[ts-7000] PC104 16-bit confusion...

["richw42" <>]

I'm trying to understand how to do 16-bit transfers on the TS-7250
PC104 bus, but it doesn't seem to be happpening. Instead, I get two
cycles, apparently 8 bits each. The pair is a little faster, though.

When I run the program below, I see four cycles on each of IOR#,
MEMR#, IOW#, and MEMW#, with somewhat confusing (to me) signals on
BHE#. Here's what I see:

IOR# cycles
1 BHE#=0 A0=0
2 BHE#=0 A0=1
3 BHE#=0 A0=0
4 BHE#=0 A0=1

This is what I would expect, except for there being two cycles for the
16-bit transfer. By the way, A1 is always zero.

MEMR# cyces look about the same, except iirc faster.

IOWE# and MEMW# cycles:
1 BHE#=1 A0=0
2 BHE#=1 A0=1
3 BHE#=1 A0=0
4 BHE#=0 A0=1

This BHE# setting seems to make no sense.

What am I missing?

Here's the source code, with some comments and error checking removed:
(someone may recognize their code as my template)

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>

static volatile unsigned char  *pc104_io8;
static volatile unsigned short *pc104_io16;
static volatile unsigned char  *pc104_mem8;
static volatile unsigned short *pc104_mem16;

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

int main(int argc, char *argv[])
{
  int size = getpagesize();
  printf("Page Size = %d\n", size);

  int fd = open("/dev/mem", O_RDWR|O_SYNC);

  pc104_io8 =   mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
0x11E00000);
  pc104_io16 =  mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
0x21E00000);
  pc104_mem8 =  mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
0x11a00000);
  pc104_mem16 = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd,
0x21a00000);

  while (1) // Now once a second
  {
    char c;
    short s;
    sleep(1);
    c = *pc104_io8;
    c = *(pc104_io8+1);
    s = *pc104_io16;
    c = *pc104_mem8;
    c = *(pc104_mem8+1);
    s = *pc104_mem16;
    *pc104_io8 = c;
    *(pc104_io8+1) = c;
    *pc104_io16 = s;
    *pc104_mem8 = c;
    *(pc104_mem8+1) = c;
    *pc104_mem16 = s;
  }
}



 
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