Hi,
I need a help for my apple IIe, starting the self-diagnostic test I obtain on my monitor the following string:
RAM: F13 F12 F11 F10 F9 F8 F7 F6
Or sometimes
RAM:
I have changed the following ICs:
SN74LS125N
74S109
SN74S10N
and ONE 4264 (DRAM)
I have also cleaned the pins of the ROMs and MMU
But the problem still remain.
Note that I'm able to write basic instructions and the apple IIe run them, but none of my software on floppy works:
-UNABLE TO LOAD PRODOS
-sometimes I obtain
A1DD- A=28 X=FA Y=40 P=38 S=E6
*
Please can you help me,
Alex
Based on what you describe, the computer CPU seems fine. It seems like your disk or drives or both might be the problem. Do the head cleaning, drive speed adjustments (both procedures have been previously described in this section of the forums), and use a good known disk to test the drives. Or try a drive and disk that are known to be already working.
Mutant Pie
I tried with 3 different drives,2 controllers and about 20 floppy disk.
I've obtained the same results,i've changed all the electrolytic capacitors too.
What led you to diagnose the problem as that one DRAM in particular?
Try running a memory test: http://www.willegal.net/appleii/6502mem.htm
It'll tell you what addresses are failing, and what the expected versus actual result was (so you can see what bit, and therefore what chip, is failing.)
I thought that if really was a ram problem, changing one of the chips, the message would have to change.
(not all the ram chips should be displayed at the end of the test)
Now I'm going to follow your link. tx. I will report the results asap.
The DRAMs are one bit wide.
So, you can have a failure at a certain address, and the bit within the byte that is wrong points to the chip that has failed.
But...
What exactly means the message "RAM: F13 F12 F11 F10 F9 F8 F7 F6" ?
That all the RAM chips doesn't works?
If the answer is "YES", changing one chip the message MUST change...
If the answer is "NO", it's a nightmare... this means that the TEST it's a fake.
Hello,
According to Apple website, there is no doubt about what the message means.
But I agree with you : if you change one RAM chip, one error should go.
So it seems more complicated than it is. There is obviously another problem.
The RAM is tested at the end of the diag so apparently all the other chips are good.
Are the chips into sockets ? If so and if you have another known good Apple //e, I suggest a MMU/IOU swap.
Ok, so may be the RAM has no problems (but we are not really sure)
Obviously I have already removed and reinserted all the chips into they sockets.
The RAM chips are soldered directly on the motherboard, so for testing the RAM, I replaced one of them using a new socket.
But we must go forward.
I have bought one IOU from ArcadeComponents.com, but not exactly the same because seems impossible to find: in my Apple IIe there is a 344-0022-A, but I have bought a 344-0021 (they told me this is an international version of the chip)
After changing the IOU chip the computer is not able to start the Self Diagnostic Test.
Trying to start the Diag pressing the keys or leaving the keyboard disconnected result in a blank screen or sometimes displays a random number like C431* or C423*.
Unfortunally I'm not able to find another Apple IIe for other tests.
If someone has other ideas or tests to suggest me, I tell you that I have also a 4 tracks oscilloscope and a signal generator. Thank you in advance
Alex:
Try changing the RAM I have had many of these go bad. It could be one of the Chips on the RAM has gone bad not unusual for them to go bad.
Hello Alex,
There is a lot of confusion about the IOU.
Check out Tezza's article. The dead link "this other site" was pointing to this article :
BTW, with an oscilloscope, you should be able to track down the problem using the Apple //e SAMS book as a guide.