----- Original Message ----- From: "Christian Dirks" <Toast_r@IdeaLine.info> To: <email@example.com> Sent: Thursday, February 16, 2012 8:21 AM Subject: Re: A newly working Commodore 720 - many questions... >> Q7) The CBM-II PSU's all supply a 50/60hz signal from the PSU, which I >> think is just used for the TOD clock on the CIA. As I'm unlikely to find >> this on a modern PSU, is there a really simple way of generating this >> signal? >> > Can simply be generated with a schmitt-trigger like in the c64. > Take a look at the schematics at > http://zimmers.net/anonftp/pub/cbm/schematics/computers/c64/250469-rev.A-left.gif > how the signal for the cia pin 19 is generated. > For the schmitt-trigger (U23 in the schematics) a 74LS14 can be used. -- Unless you can find 9VAC or some other low voltage line frequency AC signal in an ATX PS somewhere, I don't think an 'LS14 would withstand 110/220V very well... ;-) Message was sent through the cbm-hackers mailing listReceived on 2012-02-16 17:00:12
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