There are 4 slots on the cartridge. These can be equipped with EPROMs, and of course also EEPROMs in the following sizes:
And of course the corresponding CMOS variants, as well as EEPROMs.
If the card is equipped with 4 pieces of 27512, this results in 2048kbit or the equivalent of 256kByte, which was already quite a considerable amount at that time. It was clearly more than the Commodore disk drive 1541 could store on a diskette or page.
The EPROMs could be mixed in size.
The real advantage of this card was that the memory was used contiguously. Many EPROM cards were limited by the fact that the respective program always had to fit completely into an EPROM. So it was not allowed to be bigger than the EPROM itself.
Particularly with many tools it happened then again and again that on each EPROM free place was unused, because for example still 2kByte were free, but the smallest program always had 3kByte.
The Brainy uses the EPROMs overlapping. Then the first 2kByte are written into the one EPROM and the remaining 1kByte into the next EPROM.
The card comes with a floppy disk, which is used to compile the corresponding menu and to generate the individual EPROM images.
The software takes some getting used to, but is functionally adapted to the Brainy cartridge.
After starting the software, the placement is configured first. It is not possible to change this configuration later without making all EPROMs again.
Since all the individual programs are stored across EPROMs and thus save space, a smaller EPROM cannot simply be exchanged for a larger one.
Mit den Cursor Tasten wird die Größe und der EPROM Slot ausgewählt.
With the cursor keys the size and the EPROM slot is selected. With the combination <SHIFT> + <RETURN> you get to the next configuration point.
The base address of the cartridge is now specified here. This must match the correspondingly set solder jumpers. By default the jumpers are set so that the base address is $DE00. If you have not changed anything at the solder jumpers, please do not change anything here either. Simply jump to the next point with <SHIFT> + <RETURN>.
You will now be asked which floppy drive is connected. Of course, there is less space on a 1541 than on a 1571, so the software knows when to change the floppy and how to distribute the images.
Select with the cursor keys and continue as before with <SHIFT> + <RETURN>.
The disc jockey
The next step is to determine which programs are to be placed on the module. Of course, only so-called “onefilers” can be stored. Software that loads from floppy disk does not work.
Here it is to be said in advance that one should prepare only the appropriate number of formatted empty floppy disks, but also the floppy disks with the appropriate programs, which are to be on the module.
My tip at this point would be to create corresponding floppy disks beforehand and to save the programs collected there in advance. Because one may play immediately in the wahrsten sense of the word Diskjockey.
So constantly change the individual disks. And one gets confused fast, where then which program is on it.
First insert the floppy disk with the program you want to put on the Brainy and press RETURN.
The directory is now displayed on the left side. If one would like to store a program on the Brainy, then this can be selected with the cursor keys and transferred with RETURN on the right side.
Once you have selected the desired programs from this disk, press <SHIFT> + <RETURN> again.
Again, the desired programs are selected.
And this is now repeated until either the EPROMS are completely filled. If you have collected enough programs and now want to create the EPROM images, you can continue by pressing the "←" key. Otherwise, select the next diskette with <SHIFT> + <RETURN> as before.
When you have finished collecting the programs by pressing the left arrow key (above the <CTRL> key and to the left of the <1> key), you will get an overview of what has been collected.
Here you can decide again what you want to put on the Brainy.
With the key Return the programs are taken over again on the right side. In this way you can also determine the order in which the menu is to be displayed later.
You can also vary the colors with the function keys F3/F4 and F5/F6. If you have arranged everything accordingly, then the next step follows with <SHIFT> + <RETURN> .
Now the start addresses of the individual programs can be adjusted if necessary. Normally you rarely have to change anything here. As usual, it continues with SHIFT.
Now comes the big gig as a disc jockey. Because now the source disks of the individual programs, as well as the disks for the EPROM images are constantly changed back and forth.
Who had put together the source disks accordingly before, is clearly in the advantage and saves also still the search for the appropriate disk.
At the end you get floppy disks with the corresponding EPROM images. These files are of course intended to be burned on the C64.
If you want to use a PC for this, you have to remove the first two bytes for the load address from the EPROM images.
Depending on the size of the EPROM, the files are also splitted (1a…,1b…, etc.). This was done because the large EPROM types would not fit completely into the C64’s memory and are burned in two passes. On the PC you can either copy the files together beforehand, or load them one after the other in the EPROM software (pay attention to the address!).
Everything necessary to rebuild the cartridge, as well as the software, I put on my GitHub account: https://github.com/DL2DW/Brainy_-_256k_Cartridge_for_C64