[sdiy] Eventide H949 obscurity - IEEE 488 interface

[Magnus Danielson]

Dear all,

As a friend came over with his H949 I got a reason to pop my H949 out of the
rack and look at it. Both needs attention, so why not double the joy! ;O)

Anyway, both the boxes themselfs and the manual seriously hints about their
being an IEEE 488 remote control option. There is also some unmounted
components on the main board (bottom) hinting about this (doesn't BUS ADDR
written in the top-layer next to an unmounted component give the GPIB-vibes to
you?).

Looking in the H949 Instruction Manual from Mars 1979 there is a number of
mentioning of the IEEE 488 remote control functionality.

I know that the IEEE 488 remote control operation can do this:

* Select Manual (for Control Mode) - indicated with GREEN LED next to button
* Select Keyboard (for Control Mode) - indicated with GREED LED next to button
* Select CV+Man (for Control Mode) - indicated with GREEN LED next to button
* Select Remote (for Control Mode) - indicated with GREEN LED next to all
  control mode buttons
* Provide a pitch ration

I've almost completed the reverse-engineering of the IEEE-488 curcuit itself.
It is pretty self-contained down there on the bottom board, using GND and +5V
and then being a bunch of chips, a DIP-switch, a resistor-line, a resistor and
a cap between two 16-pin contacts. One end is the IEEE-488 and one end is a
8-bit bus with handshake.

I've also reverse-engineered the other chips which is not mounted on the bottom
board. That part of the design is not completed, a few wires is missing for it
to make sense.

There is yeat more evidence like an unused connector on the front-board which
fits nicely in with the capability of controling the LEDs above (you can't see
it on the schematics).

Also, when you look at the top board there is a number of connectors which has
a lot of usefull signals pulled to it.

A pair of the connectors on the top-board is to be used for the Alg-3 board.
I've got that one, so I know.

However, there ought to be a fifth board to make it all fit together. There is
screw-holes on the top-board and on the Alg-3 board which only makes sense for
a fifth board. I would assume that this board adds PROMs for the ALU, data
paths necessary and additional glue-logic.

Additionally I might add that there is also good evidence of a planned memory
expansion. You need an additional 11 4116 rams, a 74LS00 and cut a wire for the
actuall memory extention. I would assume a change of PROMs for it to make
sense too. Oh, you need to punch an additional hole in the front in order to
let the added delay-button (for which there is PCB-layout on the front-board
and which is expected to be pulled over to D14 on the D4 connector, possibly
through a driver - haven't checked that detail just yeat).

Anyways, I've found some new things out and also been able to articulate my
questions a little better. What is known about this fifth board? Did it ever
go into production? Anyone got one? (MUST ask this one) Schematics and PROM
files? ;O)

I know that this thing was designed by Anthony Agnello and that he is supposed
to be back at Eventide.

Cheers,
Magnus - diging in analog/digital sound-effects showing age