blk (05/09/83)
This months Byte magazine answers all questions on adapting to RS232.
billw@sri-unix.UUCP (07/08/83)
#R:uwvax:-86000:sri-unix:19600001:000:1159 sri-unix!billw May 7 02:43:00 1983 This is random comments, not actually having a VIC: Having the hardware capability for RS232 interupts is not the same as having that capability supported by the current software. The hardware may be configured to allow interupts so that future software can use this as a feature, or so that the user can use them himself. interupts are probably necessary for communicating at higher speeds... [enabling non-maskable-interupts? What a strange concept]. The apple is an example of a system where the bus ad some io cards support interupts, but little software listens too them. as for rs232 voltage levels, the interface probably does not generate +/-12V To meet the spec, the voltages only need to be +/-3 V, and a dc converter to get -5 from +5 is quite simple (Intersil has put it on a chip and two caps...). It may not even do that. From personal experience, I can assure you that most terminals and modems are perfectly happy with 0/5V (If you ever build one of those SBCs, and the only thing that uses +/-12V is the RS232 circuits, just connect +5 to the +12v input, and ground the -12v input. You may save your self two power supplies!) BillW