11 Apr
1998
11 Apr
'98
8:09 p.m.
John Rollins wrote:
Now that I think about it... Where does one find info
on designing ISA(or
MCA, or PCI, or NuBus, or...) boards? From the looks of most boards, the
actual hardware isn't that hard(unless you consider such fine wiring or PCB
design difficult like I do), it's programming something to get it to
work(which I suppose is pretty easy if you're a good programmer and know
what you're doing, also something I'm not...).
I wouldn't be surprised if the prototyping cards came with at least a pinout,
maybe more. Anyhow you could find one on the web, or one of the many PC
hardware reference books.
The IBM PC Technical Reference manual was useful as I recall, if you can find
one of those.
As for programming, you just need a C compiler that has low-level instructions
available, like for doing I/O port ins and outs. Interrupt handlers are more
difficult to write than simple polling routines. If OTOH the card is
memory-mapped rather than I/O based it's a simple matter of creating a pointer
to the beginning of the occupied space and then using offsets from there, and
you will be reading and writing "memory" locations on your board just as if it
was main memory. This kind of thing should be easy in both DOS and Linux. I
don't have a lot of experience yet, but I'm going to try some experiments with a
digital data acquisition card. It takes up a couple I/O ports, and you can read
the port to check status on the digital inputs, or write to another port to
change the state of the digital outputs.
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