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>Connect a Hard Disk to your C64Details
>SWAP-Devicenumber-Buttons let your HD become drive 8 or 9Details
>Sub-directories and partitions, including 1541 emulationDetails
>Write Protect switch for more securityDetails


HD with manual SCSI detect screenshot
Up to 4 GB for your C64. Low Level Format Tool.

4 Player Interface

The HD series - easily connect a Hard Disk to your C64

When in the end of the 80's the first hard disks were available at high prices for Amiga and Atari, the question always was: Is there a hard disk for the C64, too? But Commodore made the C64 kernal just for a datasette and slow floppy disk access... The latter problem was solved with JiffyDOS. And meanwhile it is possible to connect an up to 4 GB large SCSI Hard Disk to your C64 just like you connect a 1541! (Plug & Play)
A SCSI HD controller together with the well-known 6502-based drive board type makes it come true. The HD can be accessed like a 1541 or FD-2000. The built-in HD DOS can understand all Commodore specific commands such as Rename, Scratch, Validate and also Block Read or Memory Write. This makes your HD as compatbile as the FD-2000. You can put thousands of one-part-demos and -games on it, or programs that use Commodore/JiffyDOS kernal for loading additional files (like many games). And as C64 programs and data are so tiny, even with a small HD of some 200 MB you have a practically endless storage.

The SWAP-Buttons - access from every program

A great feature of the HD series are its SWAP buttons: Once pressed, it SWAPs its own device number with your 1541's number 8, or 9, if the other button is pressed. Your HD is 8 (9) now, and since two devices with the same number wouldn't work, the device which previously had that number now has the original number of the HD. This is the very first time that the drives' intelligence is really used - the two computers inside communicate with each other - without your C64 noticing. This means that you can perfectly use your HD as a data storage - in all programs, even when they only support number 8. Put all your tools on your HD, including a full GoDot system, an endless number of games and more. Even multiload-games, which usually require drive number 8 (and given they use the Commodore/JiffyDOS kernal) can load all they need from your hard disk.

Subdirectories and Partitions

The CMD HD offers powerful and easy to handle sub-directories and partitions. Did you learn that a hard disk can not be devided into more than four (4) partitions? Forget about that. You can have up to 255 partitions on your CMD HD, with each partition a 16 MB (65535 Blocks) big. But there are also 1541-partitions, which have directory on track 18 and 664 Blocks free - which grants you even more compatibility. 1571 and 1581 emulation partitions are also available, and the CMD "Native" partitions can be as tiny or as large as you want.
In "Native" format, you can create subdirs by entering @MD:dirname and get into them with @CD:dirname. That's all! In the directory you have the same blocks free as anywhere else on your partition. The drive reserves extra dir blocks when needed.

Protect your hard disk

Although the CMD HD system is much more save than a common FAT32 Windows HD or Macintosh "B-Tree-Problem" hard disk, it can always be that you want to test something or whatever. For security reasons, you can always press the "Write Protect" button on your hard disk - and guess what it says when you try to write nevertheless: "26, Write Protect On"...

HD rear view HD inside
Serial, Parallel, SCSI. A peek inside...


The price of a CMD HD of 1 GB is $539. This seems not cheap, but given what it is (SCSI controller, 6502-based board with CMD HD DOS) and what it does it is ok. You can also try to get only the CMD HD controller, case and power supply, and install a SCSI HD yourself - this will save you some money.


The HD series hard disks are the most compatible possibility to connect a hard disk to your C64. The comfortable SWAP-buttons and the subdir- and partition features are simply great. But the compatibility also has its price: Connected via the serial bus, it is not as fast as one might expect from an HD (but still faster than an FD-2000). It is possible to connect it with a special parallel cable - then it's ultra fast! But this requires a RAMLink attached to the C64. Nevertheless it remains the ultimate storage for large masses. This also is important with some SuperCPU software.

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