„SD2IEC” Interface – Is It Worth?


Time passes by... Yes, but despite that, everyone (most probably) remembers the times when a disc drive was kinda of a dream. Not mentioning a real Holy Grail – a 1581 or even a Hard Drive.

Some of us could bought their C64 together with a standard available floppy drive, some of us were simply not able to do so, due to a smaller pocket-money size. Thus, when the need is the mother of all inventions, here too, we had seen many floppy-drive substitutes, which helped us to enlarge and widen our commodore software collection. With time, floppy-drives become more cheap, but still, the disk-space, access to data and disc-access speed were a little bit outdated to those who have already got used to the PC HD comfort. The homebrew inventors were looking for how to mix an old-school drive with the electronic based on a new memory-drive solutions, with of course 100% FULL 1541 compatibility. Every game, tool and demo virtually MUST run on it.

Many projects have seen the day's light such as IEC-ATA, CIA-IDE or other ones such as a directly connected PC to our breadbox (making a PC like a C64's HDD). Many solutions did not last long or even went into the oblivion pushed away by better ones, not necessarily cheaper.

To finish this, perhaps quite a long introduction, here below I wish to review for you a device, which I think needs some attention and is very interesting. The device I a talking about is an interface entitled „SD2IEC”, which besides being a little bit oldish, and a few drawbacks, still 'till today is found as a very popular replacement of good, old Datasette or a Floppy Drive.

What is a SD2IEC? Well, it is a device, making possible a PC to C64 data transfer thanks to a SD/SDHC/MMC memory card. The card itself must be formatted using FAT12/16/32 file systems.

As the name gives it, this solution is connected to the IEC serial port, so exactly there, where a floppy drive has its port. Thus our breadbox, using a standard SD card, is able to run one-file programs (.prg and .p00) as well as floppy-disk images (.d64 and M2I). The SD card can contain directories (within directories) with programs names. The SD2IEC is based on Atmega-644 microcontroller, which emulates (to some level) 1541 floppy drive. The majority of the most frequently used commands, such as: LOAD, SAVE, OPEN, GET and etc., are fully emulated.

The SD2IEC interface can be attached to our C64 with a number „8”, as we are used to use it. Well, in fact, any disk number from 8 to 11 may be used, albeit if one want to use a number different from 8, that would need some soldering skills (at least the v1.2 needed such a changing). A small ground-connector should be added.

And if we are talking about soldering, one may do another wise trick – add an external reset button, which was not 1541's standard nor SD2IEC's feature. One can do even more – can add a button (that's new, I must say) to allow a user an easy directory swap (one for scrolling up, another one for scrolling down).

These, here above mentioned, solutions, are quite handy, in my personal opinion. After the C64's reset the SD2IEC's stays at the very same directory point where our work was stopped. To return to the root directory, both solutions can be used - SD2IEC reset or using the new-soldered directory switches.

If one is manually gifted, the SD2IEC reset may be soldered together with the internal C64's reset. Or even put inside our breadbox. ;-) Why not?

Everything works well with Final III cartridge, Turbo Disk and the Jiffy DOS „accelerator”. But the hardware, that's not all what make that thing successful. What is important is software as well as the easiness and comfort of using. Having a bare, stock C64 and to avoid typing all those long and clumsy commands, a file commander is the only solution. One of the most popular is called „FIBR”, but there are many, many of them available.

It also happens (quite rarely thou) that the SD2IEC's fathers bump into the Atmega's code. As a consequence, new patches are released. It is not a problem thou, cause the only thing to do is to copy the corrected SD2IEC software to the main SD card's root directory and... voila. :) Everything is done automatically – as soon as the C64 is on, the new package is decompressed and copied to the Atmega's memory. And at the blink of the eye, the interface is ready to be used.

As it was mentioned a few paragraphs above, the 1541 floppy is only partially emulated. That also means that without any additional accelerator, the data transfer is slightly faster than the original data transfer.

What is left, is a small recapitulation. To sum it up. If one is not having too many spare quid, and wishes to have a quite big C64 software library (games, tools, or other software), one can spent about 30-40 Euros. To buy the SD2IEC interface. But if one is more demanding and besides of some excellent one- or multiple-floppy games, if one loves to watch trackmos and use all the software which pushes the 1541 floppy to its limits, the „1541Ultimate” is a better solution, in my opinion. Thus some extra money is needed ;). The „1541Ultimate”, despite being quite expensive (costs about 130 Euros), fully, fully emulates C64's floppy drive and, what is not neglectful, has built-in REU.

Another worthy alternative is an UK1541. But... you will read about it in another article.


Translation: Sim / Wanted Team, Lamers, Resistance, Titan...