Re: Upgrading an Apple //c

[voss@i40s16.ira.uka.de (Stefan Voss)]

In article <1994Feb23.004219.19074@csc.canberra.edu.au>, u901841@student.canberra.edu.au (Hickey / Michael Gerard (ISE)) writes:
|> Hi guys,
|> 
|> [stuff deleted]
|> 
|> He bought an Alltech ROM chip marked 344 - 0033 which I used to replace
|> the original Monitor ROM (marked MON). However, when I powered up the
|> computer all we could get was a strange checkerboard display (definitely
|> NOT the self test) which seemed to indicate that I had done ... 
|>                     (suitable dramatic music here)
|> 
|> 		    	    A BAD THING.
|> 
|> [stuff deleted]
|> What gives? I thought that the original //c had the right circuitry to
|> drive a Unidisk 3.5 but all it needed was a ROM UG!
|> 
|> Any ideas? I'm stumped.

In addition to ROM change you have to to some soldering.
On the motherboard near the ROM socket there are two soldered points 
("soldered points" may not be the correct word. In German: "Loetpunkte").
labelled "A" and "B". One looks like

  __|\_/|__
    |/ \|
      ^
      |
      |
   cut connection here

Two triangles with connected peaks. You have to *cut* the connection between
the two triangles.
The other point looks like

  __/| |\__
    \| |/
      ^
      |
      |
   make connection here

Two triangles (not connected) facing each other with their hypotenuses.
You have to *make* the connection between the triangles.

Try to find somebody who has some experience with soldering. I had problems 
when I tried to cut the connection at the first point.
I take no responsibility for this method. All I can say is that it worked
for my //c.

|>      __  |\       Michael Hickey
|>     /  |_| \
|>   ^'        \     u901841@student.canberra.edu.au

Regards,

Stefan Voss
(voss@ira.uka.de)