dano@ssc-vax.UUCP (Dan Olson) (03/18/90)
Some questions regarding the parallel port on the Amiga and the 8520 chip. I am building a device that needs to be written to and read from. 1) Is there anyway for a device on the parallel port to know whether it is being written to or read from with only a read or write to the 8520 port B? According to my old hardware docs, it says that data ready (PC pin) will be brought low on any port B access, so how can I tell if it's a read or write? 2) When acknowledge (FLAG pin) is pulsed, is it only used for generating an interrupt, or will it also cause port B to latch what's on its pins? 3) If the port B is driving the parallel port data lines, is it a no no for a device on the port to pull any of these data lines to ground? (Writing to the parallel port when the device connected to it has data on the pins). For maximum compatability with AmigaOS I'd like to use the parallel.device for accessing my device. Any insight on how it handles the parallel port would be appreciated. I assume it reads or writes new bytes on acknowledge interrupts. How fast can the parallel.device respond to an interrupt? Thanks for any help. -- Dan Olson (UUCP ..!uw-beaver!ssc-vax!dano)
valentin@cbmvax.commodore.com (Valentin Pepelea) (03/22/90)
In article <3257@ssc-vax.UUCP> dano@ssc-vax.UUCP (Dan Olson) writes: > >1) Is there anyway for a device on the parallel port to know >whether it is being written to or read from with only a read or >write to the 8520 port B? I don't think so. >2) When acknowledge (FLAG pin) is pulsed, is it only used for >generating an interrupt, or will it also cause port B to latch >what's on its pins? It merely generates an interrupt. >For maximum compatability with AmigaOS I'd like to use the >parallel.device for accessing my device. Any insight on how it >handles the parallel port would be appreciated. I assume it reads >or writes new bytes on acknowledge interrupts. How fast can the >parallel.device respond to an interrupt? The 1.3 parallel.device reads and writes about 6000 bytes per second. The tranfer is not biderectional. Matt Dillon came out with a parallel.device replacement which allows two Amigas connected together to communicate bidirectionally as if they were using the serial port. Valentin -- The Goddess of democracy? "The tyrants Name: Valentin Pepelea may distroy a statue, but they cannot Phone: (215) 431-9327 kill a god." UseNet: cbmvax!valentin@uunet.uu.net - Ancient Chinese Proverb Claimer: I not Commodore spokesman be