Commodore 8250LP
Commodore 8050 floppy-disk drive, with CBM 2001 PC
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| Manufacturer | Commodore Business Machines, Inc. |
|---|---|
| Type | Floppy drive |
| Release date | 8050: 1980 |
| Introductory price | 8050: USD 1695 (1980) USD 4,900 (2017 equivalent) |
| Media | 2x 5¼" floppy disk 8050: SS DD 8250: DS DD |
| Operating system | CBM DOS 2.5/2.7 |
| CPU | 2x MOS 6502 @ 1 MHz |
| Memory | 4 kB RAM 16 kB ROM |
| Storage | 8050: 521 kB/drive 8250: 1042 kB/drive |
| Connectivity | Parallel IEEE-488 1.8 kB/s |
| Power | 120 V 60 Hz 1 A fuse (8050 50 W ; 8250 60 W) |
| Backward compatibility |
PET, 4000-series, 8000-series, B128,Commodore 64, VIC-20 |
The Commodore 8050 and Commodore 8250 are dual-unit 5¼" floppy disk drives for Commodore International computers. They use a wide rectangular steel case form similar to that of the Commodore 4040, and use the IEEE-488 interface common to Commodore PET/CBM computers.
The 8050 is a single-sided drive, whereas the 8250 can use both sides of a disk simultaneously. Both use a quad density format storing approximately 0.5 megabyte per side. The density of media is similar to later PC high density floppy disks, but with the original 300-oersted coercivity used by double density drives. The 8050 and 8250 did not write with enough power to use 600-oersted PC high density disks reliably. As quad-density disks were rare even at the time that these were current models, users quickly found that typical double density floppy disks had enough magnetic media density to work in these drives.
These drives are not dual-mode, so they cannot read or write disks formatted by the more common lower-capacity Commodore 1541 or Commodore 4040 models.
Some variants of these drives exist. The Commodore 8250LP is the 8250 in a lower profile, tan-colored case. The Commodore SFD-1001 is a single-drive version of the 8250 in a Commodore 1541-style case (similarly to the Commodore 2031LP), often used by bulletin board systems for their physical similarity to 1541s and high capacity and speed.
Total Sectors: 2083 (4166 for the 8250)
The disk header is on 39/0 (track 39, sector 0), with the directory residing on the remaining 28 sectors of track 39.
Header Layout 39/0
The BAM (block availability map) begins on 38/0 (track 38, sector 0), and continues on 38/3. On the 8250, the BAM extends further to 38/6 and 38/9. The remaining sectors on track 38 are available for general use.
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