Here are some random notes on the expansion options for the
89410A/89441A, for the sake of the archives.

Second Channel
--------------

It's possible to add the second input channel option in the field. An
input channel (either one) consists of a pair of boards, A10 and A21.
The board pairs are identical between channel one and channel two. It's
possible to take a channel one board set from one 89410A/89441A and add
it as a channel two board set in another unit. The firmware will
recalibrate the ADC on the first power-up with the new board set
installed, which takes several minutes.

The only configuration change required to use the second input channel
is a jumper on the A35 source board. Several of the self-tests and the
calibration routine will fail unless you move this jumper. It's a
wider-than-usual black plastic jumper near the connector along one edge.
There are two positions; one position is for a single-channel system
and the other is for a two-channel system. If you add a second channel
and forget to move this jumper, and see the self-test failures, just
power down, extract the A35 module, move the jumper, and start it up
again. It will now work, assuming the added board set is functional.

Memory
------

Options UFG and UTH are nearly identical; both options add more I/O
(an Ethernet port, for one) and additional RAM and take the form of the
topmost board in the backplane that's accessible from the rear of the
instrument. How they differ is in the amount of RAM that they provide;
UFG adds 4MB, while UTH adds 20MB. There's 4MB on the option board, and
a 72-pin SIMM socket that's either empty in the case of option UFG, or
populated with a 16MB SIMM in the case of option UTH.

One can remove an option UFG board and install an option UTH board,
and the system will see it with no configuration changes required. One
can also add a 16MB SIMM to an option UFG board and turn it into an
option UTH board; no configuration changes are required on either the
board or on the system.

It's possible that there's an earlier revision of the option UFG board
that lacks the SIMM socket, but I've not confirmed this.

I've not yet determined what type of SIMMs these boards use, though
they look pretty ordinary. I've also not yet determined if it will take
larger SIMMs.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA