Hi,i'am Federico from Italy (sorry for my bad english).
i am a retro-lover, mostly Commodore stuffs, but i have some other cool
stuffs too (Zx Spectrums, Acorn computer etc.).
Recently i picked up an Apple IIe at a very very good price and, even if i
never owned one, well ... this is history, so i got it!! (and i am very
happy!!!)
is a 1983 Apple IIe, European version, with a SSC, a DuoDisk and a 80Column
card.
not easy for me understand something, because i have zero experience on
Apple IIe, but after a lot (lot lot lot) of on-line reading, i've made
some progress ...
The Apple IIe start up, give the "beep", give the Apple ][ on top of screen.
if i press "Control+Reset" go on prompt.
On prompt i can type classic Basic programs (for i = 1 to ... print, goto
etc.).
work perfectly, zero problems.
i can go on 80 Colums (command PR#3, found on line), no problems, work.
Duo Disk spin at start, but i have no disks to test so i gone on line
searching how to transfer some software.
found ADTPro and decided to try the "Audio way" because seem to me more easy
than use Super Serial Card (changing switches etc.)
every thing seem work perfectly, i can transfer on RAM the bootstrap (if
i've well understand) ... but when i try to make it run on Apple IIe, i got
for 1 second the screen of ADTPro and then an error about "Allocating ram
error", something similar.
searching on line lead me to think is a ram problem.
more on-line research, and i discovered that AppleIIe have an internal ROM
Diagnostic test, pressing a combination of solid and empty Apple.
tryed it
the result is:
ram: f13 f12 f11 f10 f9 f8 f7 f6
or, sometimes, only
ram:
and the system hang on.
system not even start doing nothing, just instantly go on this error message.
i've read the system should test ROMS, BASIC etc, at the end ram, but, as i wrote, instantly go on the message above.
i've try same test even without any card, nothing changed.
after that, searching on this board for help, i've try other things:
-) type HDR for go Hi-Res and , even if work, i've see that there are 3 "i" around the screen, that should indicate some ram problems
-) type "C050 C053 C054 C057 N 265:FF N 266<265.BFFEM 266<265.BFFEV 265:0 N 266<265.BFFEM 266<265.BFFEV 34:14" after going on monitor mode (CALL-151) and this give me errors. On this board i've read that if i have errors, mean rams are fault
everything seem to lead me on ram problems, but is possible every chip is fault?
and, why
on line i see that diagnostic test, if there is a ram problem, give something like:
0 0 0 0 0 1 0 0
indicating witch chip is fault, while
my test don t do like this, but instantly go on RAM: or RAM: f13 f12 f11 f10 f9 f8 f7 f6
... so i have NO IDEA wich chip can be bad?
last, i've recovered 8 ram chips for Apple IIe, i've try piggyback (all rams are soldered) and nothing changed, always the same problems.
i'am looking for help, believe me, i've read a lot and searched a lot and i've found another topic around with my same problem, on 2011. But was not solved, just a dead topic.
thank u a lot and bye
Federico
;(
no one can help me?
no one have never seen this message on diagnostic test?
I don't know which geek recomended in a former thread that
soldering IC's piggyback might help....
BUT: THIS IS BAD RECOMMENDATION !
Only clean desoldering and replacement with clean soldering is
professional and reliable solution ! Soldering a working IC
piggyback on a damaged IC might even damage the working good IC !
Most IC's of that period of time had a limited fanout and might
get damaged by a piggyback solution.
speedyG
+1 on Speedy's post. The only way to correct a damaged or non-functional IC is to replace it.
I would never piggyback a good part over a bad part.
If you go to the effort of desoldering any ICs, solder in a socket incase you have to replace that IC again.
wm
BUT:
bear in mind - that test might instead indicate dsmsge of traceline or bufferchip !
If it displays single chip it might indicate trouble with dataline ( Bit )
and display of entire line might indicate adressingline or bufferchip (i.e.A7 or similar )
Remember also:
Testdisk for ][ or II+ ... it does not check MMUchip....
this is only performed by //e-Testdisk !
speedyG
[quote=speedyG]
sorry, i am little noob, so, what u think i should try/check?
witch IC i should check for troubleshooting?
and ... thank you for any help
The term A7 ist the "abbreviation" of adressingline #7.But the CPU uses 16 lines to access
a specific cell in RAMand A7 was just an example .... it can be anyone of the 16 lines from A0 to A15.
There is one bufferrs block consisting of 3 ICs - at the CPU side close to it
The abbreviation is used within the circuitplan.of the Computer.
Befor making further attemps of repair it is urgently recommended for noobs to learn more
about the hardware and functions within the Apple II !
Otherwise attempts might cause more damage than repair.
There are 3 basic sources for information and knowledge:
the circuitplan itself:
Sams ComputerFacts - Apple II, II Plus.pdf
and 2 books with detailed explenations:
W. Gayler - The Apple II Circuit Description.pdf
( focused more to technical details )
and:
Jim Sather - Understanding the Apple II.pdf
( more general function )
and with good tips to narrow down problems and detecting damaged chips:
Chilton - How To repair and maintain your Apple Computer.pdf
it has been previously urgently recommended several times to download the books and save them for future access and rereading.
when downloading be aware that this files are really large ( up to aprox. 100 MB )
ane therefor require quite some time for downloading.....
sincerely
speedyG