schmidtd wrote:
Michael J. Mahon wrote:The key is to get to the metal and bypass all the serial port firmware. If a 1MHz 6502 can drive an SSC at 115kbps, then a 2.8MHz 65816 shouldn't have any trouble driving an SCC at 57kbps. Polling is the key.The BBS sample code (see: http://www.apple2.org.za/gswv/a2zine/Utils/Z8530_SCCsamples_info.txt) seems to be using an interrupt routine, and clams to be able to run at 57kbps. But polling would be more compatible with ADT and ADTpro's 'architecture'.
Many years ago, I worked with an early IBM 360 with a quite complex interrupt protocol for (especially) the card reader and the printer. I found that a simple polling protocol could be used which, if double buffering was implemented, was faster in a copy loop than all but the most bizarre interrupt-driven protocol. Of course, I didn't have to worry about whatever else was going on... ;-) -michael New, faster SUDOKU v2.0 solver for Apple II's! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it's seriously underused."