Home Featured #68 Mike Maginnis’ Rev 0 Apple II

#68 Mike Maginnis’ Rev 0 Apple II

#68 Mike Maginnis’ Rev 0 Apple II

Hi, welcome to another episode of the Assemblies
podcast. I'' m Chris Torrence and also I have an unique visitor today It'' s Mike McGinnis from the open Apple
podcast as well as also go down three inches as well as Mike tell us Why we'' re below the actual unique guest is this revision absolutely no Apple II That nobody has had the ability to detect or deal with . Therefore we believed we would certainly give it a try today As well as if it doesn'' t job, after that you ' ll take it to KansasFest as well as we'' ll allowed John Morris Is that his name? Yeah, yeah, we'' ll allowed John Morris have a run of it because I hear he can fix nearly anything Anyhow As well as what'' s what ' s actually what
are the symptoms? Oh, so when we transform it on you ' ll obtain a screen full trash and the repeated warning No, I was you understand recognizing you the power it beeps when as well as after that mosts likely to the boot up series This is beeps over and over unless you hold the reset crucial down and also after that it gets peaceful And you release as well as it starts again.Well,.

we'' ll reveal you. All. So by the method, this is Identification number 5 zero two 5 so.
it'' s in the later run of the modification absolutely no I believe there were like six thousand.
made or something as well as the board number is Five two absolutely no 6. It does not have the initial power.
supply. I believe the majority of the components of the original other than a pair of the Dynamic RAM chips which I had to replace since when we.
drew them up from the board that the legs simply broke down So those are not initial, yet every little thing else is I believe.
Awesome. Yeah, allow'' s obtain started. All right. We'' ll plug it in as well as see what happens Nothing yet That'' s eco-friendly well, but does that appearance yeah,.

s it.Do you believe it'' s real screen? That'' s well I think possibly the video.
connection is a bit loosened back here I'' m uncertain that ' s interesting, but we hit the reset But that is
the Apple to be we. hold it down right it behaves as well as well I'additionally which I presume we ' ll see those soon We have the original drives.
that were bought for this thing And whether these these are connected in.
or not doesn'' t matter hmm when I release So Mike, exactly how did you get this machine It was a woman whose partner was someone like us.
and had a cellar loaded with things as well as he passed away As well as she didn'' t know what to do with any one of it and we ' re chatting like Cellar your dimension loaded with This stuff a deck equipment.He had.

like chess video games like digital chess stuff He was actually that just every she.
had no idea what it was what it was worth Or just how to get rid of it and you understand, he had passed away like the.
year approximately before so she was still quite damaged up about it And also she sort of simply sent me this list of like here'' s All the things that I located in the basement.
until now. Can you tell me what to do with it? So I assisted her sort things out clean it.
up get it on ebay.com and also get it out of there Which wow truly appreciated and.
as a thanks she offered me this amazing That'' s really trendy and among these drives here.
has actually got a really little identification number that was acquired like a pair months after this was So Yeah So did it did it ever function or she claimed it yet But you'' ve never in fact it did not function when I got it Okay, it was this has been sitting and also had.
been sitting in their cellar for fairly some time Yeah, so it might have resembled 30 years.
back was the last time it really appropriate yeah We first got rid of all of the chips from the board.
and after that cleaned the motherboard with a combination of 90% isopropyl alcohol along with some contact cleaner And also after that we likewise tried exchanging out all the chips from.
my Apple II plus, however absolutely nothing seemed to make a distinction Mike and also I are mosting likely to utilize a reasoning probe to.
attempt to evaluate a few of the pins on the Apple II board As well as this is a design LP 560 in case you'' re. interested and also what I'' ve done is I ' ve hooked this up to 5 volts from the Apple II as well as to do that
I just tied right into the bottom audio speaker pin. below, which is plus five volts and after that for ground I ' ve tied into the ideal most pin on.
the supporting video clip connector up here As well as you can see that I as opposed to attempting to connect the.
alligator clips straight to the pins and also a danger shorting them I'' ve simply utilized these little header.
wires here simply to make it a bit safer so if we take the logic probe and we just touch it to say the ground line on the 6502 You can see that it beeps and afterwards we can just go.
down the pins as well as examination to see which ones are working So for instance the following one.
here'' s the ready line.So that ' s high Here is the clock So both lights are illuminated and after that. it ' s blinking with a high pitch sound That means that it'' s a square wave that'' s. more than 200 kilohertz. That'' s excellent and then Let'' s go over to the various other side of the board right here Pin 40 on the 6502 is the reset.
line. So if I just hold that down Then I hit reset You can see it goes reduced And now it'' s back high once more Currently that I'' ve hit reset it ' s doing that point where it ' s. continually warning and also beginning over and also over once more and also once again So now we can see if we can figure out.
what'' s taking place from any one of these other pins So for instance pin 34 is the read-write line As well as you can see that each time it Does a reset then there'' s a change for the.
read-write line and afterwards below are the data pins for the 6502 So this is D0 D1 D2 D3 4 5 6 7 this is currently deal with line a 15 so this would certainly.
be the high bit of the address line To check all the solder pads on this Apple II motherboard I'' m going to try a technique.
suggested by Alan Environment-friendly on the Facebook web page As well as that was to lay down a piece of.
aluminum foil in addition to a soft towel and after that with the motherboard on top of it simply press the Favorable get in touch with on each pin as well as make certain that it makes.
contact with the solder pad on the bottom and I you can see I'' ve got the black lead linked to the aluminum foil and afterwards I'' m simply mosting likely to test each.
among these pins one after an additional To see to it that I'' m getting call All right, so right here'' s the rev no. Apple II looking significantly extra disheveled We didn'' t obtain it working Mike, what do you What do you need to claim? Well, we did a great deal of repairing at the very least as.
high as we know just how to do we did a lot of signal Checking out with your logic probe as well as The voltmeter still the same.
results we switched out the key-board Power supply our supply we.
drew RAM chips we reset stuff the CPU We recognize is functioning since we examined pin.
40 and also 37 and also obtained the ideal signals out of that Yeah, we know that we'' re getting some kind of vehicle beginning big some kind of auto begin because we when we placed the disc 2 card in slot 6 it does.
you understand the it tries to do the reset Yet yeah, I suggest, you recognize villages have been shed as well as Millions are dead and at least one Apple II plus.
over there got sacrificed to evaluate all this out, yet I Assume I think we'' re gon na need to delay to us Higher minds than ours.Maybe John will certainly have. some thoughts and also I ' m gon na head house now But I ' m leaving this here. He ' s surrendering. I appreciate your aid and a few of the concepts But ultimately we'' re still type of.
where we were prior to you power it up as well as You know, I mean still does the exact same point Alright, so Mike and I were.
incapable to fix his rev absolutely no Apple II So ideally following episode.
we'' ll have a fix for the issue and also Allow you know what occurred. Up until after that thanks for viewing If I see this on ebay.com.