Re: Unitron EPROM Writer UPDATE

["Tim Haynes" <trhaynes@yahoo.SPAMBGONE.com>]

Hi Mark!

Thanks for the pin numbering descriptions - this should help me quite a bit!
I will try to answer your quesions below.

"Mark Cummings" <NOTfigjams@primus.com.au> wrote in message
3bd2c91c@news.iprimus.com.au">news:3bd2c91c@news.iprimus.com.au...
> Tim,
>
> I have been working on those scans to draw out some kind of circuit
drawing.
> While the back is pretty easy to follow, I'm afraid it's impossible to
> follow the tracks on the component side without actually having the board
in
> hand.
>
> Unfortunately while that close up scan does make it easier to read the
IC's,
> it's still pretty hopeless trying to see where those tracks go in the
> shadows or under chips.
>
> So far I don't have enough of the circuit to come to any conclusion, but
if
> you can trace (follow) some of the tracks on the component side that may
> help. I assume you know how the chips pins are numbered. If you can remove
> the chips temporarily that may help, just keep a note of where they go and
> which way. Also that ZIF might get in the way, my AP-64e EPROM programmer
> has a socketed ZIF so I can pull it out, the Unitron one appears to be
> soldered onto the board.
>
> this is what I need to fill in some of the gaps:
> where do the following tracks go to (if they exist) on each of the
following
> ?
> (BTW if the track goes to a passive component, like a resistor or
capacitor,
> forget that and keep following it to a chip leg if applicable). Some may
go
> to a few places.
>
> 1. Socket 08 pin 1, 5, 6 & 12
pin 1 - socket 16, pin 1 (but kind of hard to tell - a flashlight shining
through the board seems to indicate that this is right, though)
pin 5 - super hard to tell (wish my multimeter wasn't broken!).  I believe
this goes to Socket 16 pin between pins 9 and 10 and perhaps onward further.
Very tough call.
pin 6 - seems to go to Socket 16 pin 9
pin 12 - this has two connections on it.  One is connected to Socket 08, pin
8 (believe it or not).  The second one goes along the back and disappears
under a bridge across the bottom of 6821 and resurfaces on the component
side, continuing on to a point between the legs of the yellow capacitor(?)
immediately between the 6821 and the 2716.  From there, it goes under to the
solder side again and continues on to an edge connector.  It is connector 9
counting from the end of the card (the end with the toggle switch on it, not
the end with the ZIF socket on it).

> 2. Socket 16 pin 3, 11 & 12
pin 3 - between pins 11 and 12 on socket 32 and possibly on further (oh for
a working multimeter!!)
pin 11 - 6821 pin 13 (wow)
pin 12 - 4040 pin 15

> 3. Socket 32 pin 2 & 3
pin 2 - almost impossible to tell.  I really need to get a new multimeter!
pin 3 - same story.

> 4. Socket 64 pin 1, 3 & 6
pin 1 - I would guess pin 13 of socket 32 - again, I need a good multimeter
to know for sure
pin 3 - almost impossible to tell.
pin 6 - I would guess pin 3 of socket 32.

> 5. ZIF Socket pin 2, 26, 27 & 28
pin 2 - whew - tough one.  It gets all mixed up in the header sockets.
pin 26 - pin 7 of 6821
pin 27 - pin 6 of 6821
pin 28 - pin 5 of 6821

> 6. 7406 pin 1, 3 & 7
pin 1 - appears to be disconnected from everything
pin 3 - same as pin 1
pin 7 - tough one - it seems to be connected to the large mass of tracing
covering the solder side of the board above the edge contacts.  Do you need
me to indicate all of the things that are connected to that tracing mass?

>
> Although I can't see these can you confirm the following:
>
> (A9) ZIF pin 24 - 4040 pin 14
This seems to go to pin 9 of 6821 on the solder side.  On the component
side, I would say pin 8 of 4040.

> (A8) ZIF pin 25 - 4040 pin 12
Pin 8 of 6821 on the solder side, on the component side, this doesn't seem
to go anywhere.

> (A7) ZIF pin 3 - 4040 pin 13
Hmmm... I don't think so, but I also can't tell where it is going!  The
trace seems to be sandwiched in the silicon.  Did I mention that I need a
new multimeter?

> (A6) ZIF pin 4 - 4040 pin 4
> (A5) ZIF pin 5 - 4040 pin 2
> (A4) ZIF pin 6 - 4040 pin 3
> (A3) ZIF pin 7 - 4040 pin 5
> (A2) ZIF pin 8 - 4040 pin 6
> (A1) ZIF pin 9 - 4040 pin 7
> (A0) ZIF pin 10 - 4040 pin 9

Are you numbering these ZIF pins the way you mentioned in your other post?
It sounds like your pin1 is beneath the "L" of "texttool", but I think you
described pin 1 as being near the lever.  Please verify the number, and I'll
confirm these other ZIF pins.

>
> I'm still working on the theory that the header will be wired as:
> 1-14
> 2-13
> 3-12
> 4-11
> 5-10
> 6-9
> 7-8 (although I'm not sure if this last connection is used)

Hmmm... not really sure what you mean by those pairs of numbers.  Is the
header a single chip or a group of 4 (I would think 4 - one for socket 08,
one for 16, one for 32, and one for 64.  Am I totally off?)

> The chips you need were:
> 7406 - quad NAND gate Open Collector (don't use any other type or the
smoke
> will get out)

Heh - I actually have another board with one of these that I can scavenge.

> 74LS74 - dual D Flip Flop +ve edge triggered.

I don't think I have one of these, but I can get one.

> I am not sure why +12V is supplied from the Apples bus pin 25, unless the
> programmer also programs 12V EPROMs. Most older EPROMs were 21-24V. This
> might complicate the issue, although I'm hoping if you can supply some or
> all of the above answers it might become clear.

I hope my descriptions have been some help!!

> BTW: Congratulations on getting the GS networked to your Win2K PC, I bet
> that has taken your fun to new heights, and this little EPROM project will
> probably take a back seat for a bit.

Not at all!  Well, the backseating of the EPROM project has been due to the
upcoming halloween party that my wife and I are throwing.  It's going to be
80's themed - a perfect environment for showcasing my Apple II stuff!!!! :)

Cheers!!
Tim