From: muta...@gmail.com   
      
   On Tuesday, April 4, 2023 at 12:12:33 AM UTC+8, wolfgang kern wrote:   
   > On 03/04/2023 17:37, muta...@gmail.com wrote:    
   > ...   
   > > I've written a serial port driver before, for the 8086.    
   > > It wasn't a lot of code.   
      
   > which pins of the 8086 CPU did you use to become RS232 ?   
      
   It's still for an 8086, even if it drives a UART.   
      
   C:\devel\pdcomm>grep Int 'pdcommd*'   
   pdcommd.c:     /* Interrupts 0-7 use the PIC at 20H, whilst interrupts 8-15 use   
   pdcommd.c:     uartDisableInts(&pdcomm->uart);   
   pdcommd.c:     pdcommdaInstallInt((long)pdcomm->vector * 4);   
   pdcommd.c:     /* switch of Interrupts */   
   pdcommd.c:     uartDisableInts(&pdcomm->uart);   
   pdcommd.c: /* pdcommInt is the interrupt handler */   
   pdcommd.c: void DOSPREF pdcommInt(void)   
   pdcommd.c:     id = uartGetIntType(&pdcomm->uart);   
   pdcommd.c:                 uartDisableInts(&pdcomm->uart);   
   pdcommd.c:         id = uartGetIntType(&pdcomm->uart);   
   pdcommda.asm: pdcommInt equ _pdcommInt   
   pdcommda.asm: pdcommdaInt equ _pdcommdaInt   
   pdcommda.asm: pdcommdaInstallInt equ _pdcommdaInstallInt   
   pdcommda.asm: extrn pdcommInt: far   
   pdcommda.asm: extrn pdcommInt: near   
   pdcommda.asm: extrn pdcommInt: proc   
   pdcommda.asm: public pdcommdaInt, pdcommdaInstallInt   
   pdcommda.asm: pdcommdaInt proc   
   pdcommda.asm:         call pdcommInt                  ;Note Could be small   
   stack   
   pdcommda.asm: pdcommdaInt endp   
   pdcommda.asm: pdcommdaInstallInt proc, address: dword   
   pdcommda.asm:         mov word ptr[bx+2],seg pdcommdaInt   
   pdcommda.asm:         mov word ptr[bx],offset pdcommdaInt   
   pdcommda.asm: pdcommdaInstallInt endp   
   pdcommda.h: void DOSPREF pdcommdaInstallInt(long address);   
      
   C:\devel\pdcomm>   
      
      
   > > Can e.g. the serial port be dual-driven by either a memory    
   > > write or an IO to cover both?   
      
   > sure possible, but why both ?    
      
   So that you can make a laptop that can have either   
   sort of CPU put onto the FPGA that is inside the laptop.   
      
   > and be aware that serial ports have more than one address.    
      
   Ok, I'm not sure what is required or whether a single dead   
   laptop is possible.   
      
   BFN. Paul.   
      
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