mdbasic.bin ROM file crashed the C64?

[unebonnevie]

Hi,

I am giving this a try as a cartridge format on the C64. I made the cartridge from this site https://github.com/SukkoPera/OpenC64Cart16K. I used the below commands (cartconv utility from the VICE emulator) to make the mdbasic.bin file off the mdbasic.prg file.

First convert PRG to CRT format.

cartconv -t normal -i mdbasic.prg -o mdbasic.crt

then convert the CRT format to BIN format by stripping out all VICE stuff.

cartconv -i mdbasic.crt -o mdbasic.bin

mdbasic.bin is produced exactly 16KB, that is, 16384 bytes. I flashed it to the EEPROM 27C512 successfully.

But the C64 crashes with a blank screen when I use the cartrdige, that is, the mbasic.bin. I am wondering 1) if you had tried the cartridge format for MDBasic. 2) that I am not converting the PRG to the BIN file correctly.

Attached is the zip file with the .PRG and .BIN and .CRT files.

I tried VICE by loading the CRT file, and it crashes exactly like my cartridge with the .BIN file programmed into the 27C512 EEPROM. Please see attached image.

Thanks for any tips.

MDBASIC.zip

[unebonnevie]

So, I used VICE and had it run YOUR distributed CRT file, which is like 24KB (much bigger than the one I produced mentioned in the original post), and it works fine. Please see image below.

Uhmmm...I am not creating the correct .CRT and .BIN file off your distributed PRG file.

Update:

Given the below. Basically, I took your distributed CRT file and executed the cartconv command from VICE to convert it to pure ROM binary BIN file, and its size is 24576 bytes, much bigger than the one produced in the original post. So, I did it wrong somehow.

I think I would need a Magic Desk cartridge to run MDBasic as ROM cartridge format, because mdbasic is larger than 16KB. Is that it? Thank you!

c:\emulators\VIC20>cartconv -i c:\temp\mdbasic_orig.crt -o c:\temp\mdbasic_orig.bin
Input file : c:\temp\mdbasic_orig.crt
Output file : c:\temp\mdbasic_orig.bin
Conversion from Magic Desk .crt to binary format successful.

c:\emulators\VIC20>dir c:\temp\mdbasic_orig.bin
Volume in drive C is OS
Volume Serial Number is 0C9A-784C

Directory of c:\temp

07/30/2026 05:18 PM 24,576 mdbasic_orig.bin
1 File(s) 24,576 bytes
0 Dir(s) 228,541,554,688 bytes free

[bowren]

Yes. I used the Magic Desk ID for the cartridge to get it to work. I manually created the CRT image by writing a python script to include the cartridge metadata. I will upload the python script to this repo so you and others can make your own CRT files from PRG files.

The python script is called prg2crt.py. Below is a an example of executing it in the directory where the PRG file resides:
python3 prg2crt.py mdbasic.prg mdbasic.crt

[unebonnevie]

I will upload the python script to this repo so you and others can make your own CRT files from PRG files.

Thank you so much! Ok. I will have to hunt down a Magic Desk cart PCB and make one. The normal 16KB cart for the C64 won't do it, because mdbasic.bin is larger than 16KB.

[unebonnevie]

I built a MagicDesk cart and made the mdbbasic.bin file off your distributed mdbasic.crt file, using VICE's cartconv command mentioned earlier. The BIN file produced has no VICE meta data in it. Anyway, still not able to run from the cartridge. I posted msolajic/c64-uni-cart#7 for help :-) If you have any idea, please let me know. The BIN file produced is 24KB, which is attached for reference.

Thank you!

mdbasic_crt_and_bin_files.zip

[unebonnevie]

Update:

So, after some researching, since I am NOOB at C64 various cartridge formats, I need to make the mdbasic.prg file to a Magic Desk compliant/compatible binary file. I use the tool at https://github.com/Feandreu/mdeskcrtgenfsp (or https://bitbucket.org/zzarko/magic-desk-cartridge-generator/src/master/).

I got the below BIN attached file generated. It's generated to even 64KB (exactly 65536 bytes).

I loaded this generated BIN file to VICE and it works, but it still does NOT work when I flashed this BIN file to a 27C512 EEPROM for the Magic Desk compatible cart (see msolajic/c64-uni-cart#7).

Urgggg.... :-)

mdbasic_magic_desk_generated_bin_file.zip

[bowren]

I put the CRT image onto my Kung Fu Flash cartridge and it works fine. Kung Fu Flash remembers the last loaded CRT and automatically loads it on power up just like a regular cartridge.

Are you using the latest version of Vice? I noticed your installation directory is named "VIC20". Will the cartconv program will generate a compatible BIN file for a C64. MDBASIC resides in RAM between $8000-$BFFF (with $A000-$BFFF "under" ROM). The cartridge must copy the binary to this location. The program to do this copy is included inside the CRT.

[unebonnevie]

Hi, yes, your CRT file and the BIN file I created off your CRT file work fine on the VICE version that I installed. (I named the folder as "VIC20" but it is VICE.) However, when I tried to flash the BIN file I created to a Magic Desk cartridge, it does not work at all. It's not your stuff. Something wiht the Magic Desk cart that I made. See msolajic/c64-uni-cart#7 for more detail. Sorry for the confusion.

Thank you.

[bowren]

Try installing the jumper (or solder a short) on the jumper labeled "GAME" on the front of the PCB. This will match the CRT setting (see python code). Let me know if that works.

[unebonnevie]

Try installing the jumper (or solder a short) on the jumper labeled "GAME" on the front of the PCB.

That didn't help. Let's see what the MagicDesk cart creator has to say in the issue (msolajic/c64-uni-cart#7) I reported. Thanks for the help and for taking the time to write MDBasic!

[bowren]

I rebuilt the CRT without the GAME setting in the metadata and it has no effect in VICE but might affect actual hardware. I converted it to a BIN file and uploaded the file to this repo. Remove the GAME jumper and then give this a try: mdbasic.bin

[unebonnevie]

I rebuilt the CRT without the GAME setting in the metadata and it has no effect in VICE but might affect actual hardware. I converted it to a BIN file and uploaded the file to this repo. Remove the GAME jumper and then give this a try: mdbasic.bin

Thanks! I appreciate that. I just tried your rebuilt BIN file with and without the cartridge's "GAME" switch shorted. Same problem. The Magic Desk cart maker hasn't responded.

I had checked and rechecked everything. Thanks again for your efforts/help.