DOS ain't dead

uart interrupt tx rx in Dos32 bit open watcom (Developers)

posted by tom , Germany (West), 12.11.2013, 12:24
(edited by tom on 12.11.2013, 12:36)

I did that something like 20 years ago.
I remember that I needed several iterations until it worked reliable, it's MUCH easier to only use *receive* interrupts.
that said,

> When I try to send the first byte in the main, I receive the
> interrupt call, but when I send another byte there(in the interrupt), I
> don't receive the next interrupt call for the next byte to transmit.

most likely you don't read the status register (often enough)

pseudocode


void interrupt interrupt_service_routine()
  {

  for (;;){
    status = input(status_port);

    if (status & (tx_ready | rx_ready | overflow) == 0)
        break;

    if (status & tx_ready)
      if (more_characters_to_send)
        outport(dataport, next_character);

     if (status & rx_ready)
        buffer[next++] = inport(dataport);

     if (status & rx_overflow)
        transmission_errors++;
     }

    outport(0x20, EOI);   // only NOW acknowledge interrupt

   }


note: this was it AFAIR; no guarantees of any kind;)

Complete thread:

• uart interrupt tx rx in Dos32 bit open watcom - maui, 11.11.2013, 11:14 (Developers)
  • uart interrupt tx rx in Dos32 bit open watcom - RayeR, 11.11.2013, 19:34
    • uart interrupt tx rx in Dos32 bit open watcom - RayeR, 12.11.2013, 01:50
  • uart interrupt tx rx in Dos32 bit open watcom - tom, 12.11.2013, 12:24
    • uart interrupt tx rx in Dos32 bit open watcom - RayeR, 12.11.2013, 12:30
    • uart interrupt tx rx in Dos32 bit open watcom - bretjohn, 12.11.2013, 16:55
      • uart interrupt tx rx in Dos32 bit open watcom - maui, 12.11.2013, 19:23
        • uart interrupt tx rx in Dos32 bit open watcom - bretjohn, 12.11.2013, 21:12
        • uart interrupt tx rx in Dos32 bit open watcom - tom, 13.11.2013, 11:22
          • uart interrupt tx rx in Dos32 bit open watcom - maui, 13.11.2013, 15:49
            • uart interrupt tx rx in Dos32 bit open watcom - Oso2k, 13.11.2013, 22:26
              • uart interrupt tx rx in Dos32 bit open watcom - maui, 15.11.2013, 19:43
                • uart interrupt tx rx in Dos32 bit open watcom - tom, 16.11.2013, 19:02
                  • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 17.11.2013, 04:21
                    • uart interrupt tx rx in Dos32 bit open watcom - maui, 19.11.2013, 12:42
                      • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 19.11.2013, 20:59
                      • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 22.11.2013, 15:22
                        • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 23.11.2013, 03:09
                          • uart interrupt tx rx in Dos32 bit open watcom - maui, 24.11.2013, 13:45
                            • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 26.11.2013, 23:25
                              • uart interrupt tx rx in Dos32 bit open watcom - RayeR, 27.11.2013, 03:26
                                • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 05.01.2014, 20:42
                                  • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 26.01.2014, 02:06
                                    • uart interrupt tx rx in Dos32 bit open watcom - tom, 27.01.2014, 22:46
  • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 16.11.2013, 01:14
    • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 16.11.2013, 01:15
    • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 16.11.2013, 01:16
  • uart interrupt tx rx in Dos32 bit open watcom - Brian_extended, 16.11.2013, 01:32