brianw@microsoft.UUCP (Brian Willoughby) (09/22/89)
In article <127500045@tippy> emerrill@tippy.uucp writes: > >/* Written 9:02 pm Sep 14, 1989 by TSEMM@ALASKA.BITNET in tippy:apple */ >>Yes...It's me again. One quick question....Is there a AT code to put >>interupst for my DAtalink1200/2400 modem. What would happen if I used >>a card with the interups active in a program that dosen't need it? I am >>not very fond of opening up my computer 3 times a day to change the >>interrupts...... > >Just leave the interrupts activated full time. I also have a DataLink >2400--never even messed with the dip switches once! I just stuck it in >my IIgs and started up... That makes sense - most serial I/O chips have programmable settings for interrupts. The 6850 ACIA on the ancient Apple Comm Card does, and I'm sure that most other cards do too. The switch can only prevent interrupts by disconnecting the signal, but just because it is connected doesn't cause interrupts. Any software which doesn't use interrupts should not program the serial chip to generate them. Well, I said shouldn't, but there might be some program that does (I wouldn't know why). Also, the Apple keyboard RESET line is usually connected to the serial chip through the Apple bus, so even if you run software which uses interrupts, it crashes, and then you run software which DOESN'T use interrupts, you should be able to return the serial chip settings to the powerup default by pressing RESET (i.e. powering off should not be necessary). My point is that you should be able to enable interrupts and never touch the card again, if the software is written correctly and the serial chip has programmable interrupt enable. I'm basing this on my knowledge of a few popular serial chips, does anyone know if there are Apple cards that use serial chips which DON'T have programmable interrupts? (yuck) BTW, the AT codes are just ASCII sequences which a modem understands as commands. The serial chip which is transmitting these codes to the modem through RS-232 (or on board) does not pay attention to what it is transmitting (i.e. you can't disable serial chip interrupts with an AT code). The modem cannot change the mode of the serial chip, this must be done by writing command bytes to the serial chip command address. Brian Willoughby UUCP: ...!{tikal, sun, uunet, elwood}!microsoft!brianw InterNet: microsoft!brianw@uunet.UU.NET or: microsoft!brianw@Sun.COM Bitnet brianw@microsoft.UUCP