Well i tried it out today on Big House 713. Awesome Sauce!! FREE PLAY DAYS!!
I modified the txt file for myself and for others to read but just replace Prom1 and set coinage switches off.
BUT i hate when note files are pretty blank.
Patches SYSTEM 80B
Make sure you choose the correct version of PROM corresponding to your Pinball,
then unzip the archive downloaded. Only the PROM1 is changed and the extracted
file must be programmed in memory, EPROM 2764, or a 2864 EEPROM.
Replace this PROM1 memory on the Piggyback by this new version
How does it work ?
For switch to FREEPLAY mode, you should position the full set of the DIP switches
for coin's configuration to the OFF position
(1-4, 5-8, 9-12 on SYSTEM 80 or 1-5, 9-13, 17-21 on SYSTEM 80A and 80B).
This corresponds to a configuration that is usually never used (and that is easy to remember).
Since then, the credits will be automatically recharged when they fall to zero.
It is the only thing that changes.
To disable the FREEPLAY, simply set back the DIP switches to their original position.
Tested and verified working on Wednesday Oct 28, 2015 by CNKay.
Original Big House 713 Prom1 rom check sum 0E08.
The home version BH713 Prom1 rom check sum 03DB.