Is the serial port RS232 known as "amiga builtin port" ?

The Amiga had both a Centronics parallel port (with a 25 pin female connector) and an RS232 serial port (with a 25 pin male connector). Both could be called a 'builtin port'.

Neither of these originated with the Amiga (ie, they were around before the Amiga). The RS232 port standard goes back to the teletype days.

The term 'Amiga builtin port' is ambiguous (it might even refer to the bus expansion port).

Thanks for the reply !

actually i wanted to have a look at the default ISR routine of the linux kernel for the 9 pin serial port found at the back of the cpu. I looked at the folder "/usr/src/linux-2.6.22.5-31/drivers/serial/" as well as the folder "/usr/src/linux-2.6.22.5-31/drivers/char/" to find the driver-cum ISR file for the above mentioned port ! There are so many files, I could'nt locate the one for the 9 pin serial port of the pc !

The file serial.c does'nt contain any ISR call i.e. (request_irq) !!

Kindly help !

The RS232 standard is a hardware standard (electrical characteristics, connectors, etc). There are many devices/ICs that implement variations of it, and each require different drivers.

The IBM PC XT originally used an 8250 UART (and a standard 25 pin connector), which was changed in the PC AT to the 16450 UART (and the familiar but non-standard 9 pin connector). Of course, this functionality is now embedded in motherboard chipsets, but the basic 8250/16450/16550 interface remains.

So if you are looking for linux serial port code for a PC, you would look in 8250.c and related files. These files cover several variations (for example, the 16550 chip implemented a 16 character buffer).