----- Original Message ----- From: "Jeri Ellsworth" <firstname.lastname@example.org> To: <email@example.com> Sent: Wednesday, October 25, 2000 1:28 PM Subject: Re: TOD on CIA > > ----- Original Message ----- > From: Steve Judd <firstname.lastname@example.org> > To: <email@example.com> > Sent: Wednesday, October 25, 2000 9:28 AM > Subject: Re: TOD on CIA > > > > Hola Nicolas, > > > > On Wed, 25 Oct 2000, Nicolas Welte wrote: > > > > > William Levak wrote: > > > > > > > > It has two 6522's and a 6526. > > > > VIA1 $1800-180F serial bus > > > > VIA2 $1C00-1C0F drive mechanism > > > > CIA1 $4000-400F fast serial bus > > > > > > > > > > I think the TOD input of the 1571 CIA is just not connected to anything. > > > > Is the AC line hooked up to the 1571 CIA? (Just speculating...) > > > > -Steve > > I looked at how the 1571 is powered and it is 12v and 5v DC only. > Please excuse me for jumping in (I just subscribed and hav'nt read prior to this---YET!) Wanted to add some 8520 info that may be relevant to your 6526: An AC mains frequency signal of 50 or 60 HZ is coupled to pin 19 of the 8520. On the A500, Pin 19 is direct connected to Vertical Sync. ~50-60 HZ In the A1000, 2000, and 3000 models, this timebase is from the AC mains. (Rumored to syncronise video with flourescent light flicker) Mains freq AC goes thru an optical isolator, and is buffered with a 7414 schmitt trigger to correct TTL level. This signal is a direct connection to the TOD clock in the A1000. The timebase source for A2000 and 3000 models can be either the AC signal, or Vertical Sync selected with a jumper. The other pin 19 input, on the other CIA, is connected to Horizontal sync, ~15.75Khz on the above models. So perhaps the Pin 19 YOUR discussing really is a clock input. Or else it should be pulled high right? Now, what the heck all you talking about anyway? 8-) > Jeri > > - > This message was sent through the cbm-hackers mailing list. > To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
Archive generated by hypermail 2.1.1.