tj@gpu.utcs.toronto.edu (Terry Jones) (12/15/88)
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tj@gpu.utcs.toronto.edu (Terry Jones) (12/15/88)
I have a situation where by I have lots of serial devices in my pc xt environment. These include a modem, a mouse, a printer and an EPROM programmer that all act like serial devices. Some of the serial ports/devices allow themselves to be set up as COM3 and COM4. Some of the software I have recognizes COM3 and COM4. Things still aren't prefect. 1) Interrupts: the 3 and 4 ports share interrupts with other ports. Am I mistaken in assuming that software dealing with these devices that take over the interrupt should first look to see if it is their device that interrupted and if not them pass the interrupt on to the next piece of code that uses the interrupt? Do programs do this? (Kermit from Columbia for example, mouse drivers maybe?) 2) There are a couple of location in memory where the addresses of the com ports in the system get loaded at boot time if the device is really there. I assume it is the bios POST that checks to see whether the ports live and if so places their addresses in ram for serial software to use. My machine doesn't seem to load these addresses correctly and I am wondering whether this is a BIOS problem? 3) Do IBM's COM3 and COM4 use the same addresses as the industry "standard" com3 and com4 ports that were out for a time before IBM supported more com ports? Anybody with some real knowledge on this?