Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!cmcl2!floyd!vax135!ariel!hou5f!orion!houca!hogpc!houxm!ihnp4!ixn5c!inuxc!pur-ee!CSvax:Pucc-H:ac4 From: CSvax:Pucc-H:ac4@pur-ee.UUCP Newsgroups: net.micro.pc Subject: Re: wizards needed - RS232 card and interrupts Message-ID: <135@pucc-h.UUCP> Date: Wed, 22-Jun-83 22:41:07 EDT Article-I.D.: pucc-h.135 Posted: Wed Jun 22 22:41:07 1983 Date-Received: Fri, 24-Jun-83 12:01:05 EDT References: cvl.413 Lines: 20 The folks at IBM have hidden some cute tricks up their sleeves to handle their communications interrupts. Check the technical reference manual page D-48 (logic diagram) and you will note that they have used the auxilliary output "OUT2" from the modem control register to mask off the INTRPT line. If you don't set OUT2, you will get nothing! No mention of this appears in the section on programming the INS-8250 - just a regurgitation of the chip specs. You do need to worry about the 8259 interrupt controller. The asynch comm adaptor uses interrupt level 4. You must set the interrupt mask register to enable level 4 (set the bit=0). You must also acknowledge each interrupt in the interrupt request register using the "end-if-interrupt" signal for level 4. Good luck! Tom Putnam Purdue University Computing Center ...decvax!pur-ee!pucc-h:ac4 (317)494-1787