'Cyclades/multiple serial port'
Peter L. Peres
On Tue, 7 Jul 1998, Pavel Korensky wrote:
The Z8530 data sheet is available.
In ten words, the driver maps the specific port that requires attention
onto the given (normal) IO address space of a single serial port using an
extra control register and then does IO as usual. When interrupts occur
they are flagged in an extra register(s) (two for 16 ports, one for 8),
that has a set bit for each port that needs service. Thus the CPU knows
what to map.
This is for '100% serial port compatible' cards.
RISC-based controllers sometimes map memory as IO and manage buffers by
themselves, or use packet-oriented protocols in fixed-size (FIFO sized)
bursts to talk to the CPU.
hope this helps,
You would still need to rewrite your driver if you wanted it to work with
Windows9x. Windows uses the VCOMM driver to handle serial ports, and it is
not capable of multiplexing one interrupt to multiple devices.
At 07:18 PM 7/7/98 +0000, you wrote:
>On Tue, 7 Jul 1998, Pavel Korensky wrote:
>> BTW, does anybody have some knowledge how works the drivers for these
>> multiport cards? I mean, if I have one card with 8 serial ports and
>> embedded processor, how the data are transferred to PC system. How PC knows
>> which byte of data is from which port ?
>> I am asking because I have a lot of Z8530SCC chips and I would like build
>> my own card (just for fun) and I don't want to write drivers. So, ideally
>> the card should be able to use drivers from let's say above mentioned
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