Re: Apple Ram Card

[dempson@actrix.gen.nz (David Empson)]

In article <2pgihb$10n@senator-bedfellow.mit.edu>,
Paul H Bauer <pbauer@ATHENA.MIT.EDU> wrote:
> 	I recently aquired an Apple Ram card which I would like to use.
> This is the card that will go in slots 0 thru 7, not the aux slot.

Is this a genuine Apple card, i.e. the "Apple II Memory Expansion
Card"?  It should have an Apple logo on it somewhere.  Here is a rough
picture of the card, with 256k installed:

-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX      Custom IC
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX      over here
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX

-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX       ROM 
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX     down here
-- -- -- XX -- -- -- XX -- -- -- XX -- -- -- XX

                                            Slot connection here


Note: I don't actually have one of these cards - I just have the
technical reference manual.

> The problem is that when I install the card the system will load
> prodos and then freeze, as though it is trying to read from a
> nonexistant place.

It sounds like the card is faulty.  Maybe one of the RAM chips is
damaged.  Try running the card's self test, as follows:

1. Start up the computer without a disk in the drive, and press
Control-Reset to get into BASIC.

2. Type CALL -151 and press return.  This will put you into the system
monitor, with an * prompt.

3. Type Cn0AG (replace 'n' with the slot number, e.g. C40AG if the card
is in slot 4) and press return.

The test will run continuously until you press ESC.  It takes about 45
seconds to test 256k.

It prints out text messages indicating the progress of the test.  If
there is a problem with one of the RAM chips, you will get a message
like this:

CARD FAILED
DATA ERROR nnnnnn - nn
SEE DEALER FOR SERVICE

The 'nnnnnn' is the address at which the card failed, and the 'nn' is
some indication of the failed data.  In theory you can take this
information to your Apple dealer.  In practise, E-Mail me (or post it)
and we should be able to work out which chip is faulty.  The technical
reference manual includes a source listing of the card's firmware
(including the self test routine), so I should be able to decipher the
error message.

If the card hangs when you try to use the self-test, there may be a
more serious problem.  E-mail me and I'll see if I can help further.

> At present there are only 256k of memory on the card. I would also
> like the layout of the memory on this card. 

If you want to add more RAM chips, you need to add them in multiples
of 256k (eight chips at a time), using the sockets to the left of the
existing RAM.  The chips should be the same type as the existing ones
(41256, I think).

Perhaps you meant the _internal_ memory organisation of the card.

Slot-based RAM cards of this type are nick-named "Slinky" cards.  They
have a single byte I/O location to access RAM on the card, and a
three-byte address register.  Whenever you read or write a byte, the
address is automatically incremented (so the address "slinks" through
memory on the card).

The card is normally used as a RAM disk, but can also be used as
"off-load" memory expansion by some programs (e.g. AppleWorks).  You
cannot execute code directly from the card, only use it as storage.

The recommended way to access the card's RAM directly is by using
SmartPort calls.  This is all documented in the manual mentioned below.

The card automatically acts as a RAM disk for ProDOS and for Pascal
1.3.  It can also be used with DOS 3.3 (type IN#n after booting DOS to
initialize the card firmware and connect the RAM disk support to DOS).
The INIT command is disabled when you do this.

> 	Does anyone have any documentation for this card?

You can get the "Apple II Memory Expansion Card Technical Reference
Manual" from Resource Central, for US$15.  Their product code is
DA-009.

E-Mail me if you want more information.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand