By contrast, Apple used 16 sectors for all 35 tracks.
As you can guess, track 1 is the track by the outer edge of the disk and track 35 is by the inner hole of the disk. Commodore decided to write more sectors ("blocks') to the outer tracks compared to the inner tracks. Apple and IBM formatted their disks so that each track held an equal amount of data, even though the there is a lot more surface area on the outer tracks of a disk than there is on the inner tracks. C64 disks had 35 tracks, just like Apple II disks, and used a 256-byte sector size, but there the similarities end. In the 1541 each side of the disk had to be formatted independently. The disks were encoded with Commodore's custom GCR encoding, similar to Apple's GCR but quite incompatible MFM encoding used by the IBM PC.
Like the Atari drives, you turn on your drive first, then the computer.
EMULATOR C64 NIB PC
The IBM PC used single sided drives for the first year of its existence. The disks used were standard double density disks, but the drive was a single sided drive like the drives for the contemporary Apple and Atari home computers. The 1541 had its own power supply and its own 6502 CPU, 16KB of ROM and 2KB of RAM, it was essentially a computer of its own.
EMULATOR C64 NIB SERIAL
The Commodore 1541 Disk Drive is an external 5.25" floppy disk drive which connects to the C64 via the 6-pin serial port. In Part 2 I will talk disk drives and disk images.īefore I can talk about the Ultimate-1541, I need to discuss the Commodore 1541 Disk Drive and how the C64 deals with floppy disks, the other major storage medium for NTSC C64 users. In Part I of this series, I covered some of the basic functionality of the Commodore 64 and my trials and tribulations in getting mine to work properly.
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