Re: Apple II Europlus memory problem?

[mjmahon@aol.com (Michael J. Mahon)]

john_junk@talk21.com asked:

>I have recently bought a non-working Apple II Europlus, and I think
>the problem is with the memory, but I would like some advice please.
>
>When powered on the machine beeps and displays:
>
>
>            APPLE ][
>
>
>]


So far, so good!

>If I press <Return> then it enters the machine monitor thus:
>
>F130 - A=C3  X=38  Y=03  P=B5  S=F2
>*

Sounds like it's having trouble reading the APPLESOFT ROMs
reliably.  Try carefully "skootching" them up a millimeter or so
in their sockets, then pressing them down again firmly.  This
cleans the contacts and frequently makes the problem go away.

Often the same result can be obtained by putting "seesawing"
finger pressure on alternate ends of the chips.  If you hear a
sound as the chip seats more firmly, that's a good thing.  ;-)

>I can view memory addresses.
>
>If I press control-c (cold boot) it goes back to the ] prompt.
>
>The memory has been expanded by a previous owner. One of the 4116
>chips (top left sitting at the keyboard) has been removed and a 16 pin
>jumper is plugged in, which connects to a memory board.

This is the "standard" 16KB RAM expansion, or "Language Card".
It can be switched into the ROM space under software control.

Since this can override ROM, you might try the machine with this
card removed.  This will require replacing a 4116 chip in the socket
that the card currently plugs into.  This chip is normally located
adjacent to the point where the 16-wire cable connects to the
RAM card.

>Can someone please explain Europlus memory to me, and how to configure
>the memory size of the machine.

AFAIK, there are no significant differences in the memory map of
the Europlus model.  Documentation for the Apple ][+ is relevant.

-michael

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