The Commodore C64's External Diskette Drive
The external diskette drive for the Commodore C64 included its own integrated circuitry, with an independent processor and its own local memory. Commodore integrated DOS onto an EPROM inside the drive, so it wasn't necessary to load this code onto the C64 itself. In 1987, this 1541-II disk drive model cost about 500 DM (about $250); the first floppy disks for these drives cost about 100 DM ($50) each!
Floppy Drive 1541/1541 II
One programming efficiency unique to the period arose when savvy programmers offloaded various parts of the computing work for their programs to the 1541/1541 II external disk drives available at the time. This permitted them to achieve genuine "parallel computing." Lots of older users will no doubt remember programs that made music by moving these drives' read/write heads, or ones that could vary the intensity of the drive's LED actvity indicator light.
Floppy Drive 1541/1541 II
The 1541 drive used older, widely available, 5.25" double-sided, double density floppy disks. The drive itself, however, recorded on only one side of the media, with a maximum per-side storage capacity of 170 kilobytes. With the help of a special "disk notcher" (or some ingenuity and manual dexterity with a knife or hole punch) users could create "flippy disks" that could be turned over and recorded on both sides. To read from or write to the back side of the floppy, users had to pop it out and flip it over (hence the name "flippy disk"). Users then had to keep track of items stored on each side of these disks separately, and label them carefully to keep track of their contents.
Floppy Drive 1541/1541 II
This rear-view shot of a 1541 floppy drive shows an aftermarket reset switch wired into the device, which was handy when parallel processing on the drive would go south.
Floppy Drive 1541/1541 II Connectors
A rear view of the 1541/1541 II enclosure shows its various connectors. From left to right you can see the serial port that managed the link up with the Commodore 64, the interface port that allowed another floppy drive or printer to be daisy-chained to this device, a device indicator, a power input jack, and the on-off switch at the far right.
A Multi-Port Extension Card For The Expansion Port
This extension card plugs into the single expansion port inside the Commodore 64, and provides identical ports for up to three devices outside the enclosure. This particular board comes from German manufacturer Rex Datentechnik, and cost about 200 DM ($100) in 1987 when it was first introduced. On the left, you see a reset button and an on-off switch for the whole board; at the right of each expansion port, you see an on/off switch that controls each individual slot.
Another Shot Of The Rex Datentechnik Extension Card
This photo shows the extension card from the business end that plugged into the Commodore 64's expansion port. Note the high quality switches, components, and printed circuit board etching work.
The Expansion Card, Fully Populated
With three cartridges plugged into the Rex Datentechnik expansion card, you get a real sense for how this device was meant to be used. Gaming cartridges were by far the most common, but others implementing word processing, circuit design, music composition, programming, and other special functions were available. For an interesting look at a comprehensive list, see the Commodore C-64 Cartridge Rarity List.
Commodore C64
For its time, the Commodore C64 was quite energy efficient: its total power draw was only 15 watts. This home computer also was completely silent, since it used no fans.
Inkjet Printer MPS 1270
Only a few Commodore owners were able to treat themselves to this device: the inkjet MPS 1270 (A) printer from Commodore. It used the serial port to communicate with the C64.
