I think I'll wire in a Plus/4 connector on to one connector to test the Plus/4 with the BASIC version... Sounds like it will work though. The Complete Commodore Innerspace Anthology has the B-128 I/O in registers it, will see if I can get my P-500 to cooperate and give me feedback as to what registers to use. "Hársfalvi, Levente" wrote: > > Hi! > > Larry Anderson wrote: > > > > There isn't one. This is a 6529 single port interface (data sheet on > > > funet). When you read that address, all 8 data lines are read. When you > > > write, all 8 data lines are written. > > > > That's like the PET then, the DDR on it does not do much in relation to > > this interface (on the VIC and 64 the DDR is very important)... so I'll > > just define an unused location in the BASIC example. > > In fact the 6529B works by the well known NMOS trick that probably most > Commodore people know well (some maybe even if just waken up from sleep > ;-) ). The NMOS outputs can't provide strong HI levels. The 6529B input > port always gives back the current state of the port lines. If you want > to use a line as input, first write '1' to the appropriate output bit. > Since the NMOS high outputs are weak, the outputs can be pulled low by > an external line. If something pulled the line low, the appropriate bit > in the data register will be 0. > -- 01000011 01001111 01001101 01001101 01001111 01000100 01001111 01010010 01000101 Larry Anderson - Sysop of Silicon Realms BBS (209) 754-1363 300-14.4k bps Classic Commodore pages at: http://www.jps.net/foxnhare/commodore.html 01000011 01001111 01001101 01010000 01010101 01010100 01000101 01010010 01010011 - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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