Commodore 1581 Disk Drive: The Essential C64 Companion
◆ Revised
The Commodore 1581 was Commodore’s 3½-inch floppy disk drive for its 8-bit computer range, offering substantially greater storage capacity than the familiar 1541 while retaining compatibility with Commodore’s serial disk system.
Using double-sided, double-density disks, the 1581 provided more than 800 KB of formatted storage and incorporated its own processor, memory and floppy-disk controller. It also supported features such as fast serial transfers and burst commands when used with compatible systems.
This article provides an overview of the Commodore 1581, its technical specifications and internal hardware, together with original user guides, service documentation and other useful reference material.
On the bookshelf
On the Bookshelf brings together original Commodore 1581 manuals, service documentation and other period reference material. These resources provide a deeper look at how the drive was intended to be used, maintained and understood, making them useful companions for collectors, restorers and anyone exploring Commodore hardware today.
Commodore 1581
User's Guide
(read online)
Commodore 1581
Specification [DE]
(read online)
Commodore 1581
Service Manual
(read online)
Sams Computerfacts 1581
Technical Service Data
(read online)
Notice: Resources are hosted by the Internet Archive, which is independent of this website.
Commodore 1581 Technical Specification
1581 storage capability
- Total unformatted capacity 1 Megabyte
- Total formatted capacity 808,960 bytes
- Maximum sequential file size 802,640 bytes
- Maximum relative file size ~800K
- Records per file 65,535
- Files per diskette 296
- Cylinders per diskette 80
- Logical sectors per cylinder 40 (0-39)
- Physical sectors per cylinder 20 (1-20)
- Free blocks per disk 3160
- Logical bytes per cylinder 256
- Physical bytes per sector 512
Integrated circuits used in the 1581
- 6502A microprocessor
- 8520A I/O processor
- 23256 32K bytes ROM
- 4364 8K bytes RAM
- WD177X floppy disk controller
Keeping your Commodore 1581 running
Original Commodore disk drives are now decades old, but replacement parts, cables and modern storage accessories can help keep a C64 setup practical. The following resources cover both restoration needs and newer alternatives for owners who still use original hardware.
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Writer's Notes
Reader Guide
The following material expands on the terminology, historical context, technical concepts, and related reading connected to this article.
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Disclosure
This article is provided for historical and general informational purposes. Specifications, compatibility and operating behaviour may vary between Commodore models, revisions, software and third-party hardware. Links to external sites do not constitute endorsement.