Chris@USC-ECLB.ARPA (01/21/84)
From: Christopher Ho <Chris@USC-ECLB.ARPA> I have been trying to get interrupts to work on my Apple, with little success. I own an Apple ][ +, with Prometheus Versacard, Microsoft Z80 card, and Videoterm-compatible 80-column card. If I remove my 80-column card, I can get the continuously updating clock example in the Versacard manual to work, with reservations. When I set interrupts to occur every 60 seconds, occasionally the interrupt handler will "stick," and display several seconds consecutively, even though there is only supposed to be one interrupt every 60 seconds. If I set interrupts to occur once every second, my Apple spends most of its time apparently servicing the interrupts, as any keystrokes I make are only echoed after many, many seconds. When I re-insert my 80-column card, even when it is not activated, nothing at all works. If i switch to the 80-column display, I see that it flickers with horizontal snow travelling up and down at perhaps a rate of 10 Hz. Neither Videx nor Prometheus were extremely helpful when I contacted them for help; apparently Prometheus almost DIScourages use of interrupts. I would really like to get interrupts working, both for the real-time utility, and for the serial port applications. As far as I can see, it seems to be a hardware problem/incompatibility. Perhaps someone more versed in hardware could help? As I recall, someone from ISI brought this up to the net a couple of months ago (??). Please don't hesitate to answer. As I said, I would really like to get this working. If a satisfactory answer appears, I will summarize to the net. Chris Ho Usc-Ecl Consulting -------