28 Oct 2001 
M. K. Brewer

Ideas on LD/Linux Drivers Problems
----------------------------------

The fact that the OS always loads correctly from the DOS boot floppy,
plus the fact that it always loaded correctly using the previous
version of Rad Hat Linux, makes me suspicious that there may be
something going on with the current version of dosemu and Red Hat 7.1.
The loader program uses a delay routine to wait for the OS to load
before checking if it is running.  There is the possibility that
dosemu with Red Hat 7.1 isn't doing the delay correctly and the
resulting delays are too short.  Unfortunately, I can't find out
anything about how the delay function operates.  The program is
written in Borland C, which I don't have, and delay() seems to be a
Borland library function.  If you have Borland C, then you might try
writing a test program that reads the clock, calls delay(5000) for a 5
second delay, then reads the clock again and prints out the time
difference.  If the resulting delay is less than 5 seconds, you could
try increasing the delays in AT6400.C (the one written by compumotor,
not Petar's driver of the same name).  I suppose you could also go
back to the previous version of Linux (I beleive it was Red Hat 6.0)
and see if that solves the problem.

---

>From the source code:

 ER_ROMNORUN,            "time-out waiting for processor startup",
  /* card did not respond as expected - the card controller
     was programmed (indicated by the "[1]" printed to the
     screen by the downloader) and the processor does
     not appear to have started running, the green led on
     the back of the card should have turn on and stay on
     after the card controller is programmed, check if
     downloading to correct card address, check if their is
     another card in the PC that uses the same address that
     the card is set to (network card, etc.), try a fresh
     copy of the operating system from the diskette that
     was shipped with the card, if the green led on the back of
     the card flashes briefly (200ms) during an operating
     system download attempt (and none of the above suggestions
     work) the card may need repair, also if the green led
     on the back of the card turns on and stays on and this
     error message still occurrs, the card may need repair */
.
.
.

  lca_program();    /* Download AT6400 OS */
  delay(2000);  /* delay increased from 600 msec for compatibility with Pentiums */
  checkrunning();
.
.
.
void checkrunning(){
 if((inportb(basep+cstat) & 0x80) != 0)
  error(ER_ROMNORUN);
}

The change history is also pretty suspicious:

*****************************************************************************
 
 Revision History:
 
 Rev 1.0:  June 1990 Tom Hergenrother created.

 Rev 1.1:  06/16/92 T.H. disabled interrupts around writing to XILINX part.

 Rev 1.2:  01/27/93 T.H. upgraded for aux2, error codes described, added
      feature list retrievable from bootroms.
 
 Rev 1.3:  11/09/93 M.S.M. fixed quiet mode.
    01/20/93 M.S.M. increased time delay in checkrunning() from
      600 msec to 1000 msec for Pentiums.

 Rev 1.4:  09/15/94 M.S.M. increased time delay in checkrunning() from
      1000 msec to 2000 msec for 90MHz Pentiums.
    09/15/94 M.S.M. added 500 msec delay before exiting loader to
      allow AT6400 OS to initialize itself.

 Rev 1.5:  12/06/96 M.S.M. added 250 millisecond delay after reseting the
                    Xilinx part in lca_mode_program().  This fix was need
                    on Pentiums >= 133MHz.

****************************************************************************/ 

The fact that they keep increasing the delay means to me that it is
not a true delay using a BOIS call to the real time clock.  Most
likely it is some kind of delay loop that is processor speed
dependent.  This may be handled differently by dosemu than by DOS.