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This Apple IIe machine has some problems, to be sure. A lot of random characters and such. But I shouldn't see "Apple ][" on the boot screen, correct.? Possibly someone swapped in an Apple II plus ROM, perhaps? Self diagnostics sometimes inditcates a ROM or many bad ROMs. Sometimes indicates RAM. Often goes into monitor or freezes. When I get "]" prompt, I can do HOME command and it executes normally but does not clear the screen completely. I can run a simple program, 10 PRINT "HELLO" and it does run but usually prints out many wrong characters. Any advice would be appreciated.I bought this on eBay, years ago, and am finally getting around to working on it.Other details. It has a Zip II chip and I tried that in my working Apple II plus and it seems to function for the most part, except that it makes ADTPro not work with cassette audio.Thank you to this fine community!
Original IIe machines before Apple started enhancing them boot with Apple ][ on the screen. Once a machine is enhanced (new roms and 65c02 CPU), it will then show Apple //e on the boot screen. Your roms seem to have a 1982 copyright, so that would be original. I believe enhanced roms would have a 1984 copyright.
I have enhanced ROMS/65c02 on the way from ReActive Micro. We'll see if that improves things. Hoping to avoid desoldering RAM but I am prepared for that, too.
Apple ][+ ROMs won't fit in a //e. As has been said before, early "unenhanced" //e had a ROM that was similar (but not identical) to the ][+. It displayed "APPLE ][" instead of "Apple //e".
If you are getting random chars on the screen it is extremely likely you have at least one bad RAM chip. Try running the self test to see if it shows you which one.
ooo...Zip Chip. I'm jealous.
Makes sense. Last time I operated a IIe was 1984. When self test does run, it usually says RAM F8. Thanks again.
What cards are installed? Try removing all cards and do the self test.
Thanks for that suggestion, though.
There's a bit of a pattern to what you're seeing, and it's that the value of 0x40 /0x04 seem to be getting incorrectly set in some of the bad characters.
You'll likley be able to type all the characters and have them correctly display but not always so it's not likely the character ROM.
For example, the title line should say Apple ][ but we're seeing Appha Y[ check out the hex values for the letters:
'['
The letters without bit2 (bit2 = 4) set display correctly, but the ones where the bit should be set are incorrect. This is how a "stuck" bit would present.
Except the spaces characters with values x00 appears as $ which has a value 0f x04 and that's really the opposite of a stuck bit.
The same can be said of the Y (x79) instead of ] character (x3D where both a x40 was added to and x04 was subtracted from the value of ] character to produce a Y.
That may just be a coincidence, but maybe not.
When you see things like this, power, RAM or data lines are usual suspects, but then there's the zip which may make things more interesting.
It looks like the $ where spaces should be either gets worse or is dynamic and for me that would suggest power could be the problem because even bad RAM should be fairly stable. But with the zip, if clock singnals are bad or RAM is too slow crazy results could happen. Is the Zip a new addition?
If this was my system, I'd start with power and RAM but I'd also check a standard 6502 and see if anything changes.
Zip came with it. But I tried cpu from 2+ and got similar results. But perhaps that cou is too slow? I do have a a new one coming from RetroActive. But your points about power are interesting. When I did try to boot with floppy, it sounded very sluggish, a bit like a cold starting engine. Stronger at first but progressively weak. Capacitor drain maybe. And of course it didn't successfully boot from floppy. Thanks for your analysis. Will the 2+ power supply work? I can try that swap.
Swapped PSU and got same results. So looking more and more like RAM/ROM or perhaps Zip Chip. But the Zip seemed to function in the II+ without any issues other than making ADTPro not work properly with cassette ports. Down to waiting on parts from Jameco and RetroActive. I'll update here once I have anything new to report. Thanks all, for your assistance. Cut my teeth on TRS80 and Apple ][+. Then in, 2017, the retro bug hit me and I have been collecting, little by little. I tend to keep with items I have used personally but I make exceptions for cool factor.
It all works excpt the Apple //e and the NEC 286. I also have a Mac Cube and Mac Lampshade. I never used those back in the day, but they are cool. For me, anything Pentium or above, does not scratch my retro itch and I personally draw the line there, in terms of collecting.
Good test, as long as the swapped one is good. =)
I don't know much about the zip chip, so for me that's a remove it from the equaiton to keep things simple thing. Alwasy a good place to start, a clean plate. Srip eveyrthing out to just the supply and mother board then build out from there as things test out. If you can get the system to boot to the applesoft prompt you can do some basic memory testing. If memory pans out, start adding things back one at a time until things go south. From that you should be able to determine if it's a device or power.
I can't tell from the picutre if the $ are fading in/out or if that's just the CRT referesh and camera sync issue... could be that. Does you eye see those flicker between $ and space? If it does flicker, I'm not sure it's a RAM chip thing or signal problem. RAM is usually good or bad not good some time, bad other times. The latter for me would suggest more a singal/timing thing but that's also not a frirst place to look. Easiest would be swapping out the supply (done), then RAM. Since the system isn't crashing on boot it seems the ROMs may be fine (at least the regions used for booting).
The //e roms come with a 65c02, too. And also waiting for RAM chips. Sometimes some characters do flicker, yes. Inconsistent, though. The linked video was similar in some respects and he scoped all the address lines. I don't have that equipment but in the end he did //e enhancement, replaced RAM. Still wasn't good until he re-seated the IOU chip. I have re-seated everything, so now I wait for chips. Thanks, Jeff!
https://youtu.be/-EtwUO3tNK8?feature=shared
PXL_20240222_022822925.jpg