RTFPS(4) NetBSD Programmer's Manual RTFPS(4) NNAAMMEE rrttffppss - multiplexing serial communications interface SSYYNNOOPPSSIISS rrttffppss00 aatt iissaa?? ppoorrtt 00xx11223300 iirrqq 1100 ccoomm22 aatt rrttffppss00 ssllaavvee 00 ccoomm33 aatt rrttffppss00 ssllaavvee 11 ccoomm44 aatt rrttffppss00 ssllaavvee 22 ccoomm55 aatt rrttffppss00 ssllaavvee 33 DDEESSCCRRIIPPTTIIOONN The rrttffppss driver provides support for IBM RT PC boards that multiplex to- gether up to four RS-232C (CCITT V.28) or RS-422A communications inter- faces. Each rrttffppss device is the master device for up to four ccoomm devices. The kernel configuration specifies these ccoomm devices as slave devices of the rrttffppss device, as shown in the synopsis. The port specification for the rrttffppss device is used to compute the base addresses for the ccoomm subde- vices. FFIILLEESS /dev/tty0? SSEEEE AALLSSOO com(4) HHIISSTTOORRYY The rrttffppss driver was written by Charles Hannum, based on the aasstt driver. BBUUGGSS The rrttffppss driver is unlikely to work on non-EISA and non-PCI machines. The ISA bus only asserts 10 I/O address lines, and this is not enough. Even on EISA and PCI machines, some address conflicts have been observed. On one machine, the second port always conflicted with something (though it's not clear what) and caused strange results. Disabling the second port in the kernel config allowed the other three ports to function cor- rectly. NetBSD 1.0 August 7, 1994 1