On Fri, Sep 29, 2017 at 7:55 AM, Francesco Messineo <email@example.com> wrote: > On Fri, Sep 29, 2017 at 7:05 AM, William Levak <firstname.lastname@example.org> wrote: >> On Thu, 28 Sep 2017, Francesco Messineo wrote: >> >>> On Thu, Sep 28, 2017 at 12:48 PM, Francesco Messineo >>> <email@example.com> wrote: >>> >>>> > >>> >> >> If you have an older PET (without CRTC) that has been upgraded to Basic 4.0, >> the jumpers may not have been set correctly. There are jumpers that >> control addressing of the ROMs. If they are not set correctly you will have >> addressing problems. Check the schematics for correct jumper settings. >> > > Yes, I was just going to check that. I've noticed the jumpers don't > match my 3032 (with older basic). The owner of this PET said it used > to work though, so I was assuming that the jumper were correct. > I will also change the timing resistor and tantalum capacitor on the > 555 reset circuit, I've noticed the reset signal isn't very well > behaved (it resets randomly and sometimes doesn't release the reset > line). I think the tantalum capacitor is shorting randomly to ground > or the 1M resistor is intermittent. > Old hardware sometimes has lots of faults. update: changing the UD8 socket, did bring the system to the basic prompt, with correct bytes free count. I then restored the two CAS resistors (I had lifted them to swap RAM banks) and now I have a completely black screen, not even the garbage screen if I remove the UD9 ROM :( Looks like I now have to debug the video signal path. This PET hates me I guess. Frank Message was sent through the cbm-hackers mailing listReceived on 2017-09-29 09:00:02
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