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Thread: Apple II Computer

  1. #1
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    Default Apple II Computer

    My latest edition to the family is a

    Apple II Europlus computer

    some details

    Apple II Plus
    The Apple II Plus, introduced in June 1979,included the Applesoft BASIC programming language in ROM. This Microsoft-authored dialect of BASIC, which was previously available as an upgrade, supported floating-point arithmetic, and became the standard BASIC dialect on the Apple II series (though it ran at a noticeably slower speed than Steve Wozniak's Integer BASIC).
    Except for improved graphics and disk-booting support in the ROM, and the removal of the 2k 6502 assembler/disassembler to make room for the floating point BASIC, the II+ was otherwise identical to the original II. RAM prices fell during 1980–81 and all II+ machines came from the factory with a full 48k of memory already installed. The language card in Slot 0 added another 16k, but it had to be bank switched since the remaining CPU address space was occupied by the ROMs and I/O area. For this reason, the extra RAM in the language card was bank-switched over the machine's built-in ROM, allowing code loaded into the additional memory to be used as if it actually were ROM. Users could thus load Integer BASIC into the language card from disk and switch between the Integer and Applesoft dialects of BASIC with DOS 3.3's INT and FP commands just as if they had the BASIC ROM expansion card. The language card was also required to use the UCSD Pascal and FORTRAN 77 compilers, which were released by Apple at about the same time.

    Apple II Europlus:

    After the success of the first Apple II in the United States, Apple expanded its market to include Europe, Australia and the Far East in 1978, with the Apple II Europlus (Europe, Australia) and the Apple II J-Plus (Japan). In these models, Apple made the necessary hardware, software and firmware changes in order to comply to standards outside of the U.S. The power supply was modified to accept the local voltage, and in the European and Australian model the video output signal was changed from color NTSC to monochrome PAL – an extra video card was needed for color PAL graphics, since the simple tricks Wozniak had used to generate a pseudo-NTSC signal with minimal hardware did not carry over to the more complex PAL system. Production of the Europlus ended in 1983.

    My Apple II comes from an Electrontics engineer, who in the 70s and 80s designed computer circuits and plug in cards for various machines. This Apple comes from a stock of Apples he has or his daughter has as the gentleman is losing his sight.

    Anyway the Apple comes with only a disk controller and a pair of 5.25inck disks.

    i cannot test them yet and the Apple has a smelly PSU and the graphic out put is garbage as seen in the pic.

    Possible faults? Eprom or rom error?

    mike.
    Attached Thumbnails Attached Thumbnails apple mobo.jpg   IMG_2137.JPG   IMG_2138.jpg   IMG_2140.JPG  
    Last edited by mjnurney; 4th August 2012 at 07:10.

  2. #2
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    Default

    Start checking the voltage from the PSU, mate.

    After been sure the PSU is OK you can start checking the RAM chips for abnormal heat, which is a clear indication fault.

    But from the screen picture I'm sure the fault is on the video area.
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    i'll get the psu inputs tomorrow and check it , the PSU obviously has an issue as it smells the electronic smell of death but works for the moment...

    yes it does look a graphic fault ....wonder if the rom going bad does this?

    i know nothing of Apple II's

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    Back "in the day" I was strictly an S-100 guy and did a lot of work with 8080 and Z80 based systems. I always liked the Apple II though I never got a chance to own one.

    I remember prior to buying my C64 I had picked up a book on 6502 assembly language and I marveled at the small amount of instructions and registers the processor had and how much easier it seemed programming one would be.

    I was very jealous of my few Apple II friends until I bought my C64.

    Nice machine there, I hope you sort out the issues!
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    Some tips from an Apple forum

    hello mjnurmey,
    there are several causes possible that result with bad interaction of RAM with CPU:
    bad busdriverchip ( those chips in the same line like CPU ),
    bad timing ( chips in the line from oscillator to lineadressing decoders ),
    noise on powersources ( bad capacitors that don´t filter the noise away from the power ),
    and of course bad RAM-chips themselves....
    not to talk about bad interfacecard blocking the adressinglines....
    my advice:
    start first tests without any interfacecard and only one row of RAMchips.....
    this should lead up to a prompt - if the chips are O.K. and the lower adresslines are O.K.
    ( otherwise there is a problem with eiter the datalines or with a RAMchip in the first line )
    then expand by inserting second line of RAMchips.... it should end up again with a prompt.....
    next step would be to add the third line of RAMchips ( don´t forget to move down the one from the language card
    and make mark to remember orientation of that chip on the card !)
    thereafter you may put back the one chip to the language card and add the language card.
    then the next step would be to add the floppydisk contoller with one drive connected....
    if somewhere in between the problem raises again, the problam can be located within the chips swapped in back...

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    Some useful stuff on the PSU here

    http://www.applefritter.com/node/24037
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    opened up the PSU this afternoon and the following look very ill

    Astec power supply AA 11040c
    230vac 50mhz 0.5a

    C23 capacitor 0,01uf (a) X
    C1 capacitor 0,1uf (a) x

    capacitors here look very old too and i'll change them..

    c11 0,22uf +-10%
    c17 0,022uf M
    c10 0,22uf +-10%

    C23 has exploded in half and smells like a burnt fire type smell

    can anyone guide me on the voltage of these ? i haven't taken the pcb out yet to see if its on the 230v line.

    mike

    astec pin out

    1 common
    2 common
    3 +5v 2.5a
    4 +12v 1.5a
    5 -12v 0.25a
    6 -5v 0.25a
    Attached Thumbnails Attached Thumbnails film cap.jpg   IMG_2147.jpg   astec.jpg   psu.JPG  
    Last edited by mjnurney; 27th July 2012 at 19:00.

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    http://www.youtube.com/watch?v=Fu3iD...e_gdata_player

    recapped the PSU today after a visit to maplins....£2.55 for 10 foil caps (5 spare)

    still the same black pic with white blocks in the centre , more investigation needed...

    mike.

    Update:

    CPU removed from Commodore PET and tried in the Apple, this give a white ish scrambled screen but putting the original cpu back in keeps the same screen not the ------ screen as before?

    The Commodore PET cpu function perfectly in my BBC computer..

    odd.

    Another update:

    changing the RAM around gets me back to the messy single line of graphics ... so back to where i was before. it seems i have 200ns and 300ns ram in here and they can't be mixed.
    Attached Thumbnails Attached Thumbnails IMG_2154.JPG   IMG_2153.JPG   IMG_2158.JPG   IMG_2163.jpg  
    Last edited by mjnurney; 28th July 2012 at 19:06.

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    Well we had a power cut last night as the Apple II was on and then the power came back on ...now the Apple II doesn't , blank screen that flickers when power is applied...



    bad to worse....

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    Have you tested the various voltages after the new caps have been fitted??
    4 x 48K ZX Spectrums | 3 x ZX81's | 3 x A500+ | 2 x A500 v1.3 | Acorn A3010 | Amstrad ALT-286 16MHz 170Mb HD | Twinhead 486SX 25 MHz 4Mb Laptop (Dos6.22 Win3.11) | Raspberry Poo running OpenELEC XBMC | Arduinos running water harvester and hot tub

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