MROM64C board page

PCB build instructions

1. Solder all top-side chips (U2, U3, U4) and capacitors (C2, C3, C4).
2. Solder the capacitor (C1) and pull-up resistors (R1 - R7) on the underside.
3. Break apart some single-row round pin headers. One length of 3 pins and two lengths of 14 pins are needed.
4. TBC

Programming instructions

First, prepare an image to program to the "010" chip.
The easiest way is as follows:

1. create a desktop folder named "characters" and copy 16 character ROMs into it.
2. create a desktop folder named "kernals" and copy 1 BASIC ROM and 7 kernal ROMs into it.
3. create a desktop folder named "combined" and leave it empty.
   You should now have a folder structure like this:

   .
   |--characters
   |   |-- character0.bin
   |   |-- character1.bin
   |   |-- character2.bin
   |   |-- character3.bin
   |   |-- character4.bin
   |   |-- character5.bin
   |   |-- character6.bin
   |   |-- character7.bin
   |   |-- character8.bin
   |   |-- character9.bin
   |   |-- character10.bin
   |   |-- character11.bin
   |   |-- character12.bin
   |   |-- character13.bin
   |   |-- character14.bin
   |   `-- character15.bin
   |--kernals
   |   |-- basic.bin
   |   |-- kernal0.bin
   |   |-- kernal1.bin
   |   |-- kernal2.bin
   |   |-- kernal3.bin
   |   |-- kernal4.bin
   |   |-- kernal5.bin
   |   `-- kernal6.bin
   `--combined
   
   

4. Navigate to "characters".
   If using windows, open command prompt in this folder, and execute:

   copy /b * combined_fonts.bin

   If using linux, open a terminal in this folder, and execute:

   cat * > combined_chars.bin

   Copy combined_chars.bin into the "combined" folder.


5. Navigate to "kernals". If using windows, open command prompt here, and execute:

   copy /b basic + kernal0 + kernal1 + kernal2 + kernal3 + kernal4 + kernal5 + kernal6 combined_kernals.bin

   
   If using linux, open a terminal here, and execute:

   cat basic + kernal0 + kernal1 + kernal2 + kernal3 + kernal4 + kernal5 + kernal6 > combined_kernals.bin

   Make sure to substitute correct file names.
   Copy combined_kernals.bin into the "combined" folder.


6. Navigate to "combined", which should now look like:

   combined
   |-- combined_char.bin
   `-- combined_kernals.bin
   

   Combine these two files using

   copy /b combined_char.bin + combined_kernals.bin mrom64c.bin

   or

   cat combined_char.bin combined_kernals.bin > mrom64c.bin

   as appropriate, making sure that the character sets are first.

Memory map

Setting a kernal and character ROM

Kernal and character ROM banks are binary-numbered. On the board is a pin header with a series of pins labelled F0 to F3 and K0 to K2. Open pins are high by default due to pull-up resistors. To set a low state, close a a pin pair with a jumper or otherwise.

Attention!

K0, K1, and K2 simultaneously low is an illegal combination and the C64 will not boot. Do not close all three headers or set all three low together.

Page created: 18DEC2025
Last modified: 18DEC2025