Messages in this thread | | | Date | Mon, 5 Aug 1996 18:30:58 +0000 (GMT) | From | Carlos A M dos Santos <> | Subject | Re: serial ports |
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On Mon, 5 Aug 1996, Magnus Hiie wrote:
> Why is it impossible for multiple (standard) serial ports (ttyS?) to > use the same IRQs? > > Is it some hardware limitation or what? When an interrupt occurs, > serial driver could look up which port it was meant for, couldn't it?
This is not a Linux limitation. It is due to the PC architecture. Some special "inteligent" cards can achieve this by mean of a special driver. Read the Serial-HOWTO, which stands
" The number of serial ports you can use is limited by the number of interrupts (IRQ) and port I/O addresses we have to use. This is not a Linux limitation, but a limitation of the PC bus. Each serial devices must be assigned it's own interrupt and address. A serial device can be a serial port, an internal modem, or a multiport serial board.
Multiport serial boards are specially designed to have multiple serial ports that share the same IRQ for all serial ports on the board. Linux gets data from them by using a different I/O address for each port on the card. "
Cheers
---- Carlos Augusto Moreira dos Santos casantos@conesul.com.br ConeSul Internet - Rua Felix da Cunha 705/504 - Pelotas, RS, Brasil Telefone/FAX (0532) 27-3107 WWW: http://www.conesul.com.br - Opinioes expressas sao minhas e as nao expressas sao dos outros -
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