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Article #8 (419 is last): Newsgroups: freenet.sci.comp.atari.questions From: ae302 Subject: PARALLEL BUS Date: Sun Jul 30 08:52:50 1989 NEED HELP WITH INTERFACING TO MY 130XE. I HAVE BEEN READING MAPPING THE ATARIAND HAVE COME UPON REFERENCES TO A POLLING OF THE PARALLEL BUS BY THE OS AT COLD START. WHAT IS THE POLL LOOKING FOR? A HIGH AT PIN 1(EXSEL)? ALSO; IT MENTIONS THAT IT PLACES A HANDLER IN THE DEVICE HANDLER TABLES, WHAT IS THE DEVICE SPECIFICATION(I.E.; D:,R:...)? LAST ON THIS: WHERE CAN I FIND MORE INFO ON THE BUS? MAPPING THE ATARI MENTIONS A 4 PART SERIES ON THIS IN ANTIC:THESE I HAVE READ, BUT WANT MORE SPECIFIC INFO FOR THE 130XE. ALSO INDIRECTLY RELATED QUESTION: HAS THE OS FOR THE XE MACHINES BEEN RELEASED IN PRINT? I HAVE THE OLD OS LISTING,(800 VERSION), BUT IT IS NOT REAL USEFULL FOR THE XE'S. THANKS PETE HALLER ae302 ** Answered by JOHN SUCHY (aa271) on Sun Dec 6 14:17:25 1987 ** You don't say what you want to do with the parallel port. So I will answer first your stated question as well as I can, then what I hope is your actual need. When first turned on, the 8-bit Atari computer checks several things, in order: the function keys (START, SELECT, and OPTION) the SIO port for DOS the SIO port for an R: handler (if no DOS), and the parallel port. I believe that all it does for the parallel port is try to talk to it by turning on parallel port access (see D100-D1FF and D800-DFFF) to see if there is anything there to be used. Any device that uses the parallel port must include a custom handler and may use any NON-STANDARD label. The exception to this is ICD's MULTI I/O Board which loads in a Dn: handler to mimick a disk drive. The point is, if you want to create a parallel port device, you have to write your own handler. As to the XL/XE OS (Operating System, for those who don't know), it has not been directly released. Bits and pieces are available in "Mapping the Atari", the magazines, etc. You could also try your only gueranteed complete resource: Dis-assemble the OS--IN YOUR OWN COMPUTER! Both user groups have dis-assemblers for members' use. The best is probably Ian Carlstrom's Turbo Dis-assembler (CACE). Now, let me speculate that what you really want is some way to either control something with your computer or to sense real-world information. Several people have written articles on how to do this using the joystickN port(s). It is also possible to simply reserve one or more memory locations, "steal" them from memory, then just read and/or write to those locations without worrying about all the fancy handlers and other considerations. It just happens that I wrote an article on this for the December issue of the CACE newsletter. Good luck on your project. Your Co-sysop John E. Suchy aa271 Thanks for asking.