VC1551
The VC 1551 (development name SFS-481 ) is a 5¼-inch floppy disk drive for the 264 home computer series (C16, C116, Plus / 4) from Commodore . It came on the market in 1984 . Commodore had planned an interface to enable the use of the 1551 with the C64, but this was never released.
The 1551 is very different from the other models in the VC15xx series. The circuit board is designed completely different, and the drive mechanics are less sensitive than those of the VC1541 . Most noticeable, however, is the connection: A parallel cable leads from the floppy to a connection box that is permanently connected to it and is plugged directly into the module port of the computer. This concept was called the TCBM bus. Since the module port of the 264 was designed differently, the 1551 could not be used on the other Commodore computers, such as the VC-20 , C64 and C128 .
Internally, the VC1551 works with the usual Commodore DOS as the operating system . Compared to the serial CBM bus , the transfer speed has been increased by a factor of about 4, a modest value for parallel data transfer. The data transfer speed of the VC1551 is around 1 kB per second, which is around three times as high as that of the VC1541.
The floppy disk drive uses Group Coded Recording (GCR) and contains a 6510T processor as a controller. The 6510T processor is a specialized version of the 6510 processor used in the C64 and is only used in the 1551. The DOS used limits the number of files per disk to 144, regardless of the number of free blocks on the disk, since the directory has a fixed size and the file system does not allow subdirectories. The DOS of the 1551 is compatible with that of the VC1541.
The VC1551 does not have any DIP switches to change the device number of the drive. If you added more than one drive to a system, you had to open the case and cut a wire on the circuit board in order to permanently change the drive number, or to change the drive number via an external, self-soldering switch. A maximum of two 1551 can be operated on one computer.
With the end of the 264 series, the construction of the 1551 was also discontinued, as it could only be connected to these computers. The TCBM bus was also discarded.
Web links
- Commodore 1551 on c64-wiki.de
- Commodore VC 1551 detailed description on kuto.de
- Test report in '64 magazine 09/1986, pages 24-25
