Hanimex pencil 2 double bios

[ppj34]

Hello,
 

I recently purchased a hanimex pencil 2.
Unfortunately, for this computer, information is scarce, except that it would be a colecovision with an added keyboard and a different bios (to simplify what I found on the web).

Not having the coleco adapter, I would like to install a second coleco bios on this machine, either in a single eprom (including the two pencil bios - coleco), or by adding a second eprom connected to the machine's motherboard.
A switch switch would allow you to choose the bios before turning on the computer.

Does anyone have any advice / information for me please?

[cdoty]

I did the reverse to the Colecovision..

 

To use two bioses, I just followed the instructions for a dual boot Coleco bios, but used the modified Pencil II bios as the second one. I imagine the same process would work for the Pencil II.

Edited June 28, 2021 by cdoty

[cdoty]

Looking at the board here:

It looks like you could just replace the 2764 eprom chip. Given that a 2764 can be problematic to program sometimes, I would recommend using a 27c256, or an eeprom equivilant, and duplicating the bios 4 times.

Or if you want to make a switchable version, combined the bios files and duplicate that once.

 

Edited June 28, 2021 by cdoty