From: nowhere@never.at   
      
   On 16.06.2021 12:31, muta...@gmail.com wrote:   
   > On Wednesday, June 16, 2021 at 8:19:19 PM UTC+10, Joe Monk wrote:   
   >> Remember, COM ports are tied to IRQs. IRQ3/4.   
   >>   
   >> There are only 4 because thats all the 8250 UART could provide, and the   
   8259 PIC could only give up two IRQs.   
   >>   
   >> If you use a driver, such as a digiboard, then it could handle more via   
   software interrupt...   
      
   > The BIOS manufacturer can provide as many devices   
   > behind that interrupt as they want.   
      
   NO, because I/O-ports are real hardware and there are only four   
   port-addresses defined and reserved for COM1..4, windoze just fakes shared.   
      
   > The normal INT 14H is polled anyway, for read.   
   > Not sure if something depends on an interrupt   
   > for the write. But the manufacturer can share an   
   > interrupt or anything else they want to do.   
      
   NO, it seems you have not read anything about hardware so far.   
      
   INT 14h is/was an old BIOS function which almost nobody used.   
   the underlying IRQs (3/4/5/7/10/11 or APIC) mean real existing   
   ports were connected to PIC or APIC.   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
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