Dual keyboard (with thinkpad 560X)

Pavel Machek (pavel@bug.ucw.cz)
Sun, 27 Sep 1998 14:15:27 +0200

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Hi!

It is possible to connect two keyoards to one computer. (I'll describe
concrete steps to do this with thinkpad 560X, altrough it should work
on any PS/2-mouse-capable computer).

0. Modify kernel to always detect psaux device

--- clean//drivers/char/psaux.c Fri Sep 11 20:54:24 1998
+++ linux/drivers/char/psaux.c Fri Sep 25 12:04:17 1998
@@ -617,7 +617,7 @@
psaux_fops.release = release_qp;
} else
#endif
- if (aux_device_present == 0xaa) {
+ if (1 || (aux_device_present == 0xaa)) {
printk(KERN_INFO "PS/2 auxiliary pointing device detected -- driver installed.\n");
aux_present = 1;
} else {

1. Thinkpad: Turn trackpoint off, reboot for change to take effect,
wait for linux to come up, CONNECT PS/2 KEYBOARD WHILE UP & RUNNING.
2. killall gpm (in case it touches /dev/psaux)
3. try attached software, leds on keyboard should blink and strange
scancodes should appear as you press keys on secondary
keyboard. (You'll need r/w privileges to /dev/psaux).

Strange is that keycodes are _not_ normal PC scancodes (I pressed ESC
F1 F2 F3 F4

(76)(f0)(76)(5)(f0)(5)(6)(f0)(6)(4)(f0)(4)(c)(f0)(c)

: release is prefixed with f0 etc. I would like to know what these
are...

And now, what issues it brings up: It is possible to create 2-console
machine from normally available components: you take PC, keyboard,
ps/2 keyboard, VGA and MDA (or good-PCI-VGA + good-PCI-VGA), and you
are done. I think that it would be nice to support this -
unfortunately this needs heavy modifications to current input device
support...

Pavel

-- 
I'm really pavel@atrey.karlin.mff.cuni.cz. 	   Pavel
Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).
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#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <fcntl.h>


#include "/usr/src/linux/drivers/char/pc_keyb.h"


int kbd;
char translate[256];


void
send(char c)
{
  if (write (kbd, &c, 1)!=1)
    fprintf( stderr, "send: %m\n" );
}


unsigned char
input(void)
{
  unsigned char c;
  if (read (kbd, &c, 1)!=1)
    fprintf( stderr, "read: %m\n" );
  fprintf( stderr, "(%x)", (int) c );
  if (c == KBD_REPLY_ACK)
    fprintf( stderr, "==ACK" );
  if (c == KBD_REPLY_RESEND)
    fprintf( stderr, "==RESEND" );
  return c;
}


void die(char *s) { fprintf(stderr, s); exit(1); }


void
send_cmd( char c )
{
  do
    send(c);
  while (input() != KBD_REPLY_ACK);
}


void
leds( char c )
{
  send_cmd(KBD_CMD_SET_LEDS);
  send_cmd(c);
}


#define X( a ) fprintf(stderr, "\n" a );


void
main(void)
{
  int c;
  kbd = open( "/dev/psaux", O_RDWR );
  X( "Reseting keyboard..." );
  send(KBD_CMD_RESET);
  input();
  if (input()!=KBD_REPLY_POR)
    die("por expected\n");
  leds(1);
usleep(100000);


#if 0
  X( "Disabling keyboard..." );
  send_cmd(KBD_CMD_DISABLE);
  X( "Setting map mode..." );
  send_cmd(0xf0);
  input();
  send_cmd(0x01);
  input();
  leds(7);
sleep(1);
#endif


  X( "Enabling keyboard..." );
  send_cmd(KBD_CMD_ENABLE);
  leds(4);
usleep(100000);


  X( "Setting autorepeat..." );
  send_cmd(KBD_CMD_SET_RATE);
  send_cmd(0x00);
  leds(2);
usleep(100000);


  X( "Done.\n" );
  leds(0);
  while(1)
    input();
}


--+QahgC5+KEYLbs62--


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