Apple IIe Platinum getting RAM error when Disk II card inserted

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Anovah's picture
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I could really use some help with this IIe Platinum that I received as a donation since it was displaying garbage on the screen. I swapped the 6502 chip with an older IIe (which I hope is okay for testing. I also noticed the existing chip just says 6502 making me wonder if this was a donor board). Anyways, it solved the problem of displaying garbage and boots fine and passes the self test, however when I try booting with a Disk ][ interface card, it starts exhibiting some odd symptoms including failing to engage the drive (the red light begins to turn on for a half a second before disappearing). Also the boot itself is very odd in that the "Apple ][" characters appear very slowly as if by one pixel at a time.

At this point the self test produces an error of "RAM 00100000" which obviously leads me to believe this is a RAM problem. Does that sound right to everyone else? If so, is there a way to isolate which chip it may be and where a good place to replace them would be? I'd really love to see this thing up and running and I don't mind some soldering but I can't seem to find anything about that error.

I appreciate it very much! Thanks!

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Anovah's picture
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Re: Apple IIe Platinum getting RAM error when Disk II card ...

My best guess is the chip at F8 but I'd really hate to guess at this.

ggb
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Re: Apple IIe Platinum getting RAM error when Disk II card ...

If it's a platinum IIe then it should have a 65C02 CPU.

Regards
GeoffB

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

I think I'm just going to swap out both ram chips.

Does anyone know what kind to get or a good place to get them?

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

I heard that you can pull them off of an Apple iigs motherboard.

But I do not know which chips.

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

A platinum IIe came with a 65c02, its possible the initilization routine in the rom contains 65c02 instructions. The 65c02 introduced new instructions that would probably make a 6502 processor mad. For example, that Disk Ii card is detected by the Autostart rom on the machine. The newer rom probably has 65c02 only instructions. Try the machine with a 65c02 and see what happens! I would also see what rom revision that board has, just to be on the safe side. Good lick!

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

gobabushka wrote:

I would also see what rom revision that board has, just to be on the safe side. Good lick!

There was only 1 rom version on the platinum //e units.

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

Keatah wrote:
gobabushka wrote:

I would also see what rom revision that board has, just to be on the safe side. Good lick!

There was only 1 rom version on the platinum //e units.

Correct. It was the Enhanced Apple IIe firmware. The difference is that the CD-EF ROM is in one physical chip whereas on all prior IIe models, there was a separate CD and EF chip.

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

reading this thread is amazing....

Anovah wrote:

I could really use some help with this IIe Platinum that I received as a donation since it was displaying garbage on the screen. I swapped the 6502 chip with an older IIe (which I hope is okay for testing. I also noticed the existing chip just says 6502 making me wonder if this was a donor board). Anyways, it solved the problem of displaying garbage and boots fine and passes the self test,

that part seems to indicate that the problem is NOT related any more with the mainboard....

if the first posting is correct then it seems
that the attempts are at the moment a bit too early prior asking some more questions...

Anovah wrote:

however when I try booting with a Disk ][ interface card, it starts exhibiting some odd symptoms including failing to engage the drive (the red light begins to turn on for a half a second before disappearing). Also the boot itself is very odd in that the "Apple ][" characters appear very slowly as if by one pixel at a time.

At this point the self test produces an error of "RAM 00100000" which obviously leads me to believe this is a RAM problem. Does that sound right to everyone else? If so, is there a way to isolate which chip it may be and where a good place to replace them would be?

It seems rather more that the problem is related to the interface......
If the interface or the disk drag down the powersource
or locks a databit line
that might cause such errors....

so up till now there are questions remaining unsolved:

Did you use this Disk II interface and the drive at another computer without errors
or
did you use components that came along with this computer and might be damaged ?

Or did you test this Interface and the drive at other computer without errors ?

Dependent to the answer of those questions you will be able to narrow down
if the problem is really located at the mainboard or rather more at the Interface or the drive.....

speedyG

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Anovah's picture
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Re: Apple IIe Platinum getting RAM error when Disk II card ...

gobabushka wrote:

A platinum IIe came with a 65c02, its possible the initilization routine in the rom contains 65c02 instructions. The 65c02 introduced new instructions that would probably make a 6502 processor mad. For example, that Disk Ii card is detected by the Autostart rom on the machine. The newer rom probably has 65c02 only instructions. Try the machine with a 65c02 and see what happens! I would also see what rom revision that board has, just to be on the safe side. Good lick!

