knudsen@ihwpt.UUCP (mike knudsen) (12/19/86)
Larry -- I tried to post this but inews is busted here today. Hope this helps. > I need some details about interfacing to a CoCo. I have built > an IEEE488 interface decoded at address ff60. The interface works fine Bravo! IEEE488 will help move Coco into labs, factories etc. And double bravo for using a "legal Coco-III" address FF60. > 1. Is there any way for an interface to be enabled in any slot of an > expansion box, regardless of the selected slot? (My speech/sound pack seems Yes. Instead of depending on the CTS- strobe to activate your pack, do the entire address decode (all 13 or so bits for FF6x) yourself. Then any slot will work. For safety, your pack should always assert the "phantom" lead (I forget its real name) when it detects its own address, to keep the Coco or MPI from selecting anything else. > 2. If the slot must be selected thru software, are there standard rules > for selecting slots? Well, sort of. Disk always goes in slot 4, and OS9 demands RS232 pack in slot 1. Beyond that you're on your own. Of course your software can prompt the user for which slot the IEEE pack is in, or get it off the OS9 command line. > 3. How is the SLEND line used? Is it a wired-or configuration? Oops on me, I think this is the Phantom lead. Yes it is wire-ORed. Pulling it down disables the demux chip in the Coco which distributes strobes to everything else. I suggest using it (see above). > 4. How are interrupts used from the expansion connector? How does OS9 > expect to see interrupts? The multipak (actually the side connector itself) supports only FIRQ, not IRQ. OS9 Version 2 (not Level II) tries to help by letting you use the 17 ms timer interrupt on IRQ as a "virtual" interrupt VIRQ -- sort of an automatic polling that your device driver can pretend is a real interrupt. > Thanks in advance. > Larry Harmon You're welcome -- mike k (Delphi: Ragtimer) -- Mike J Knudsen ...ihnp4!ihwpt!knudsen "It's like trying to get to sleep at the Intergalactic Spaceport Hotel -- waiting for the being in the room above to drop the Nth shoe, and you don't even know what N is."