William Levak wrote: > I can make no sense out of this message. > > 59460 refferred to in the original message is the 6522 timer. > 59406 referred to in this message is not connected to anything on any > PET. > 59424 is the IEEE data input. He probably meant 59456, i.e. $e840 VIA, Port B. (I know why I normally use symbolic names for pin names... :-) VIA PB5 has the mentioned Sync input, that is also connected to PIA#1, CB1 (should be $e813, 59411), to generate the system interrupt once a frame (see the RESET routine, it enables the CB1 interrupt). The other stuff is PIA#1, CA2 (should be $e811, 59409) that drives the "BLANK TV / -EOI" line (see http://www.funet.fi/pub/cbm/schematics/computers/pet/2001/320130-1.gif) and that, in early PETs, give that blinking when saving to disk, or the flash effects Jim mentioned. Later the "blank screen" feature for this output pin has been removed. Andre -- Email address may be invalid. Use "fachat AT physik DOT tu-chemnitz DOT de" ------Fight SPAM - join CAUCE http://www.cauce.org------Thanks, spammers... Andre Fachat, Institute of physics, Technische Universität Chemnitz, FRG http://www.tu-chemnitz.de/~fachat - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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