Harry's Magic Touch
Harry's Magic Touch
So, I re-inserted the ROMS.
And then I fired her up.
And then ...
... For no discernable reason in particular ...
It initialised the CPU.
TODAY IS A GOOD DAY. :D
Whilst it would have been nice to definitively identify a failed part I'm more than happy that it's working now.
All keys seem to be working and 31743 bytes free (same as Harry found). I have powered off for a few seconds and powered on a few times - still no problems !
I can't tell you how grateful I am to all of you for your input and enthusiasm. I have been humbled by the kindness of those who have given up their time to help without asking anything in return. This really has been an interesting thread and some fantastic ideas have come out of it. I have learnt more from you all in the last couple of weeks than I could ever have hoped.
DaveM, MikeS: Thanks for your suggestions about reading the ROMS and putting me in touch with Harry. I am going to start building an EPROM Reader / Writer for fun - when its done I'll post some schematics and links to source code if anyone's interested.
Tezza: The blog from your PET project was extremely helpful in understanding how to go about starting the troubleshooting process. Its amazing that after all these years this little computer still has the power to rekindle my interest in electronics and programming - I hope I can pass this fascination on to my kids ! Long live the PET !
Dwight: I'd like to build a diagnostic ROM at some point - this seems like a very interesting project ! I must learn to use a scope and get my head around how these old machines actually shuttle data around. Since the USB interface I have has a couple of analogue inputs I may even be able to build a USB oscilloscope project at some stage - it's amazing how we can make do with what we can find in a pinch !
Carlsson: Again thanks for the input and the kind suggestion of looking through your boards as an alternative option.
Harry: You are a gentleman and a scholar ! If there is ever anything I can do to return the favour please let me know.
And of course I am now going to treat my PET to a clean and post more pics. I'd like to connect a reset switch at some stage so I don't kill the screen while I'm playing !
I hope I can remain an active member of the Forum and contribute where I can - I'll be keeping a close eye on the posts and if there is ANYTHING I can do to help please let me know !