Date: Sat, 4 Apr 2020 20:47:27 +0200 From: Polytropon <freebsd@edvax.de> To: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Direct control of parallel port data lines Message-ID: <20200404204727.cd2a4042.freebsd@edvax.de>
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For an "external relay control unit", I need to activate certain lines of the parallel port. I wish to address the 8 output lines of the port. How is this done on FreeBSD? On DOS (not that DOS, the other one), it was quite simple. Depending on which parallel port you wanted to address, you simply needed to put the correct byte to a port whose address would be assigned to the parallel port you wanted to address (usually 0x378, 2nd one was 0x3BC, 3rd 0x278). In ye olde Borland C, you would then do: outportb(portnum, databyte); The "composition" of the databyte was easy: You could control each of the 8 output lines of the port by having their corresponding bit set or cleared, so for example 1 | 2 | 8 | 256 would be bits (and therefore activated lines) 1, 2, 4, and 8. The rule was simple: line n -> bit 2^n; And for the pins of the port: line n -> pin n+1 (D0 - D7). To each of the 8 lines, a 2 x 7400 + SF123 + relay unit was attached, and you could then control anything with the relays. (By cascading, you could get more than 8 output lines.) All this is a memory artifact from more than 30 years ago... it needs to be reactivated... ;-) Because Borland C here of course required "#include <dos.h>", it doesn't work on FreeBSD. What's the correct in FreeBSD equivalent here? If possible, I want to use C for this task. I checked "man ppc" and "man ppi", but I don't find their content convincing, probably not what I'm looking for. What am I _actually_ looking for? -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...
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