Re: IIe Questions!

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

David Empson <dempson@actrix.gen.nz> wrote:

> Tony Cianfaglione <ab616@chebucto.ns.ca> wrote:
> 
> > > The general type of IIe would help narrow it down: if it is a platinum
> > > one (with numeric keypad) then it is 1987 or later.  The original
> > > machine would be 1983 to 1987, and this can be narrowed down further by
> > > determining the motherboard revision (A, B or enhanced).
> > 
> > This is platinum with numeric keyboard.
> 
> I don't have one of these, so I won't be able to narrow it down more
> than "1986 or newer".

I do now!  Just picked up a platinum IIe that would have been dumped
otherwise.  It is the international version, so the motherboard layout
differs somewhat from the US one: as with the earlier international IIe
motherboard, the auxiliary slot is in the middle of the board (in line
with slot 3) and the CPU is where the auxiliary slot would be in a US
IIe (near the power supply in the lower left corner of the motherboard).

I'm interested to note that this one says "International NTSC" at the
back of the motherboard.  The older international IIe (British version)
was PAL, with a slightly different master crystal frequency.  The
crystal isn't labelled with a frequency in this one, but I assume it is
14.31818 MHz.

This machine was made in Singapore, so its serial number is unlikely to
be in a similar series to Tony's machine.  The motherboard legend at the
back says "1986/87" for the copyright date.  Several chips have 91xx
date codes, so it looks like it was made in 1991 or 92.  The latest is
9137, which would be early September 1991.

Aha!  I just spotted a stamp on the right edge of the motherboard that
says "Assembled in Singapore 9140".


On a related issue, this machine also has the "Test" position that was
mentioned elsewhere on this thread.  As described by Wayne Stewart, it
is a six-pin position with two large holes cut out of the circuit board
which look like cable guides or possibly mounting positions for some
kind of connector.  Unlike the US version, in this IIe the connector is
in the upper right corner of the motherboard, near the game connector.

Of the six pins, only two of the connections can be clearly seen from
the top of the motherboard.  Pin 2 is ground, which is connected to a
large ground plane, and has a track looping around pin 3 to the same
ground plane (beats me why, other than to improve the grounding).  Pin 3
goes to a long track that heads out into the middle of the ground plane.
I've traced this signal back and identified it as the 14M master clock
(14.31818 MHz).

The other four pins will be harder to identify, short of pulling the
machine apart.  From a little browsing, I've managed to locate the
following:

Pin 1 is SYNC*, which is the video sync output.
Pin 5 is the output of the LS166 video shift register.
Pin 6 is WINDW*, which is the output enable of the video ROM,
corresponding to the active video region.

I haven't been able to track down pin 4.

It looks like this is intended to be connected to some circuitry that
tests the video output in some way, possibly in conjunction with some
software that does particular test operations on the video circuitry.
It might just be for monitoring the video output produced by the
machine's self-test.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand