase B; also used as −5 V supply on some system variants.
- YA — Y-axis quadrature signal, phase A; combined with YB to determine vertical movement direction and distance.
- YB — Y-axis quadrature signal, phase B; also used as MTXD (mouse transmit data) on some system variants.
- LEFT — Left mouse button; active low.
- MID — Middle mouse button; active low.
- RGHT — Right mouse button; active low.
- GND — Signal and power ground.
References
- IRIS Hardware Developer Handbook (mouse interface, Table 4-16) — Silicon Graphics, Inc.