Ah okay, a good recommendation then. I luckily have a IIe enhanced so I pulled a 65c02 from that and am unfortunately getting the same results. I'll keep using that chip for the remainder of testing though for the reasons you mentioned.

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

speedyG wrote:

It seems rather more that the problem is related to the interface......
If the interface or the disk drag down the powersource
or locks a databit line
that might cause such errors....

so up till now there are questions remaining unsolved:

Did you use this Disk II interface and the drive at another computer without errors
or
did you use components that came along with this computer and might be damaged ?

Or did you test this Interface and the drive at other computer without errors ?

Dependent to the answer of those questions you will be able to narrow down
if the problem is really located at the mainboard or rather more at the Interface or the drive.....

speedyG

Good questions sir! I indeed was able to use the interface and drive on a different IIe with complete success (it seemed to read and write just fine). To be on the safe side though, I pulled a separate working card and drive from another machine which exhibited the same problems when inserted into the platinum.

I tried turning it on with just the card inserted (no drive attached) and it seemed to boot fine and pass the self test. Once that cable and drive are hooked up though, it fails to boot to disk (goes directly to prompt) and it fails the self test with that RAM 00100000 error. If I try to PR#6 it just stalls out.

The power drag is weird and concerning to me which is why I'm not sure if I should believe the self test or not.

Just in case, I've been cruising eBay to see what kind of RAM is out there. I think the kind of chip I need is a 4126 64x4 but I think there are even different kinds within that (I know very little about chips obviously). This one auction looks close but I wonder if it's still the wrong kind.
http://www.ebay.com/itm/8-uPD41264C-DUAL-PORT-VIDEO-RAM-64Kx4-256x4-155-40ns-5V-0-4-DIP-24-DRAM-VRAM-/221594789095?hash=item33981424e7:m:mDXZfBiRIpdgA5b_TY1r5SA

Thank you for the help!

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Re: Apple IIe Platinum getting RAM error when Disk II card ...

After the fact that you may confirm the controller to be O.K.
my next question would be:
what do you call "the power drag to be wierd" ?

I do believe in fact that your track to the RAM Chip is the wrong rail....

In fact rather more i believe the IOU Chip to be damaged....
and thats really a big foul, because in fact that chip is a so called
"custom Chip" meaning, that it has been manufactured specially for
Apple Inc. and is not availiable on free market....

In case that this verifies - the only solution will be to get it salvaged from another
mainboard where you for sure know that something else has been damaged and this chip
survived remaining in working condition....

this probably can be verified by a test swapping in another chip from a known working mainboard.

speedyG

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Anovah's picture
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Re: Apple IIe Platinum getting RAM error when Disk II card ...

speedyG wrote:

After the fact that you may confirm the controller to be O.K.
my next question would be:
what do you call "the power drag to be wierd" ?

I do believe in fact that your track to the RAM Chip is the wrong rail....

In fact rather more i believe the IOU Chip to be damaged....
and thats really a big foul, because in fact that chip is a so called
"custom Chip" meaning, that it has been manufactured specially for
Apple Inc. and is not availiable on free market....

In case that this verifies - the only solution will be to get it salvaged from another
mainboard where you for sure know that something else has been damaged and this chip
survived remaining in working condition....

this probably can be verified by a test swapping in another chip from a known working mainboard.

speedyG

Aw nuts, the IOU chip will be a tough one. Hopefully I can find that down the road, I want to save as many of these machines as possible.

Yeah, the way the light just briefly comes on the drive and the way the logo slowly appears on screen (what I described as a power drain) seemed super weird but also the fact that it only occurs when using the controller card makes me think you are correct.

Thank you for helping me keep these old beasts going as long as possible. I saw an auction for some chips but it's literally twice as much as I would be willing to pay. Wish me luck! lol

http://www.ebay.com/itm/Lot-of-25-Pieces-Vintage-Apple-IIe-Integrated-Circuit-MMU-CPU-IOU-Rom-Chips-IC-/222322055911?hash=item33c36d5ae7:g:BEUAAOSw8w1YBujp