Apple IIe Bad RAM

[InsaneDavid]

Continuing with my poor luck with Apple II's since getting rid of "mine" years and years ago, the Enhanced IIe I picked up last week has run into a problem.

This morning it refused to boot properly so I ran the system test and came back with a bad RAM 1 0 0 0 0 0 0 0 error. (Bad first RAM chip on the right) Not jumping to any conclusions I opened the case, made sure everything was tight, and the error went away. I proceeded to use the computer for a few hours without incident.

Later this evening I went to resume my Tass Times in Tonetown game and upon bootup I was met with gibberish text on the screen. A reboot returned the same. Attempting to boot directly to the command prompt resulted in gibberish as well and incorrect keyboard functionality. Booting to the system test (holding solid apple upon startup) gave the same bad RAM error as earlier. To eliminate a keyboard problem, a powerup with the keyboard disconnected (automatically runs system test) resulted in the same RAM error. On occasion a different RAM error would pop up (usually showing the first chip failing the test in addition to others). Although it would seem kind of random, at least 70% of the test failures would give me bad RAM 1 0 0 0 0 0 0. Inspecting the board revealed nothing obvious so I'm assuming I have some bad RAM, as the tests indicate.

My question is this: Is this the usual output given when Apple II RAM chips bite the dust? I mean the gibberish and whatnot, or is there something ahead in line that could cause the problem? I figure if it was anything hardcoded that was failing, booting from the disk drive would override it. Because I get errors regardless of boot method and can't even get a command prompt without problems, I'm assuming that the RAM isn't properly getting filled with data.

Second question: Are these here a proper replacement for Apple IIe RAM chips? As far as I see that's what I need. I'm also going to socket them this time around.

Any help would be great, thanks!

[crazzywolfie]

bad memory can cause a computer to crash or not boot at all. it can also make your computer run unusually slower.

[channelmaniac]

Those will work fine.

You should check the +5v line to make sure it's within tolerance (4.75 to 5.25) and replace any bad RAM chips that show up when the test is run multiple times.

The Apple memory tests are a first match an exit type of test. The first failure they see is what they report so you could still have bad memory chips after replacing the one that was reported as bad the first time.

RJ

[InsaneDavid]

Those will work fine.

You should check the +5v line to make sure it's within tolerance (4.75 to 5.25) and replace any bad RAM chips that show up when the test is run multiple times.

The Apple memory tests are a first match an exit type of test. The first failure they see is what they report so you could still have bad memory chips after replacing the one that was reported as bad the first time.

RJ

The parts just came today (it's nice having Jameco just up the bay, next day shipping or I can go pick up will call for big stuff). I'm going to change them all out and install sockets for them while I have everything taken apart. I'll also go over the power supply again but I checked that last week when I was doing early preventive maintenance and it checked out. There was a loose screw inside the power supply housing so I removed it to take care of that. Thanks!

[InsaneDavid]

Well crap, forget that. The underside of the board is severely oxidized over on the front right corner and along the front (under the keyboard where the RAM is located). There's a ton of rust on the bottom of the case there, more than likely from improper storage since it's right next to the vents. Most of the traces look like they're on their last leg as do a good number of components and vias. I don't want to put more time into this project, especially since I was more interested in the cards under the hood, the Unidisk drives and the software package. A bootup attempt again before preparing repairs gave a flickering garbled mess - she's done.

I do have another question, however. What IC's on the board make a IIe an "Enhanced" IIe? If anything I'll pull those if they're in good shape, most of the damage seems localized to the front of the board.

[Tupin]

A quote from Wikipedia:

The purpose of the update was to make the Apple IIe more compatible with the Apple IIc (released the previous year) and in some respects to a smaller degree, the Apple II Plus. This change involved a new processor, the CMOS based 65C02 CPU, a new character ROM for the text modes, and two new ROM firmware chips. The 65C02 added more CPU instructions, the new character ROM added 32 special "MouseText" characters (which allowed the creation of a GUI-like display in text mode, similar to IBM code page 437), and the new ROM firmware fixed problems and speed issues with 80 columns text, introduced the ability to use lowercase in Applesoft BASIC and Monitor, and contained some other smaller improvements (and fixes) in the latter two (including the return of the Mini-Assembler—which had vanished with the introduction of the II Plus firmware).

I would recommend getting a Platinum IIe if you want one that works, they were made as late as 1993.

[InsaneDavid]

I would recommend getting a Platinum IIe if you want one that works, they were made as late as 1993.

No thanks, my history is with the Enhanced IIe, this one just looks to be the victim of storage in a garage / attic / crawlspace / shed that opened it up to outside elements.