Monday, 23 October 2017

IRQHack64 impressions

The IRQHack 64 may not be as widely known as the SD2IEC disk emulator or the Ultimate cartridge. The IRQHack loads Commodore 64 programs (prg) super-fast and does small cartridge (crt) files too. I also hear about a possible serial transfer between a PC and the C64.

As can be seen, IRQHack uses ready-made Arduino components (A Pro Mini or a variant). The IRQHack is developed and prototyped by Nejat Dilek, with schematics and PCB design by Özay Turay.

I bought this one as assembled inside a neat 3D-printed casing, with the EPROM burned beforehand. The only thing left to do was to format a FAT32 microSD card and put the necessary files there. Without a prg loader menu, the cart doesn't do much.

The archive has two separate file menu alternatives:


One is needed in the root folder of the SD card. The I_R_on menu is simpler, the wizofwor version has a moving graphics effect. Both have background music which I guess is ok for showing that the sound works, but it feels a bit unnecessary.

Up and running

Pressing the button rapidly, the menu will be activated. Pressing it for a tiny bit longer generates a normal reset. Pressing it 2-5 seconds (it gets complicated!) the current selected software can be made to autostart the next time the computer is powered on.

Using the cartridge reset or reset from a separate device did not result in the prg autostart. I guess it could bring complications, but an auto-run from the reset would be useful too.

The mess in the right is from running it as a prg from the other menu for shows. It doesn't do that really.
The menus don't have much functionality in them. Both menu alternatives use + and - keys for up and down, which I felt was slightly clumsy, arrow keys might have been better. The SD file folder structure is supported.

I also noted that some game prgs crashed, although they worked with the SD2IEC. I've not looked deeper to this, but I did try a different C64 and removing the peripherals, with no result.

For the single purpose of loading prgs fast, IRQHack is very handy. It's also nice to boot directly to the program you want. Make the C-64 boot directly to a SID tracker, image editor, or a comprehensive file menu system?

Not that I can get it to do anything.
I thought about comparing the IRQHack with the SD2IEC but it's a bit pointless as I can connect both at the same time. The IRQHack potentially complements the SD2IEC setup, except as I can't have the Final Cartridge or Action Replay I lose monitor and fastload functions.

As a small consolation a RAM version of Jiffydos can give a fastloader at least, but in this form it can have some limitations. It could load a single-file game from the SD2IEC rather nicely, but on another occasion a program failed to run properly with the Jiffydos in RAM. It can still be helpful in supporting common file operations.

As the IRQHack does not do disk emulation, and the cartridge image loading is limited, it is far from an end-all solution for your favorite games and demo library. It might fall uncomfortably between Ultimate (which I still don't personally own) and the SD2IEC, but it is a reasonably cheap & nice tool for someone like me who dabbles in C64 code and graphics cross-development.

Until the next time

These were my surface impressions, I'll get back to the serial transfer function when I have a USB-TTL serial cable for the Arduino pins. In my eyes this would improve the worth of this cartridge a lot if the transfer works as smoothly as I hope it would.

In the future I might also get into the sources a bit more. I installed 64tass assembler to my Linux, and using the .bat files as guidance, I had some success with compiling irqhack64.prg. 

The version I compiled could not in the end access folders from the SD card so I'll forget about it for a while. It might be that the C64 menu program, the EEPROM stuff and Arduino code all have to be corresponding versions (the included script compiles everything) and I currently don't have the gear and patience to do all that.

My current C64 setup

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