Re: Unitron EPROM Writer UPDATE

[Stephen Shaw <xstephenx@apple2.org.za>]

The "coding" chip for the 2716/2732/2764 sockets is a DIP switch. Leave all
switches on. I don't know if it is a 14 or a 16 pin DIP. Can't remember :-)

On Thu, 25 Oct 2001 03:14:14 GMT, Tim Haynes wrote:

> Hi Mark,
>
> I just sat down with the Unitron to help answer some questions, and have
> immediately hit a wall.  Although I took a digital design course back in
> university, little of it stayed with me!  I'm left not being able to figure
> out how the pins are numbered.  If you could briefly explain it, I will
> continue the study of this board.
>
> Thanks!
> Tim
>
> "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
>> 2. Socket 16 pin 3, 11 & 12
>> 3. Socket 32 pin 2 & 3
>> 4. Socket 64 pin 1, 3 & 6
>> 5. ZIF Socket pin 2, 26, 27 & 28
>> 6. 7406 pin 1, 3 & 7
>>
>> Although I can't see these can you confirm the following:
>>
>> (A9) ZIF pin 24 - 4040 pin 14
>> (A8) ZIF pin 25 - 4040 pin 12
>> (A7) ZIF pin 3 - 4040 pin 13
>> (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
>>
>> 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)
>>
>> The chips you need were:
>> 7406 - quad NAND gate Open Collector (don't use any other type or the
> smoke
>> will get out)
>> 74LS74 - dual D Flip Flop +ve edge triggered.
>>
>> 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.
>>
>> 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.
>>
>> Mark
>>
>>
>>

-- 
Direct from the Ministry of Silly Walks