On Nov 20, 20:35, LFessen106_at_aol.com wrote:
> They both have the PS2 KB port.. I tried an actual PS2 KB, it lit up as
> expected, but I got a no console error.. Do you think it will actually
use a
> PS2 KB and just needs to detect a mouse as well (with a PS2 splitter) or
the
> SGI PS2 KB/Mouse is proprietary? I did read somewhere that some SGI's
use a
> standard PS2 KB...
Indy, Indigo^2, O2, etc use a PS/2 keyboard (or a PC-AT keyboard with a DIN
to miniDIN adaptor) and PS/2 mouse, running at +5 volts. All the earlier
machines use one of several variants of a proprietary protocol/pinout,
basically RS423 running at +/- 8 volts or more.
>From the manual page:
The pin assignments for the DIN-6 keyboard connector on the CPU board
of
some of the newer systems are shown in the following table:
___________________________________
|_____KEYBOARD_CABLE_PINOUT_______|
|Pin | Signal | Description |
|____|________|___________________|
| 1 | KRCD | Keyboard Receive |
| 2 | MRCD | Mouse Receive |
| 3 | GND | Ground |
| 4 | +8Vdc | Power |
| 5 | KTXD | Keyboard Transmit |
|_6__|_-8Vdc__|_Power_____________|
For machines whose keyboards have the DIN-6 connector on the keyboard,
as well as on the CPU, the pinout is shown in the following table.
The
connectors on both sides of the keyboard have identical pinout, either
may be used for the mouse and the cable to the CPU.
__________________________________
| KEYBOARD CONNECTOR PINOUT |
|_________________________________|
|Pin_|_Signal_|_Description_______|
| 1 | KTXD | Keyboard Transmit |
| 2 | MTXD | Mouse Transmit |
| 3 | GND | Ground |
| 4 | +8Vdc | Power |
| 5 | KRCD | Keyboard Receive |
| 6 | NC | Not Connected |
|____|________|___________________|
The interface between the keyboard and the system is 600 baud
asynchronous. The format used is one start bit followed by eight data
bits, an odd parity bit and one stop bit, with one byte sent per key
up
or down transition. The MSB of the byte is a "0" for a downstroke and
a
"1" for an upstroke. Control bytes are sent to the keyboard with the
same speed and format. The system software does all the processing
needed to support functions such as capitalization, control
characters,
and numeric lock. Auto-repeat for a specified set of characters can
be
turned on or off by the system software by sending a control byte to
the
keyboard. When auto-repeat is enabled a pressed key will begin auto-
repeating after 0.65 seconds and repeat 28 times per second. The
keyboard initializes upon power-up. The configuration request control
byte causes the keyboard to send a two-byte sequence to the system.
The
second byte contains the eight-bit value set on a DIP switch in the
keyboard. All keyboard lights (if any; some newer systems have
keyboards
without user controllable lights) are controlled by the system
software
by sending control bytes to the keyboard to turn them on or off.
Control
bytes are also used for long and short beep control and key click
disable.
For the mouse:
Signals: The serial data interface signal level is compatible with
RS-423
which has roughly a 10V swing centered about ground. The idle state
and
true data bits for the interface are Mark level or -5V whereas false
data
bits and the start bit are spaces or +5V. The serial data is
transmitted
at 4800 baud with one start bit, eight data bits, and no parity.
Protocol: The mouse provides a five-byte data block whenever there is
a
change of position or button state. The first byte is a sync byte
which
has its upper five bits set to 10000 and its lower three bits
indicating
the button states where a 0 indicates depression. The sync byte looks
like this: 10000LMR. The next four bytes contain two difference
updates
of the mouse's change in position: X1, Y1, X2, and Y2. Positive
values
indicate movement to the right or upward. System software ignores
bytes
beyond the first five until reception of the next sync byte.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
Received on Tue Nov 21 2000 - 03:03:20 GMT