The MC68705R3 is one model of a family of microcontrollers from Motorola. It has 3776 bytes of EPROM and 112 bytes of RAM.
I was able to electronically dump the EPROM using non-user mode. I used a 1 MHz clock on the EXTAL pin with XTAL grounded, tied /RESET, /INT and TIMER high, and connected PC7 to 7.5V via a 1K resistor. I tied the PORT A pins to +5 and ground using 8 1K resistors to set it to $9D, the opcode for NOP. The entire 4K address space contents were output on PORT B, including the I/O ports, RAM, EPROM and bootstrap ROM; I captured the bytes using a logic analyzer.
In NUM, the chip outputs address information, fetches an opcode from memory as normal, outputs that opcode, then executes the opcode input on port A. Since the resistors feed it NOPs, it just keeps fetching the next byte and outputting it, dumping all of memory. The address info that's output is a permutation of 8 of the address bits.The dump starts at offset $D9D because when the chip fetches the reset vector, the resistors feed it $9D9D.
Here's a Logic capture of a 68705R3 dump There are 8 clocks per byte; 2 clocks of data from ROM, 2 clocks of address info, 2 clocks of the ROM data again and 2 clocks of the address info again. The entire 4K is dumped in 4096 x 8 / 1,000,000 seconds (32.768 ms).
The ST EF6805U3 can be dumped the same way.