Re: Problem with II2 RAM

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

<Jim.Low@logicbbs.org> wrote:

> When I got the infamous Apple IIe RAMtest error 01000000, I changed the
> second chip from the end.  It took two tries.  It's the one opposite what
> you would think from the error display.

The display shows the bits in the order in which binary values are
normally written: the most significant bit (number 7) on the left, and
the least significant bit (number 0) on the right.

On the IIe motherboard, the RAMs are the other way around, with bit 7 on
the right and bit 0 on the left.

It is debatable whether it would have been better to display the
self-test result in the same order as the RAM chips.  It would be rather
confusing on the platinum IIe, which only uses two chips (each 4 bits
wide), and it makes more sense from a software point of view.

(All you have to do is look at the computer from the back, and they are
around the right way.)  :-)
-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand