Commodore 64 Disk Drive

A Commodore disk drive is used to record data onto a 5 1/4 inch floppy diskette for later retrieval. The data is contained on tracks and occupied in sectors.

When the disk drive is first powered on, software within will complete a self check for a few seconds to ensure everything works properly. This will then active the red led light on the drive and later activate the green light to indicate that the startup was successful.

The 1541 disk drive can accept diskettes that are the size of 5 1/4 inch. In order to load the contents, the DOS CBM start up files must be copied. If the drive fails to load a file the drive will throw an error indicating that the file was not located. Also if the drive fails for some reason (faulty drive, bad serial cable, etc) then the mssage ‘DEVICE NOT PRESENT ERROR’ will be displayed on the screen. Be sure not to remove a diskette while the red light is on or you could permanently wipe out its’ contents.

Disk Drive Internal Parts

A serial bus interface is built within the unit manufactured by Commodore. According to the book the Commodore 1541 User Manual “the signal of this bus resemble the parallell IEEE-488 interface”, which was used on their PET line of computers. The only difference is that one lead wire was used to transmit data across instead of utilizing all eight lines.

At the back of the 1541 Commodore Disk Drive are several areas of interest. Starting at the left going to the right, is the on/off switch for the power supply. Next to this is the port that handles the power supply connection.

Immediately to the right of this is the fuse control which is conveniently located in case you ever need to do an emergency replacement.

Above the fuse control are the serial interface connectors (often referred to as IEEE or IEC bus). This port is used to plug in a disk drive or printer. My disk drive has two connectors so that they can be daisy chained together. A common term that means to connect one drive or device to another.

5 1/4″ Floppy Disk Details

A diskette is covered by a plastic coating that surrounds the internal parts. The hub is the center part that is accessed by the drive. When the disk is in the drive, a spindle occupies the space and clamps the edges.

A floppy disk can maintain a capacity of 174,000 bytes of data for storage and can write close to 144 programs onto a single diskette.

The read/write head manages the writing of data to a diskette. Be aware that these can get dirty over time, and need to be cleaned with 91% isopropyl alcohol using a cotton swab. Also the head rails may require lubrication from time to time, as well as the write protect sensor on the drive.

When using a floppy disk it is very important to take care not to take the circular part in the center or try to remove it from the plastic sleeve. Also insert the disk slowly into the Commodore 64 disk drive to avoid bending it. This will result in longer preservation of your diskettes.

Toward the bottom of the disk is an opening in an oval shape known as the access slot. Once the disk is safely in the drive , this area is read by the read/write head which follows up the center to meet the edge of the diskette.

To learn how to load programs and save programs using the disk drive, be sure to check out the article called WinVice versus Commodore 64.

Disk Drive Directory

In Basic, the Commodore 64 computer when used with a disk drive contains the ability to load a disk directory into memory due to ROM chip access on the drive. For further information, check out the article called Commodore Disk Directory.

As mentioned earlier, a Commodore 64 diskette needs to be formatted to read and write data to the tracks. You can use the commands below for this.

OPEN 15,device #,15,”Ndrive #:diskette name,id”

For this session we reviewed the purpose of a disk drive, some safety tips with floppy diskettes, and how to format a disk for use. As always I hope this article was informative. Please be sure to bookmark this page, share it with your friends, and leave any comments or questions you may have. Thank you!