*** Cartridge Reading***
   If you want to know how to dump the hidden 512kB this is what you 
do to access it. After you set up the cart for copying, You have to set 
address lines 20 and 21 HIGH, then set the !reset HIGH and finally set 
pin 31 (the pin to the left of cart_in) LOW. Also !C_OE and !C_CE 
should be LOW. If you look at the cart with the chips facing you and 
the pins at the bottom start from the left at pin 1 you count 32 pins. 
Address 20 is pin 8, address 21 is pin 9, !reset is pin 27, and then 
you have pin 31, also !C_OE is pin 16 and !C_CE is pin17. After you set 
these pins you can double check that the 512kB chip is enabled. Put a 
logic probe on the 3rd pin down on the right side of the chip with the 
number HC74, you should get a HIGH (this is pin #5 on the HC74, it is 
a dual D type Flip-Flop [74HC74]). Now dump the cart as if it only had 
512kB. If you are using an EPROM programmer set it to read chip type 
27040.
   Some info on the chips. The two larger chips are the ROM chips, 
the one on the right is slightly larger, this is the 2MB chip. The 
other one on the left is the 512kB chip. The three small chips labeled 
AC08 74AC139 and HC74 are what enable the 512kB chip. AC08 is a quad 
AND gate [74AC08], and the 74AC139 is a Dual 2-to-4 line Decoder.

                                                   Rizzo