After releasing the C128, the first drive Commodore produced for this computer was the 5,25"-Floppy 1570 (also Commodore-1570 or CBM-1570). Production started in 1985. It is a mix between a 1541 and a 1571. The 1570 has like the disk drives VIC-1540/1541/1551 one head for reading/writing. However it can handle two Read/Write formats. First the usual GCR-format from Commodore and second the MFM-format (for CP/M software) which is also used in a PC. The drive will be connected via the serial bus to the home computer C64/C128/D/DCR, plus C16/116 and Plus/4 resp. VIC-20. The mains adapter integrated like in the 1541. The power supply is realized through a rubber connector. The Disk will be kept with a latch in the drive. The device number (8-11) can be changed via DIP-switches. But this works only, if the cover is removed. The 1570 contains the Commodore-DOS 3.0 or 3.1. Furthermore the data transfer with the C128 in the so called Burst-Mode is about 10times (3.000 Bytes/s) faster than the disk drive 1541.
Recording in the GCR format (Group Coded Recording).
On each Disk there are 174,848 bytes available, from which 664 blocks are usable and the maximum amount of entries in the directory is limited to 144.
The disk drive 1570 recognizes the following file formats:
- PRG program files (max. file size 200 blocks)
- SEQ sequential files (for data storage of applications; max. file size 168.656 bytes)
- USR user files (special form of sequential data)
- REL relative files (also for data storage of applications; max. file size 167.132 Bytes with max. 65.535 records)
- DEL deleted file (can be made visible with tricks resp. manipulation of the directory)
- If the character < is displayed behind the file name, the file has a write protection by software.
- If a * is displayed, the file seems not to be closed properly. This can be fixed by using the VALIDATE command, NOT the SCRATCH command.
Recording in the MFM format (Modified Frequency Modulation).
An unformatted disk will be recognized with 500.000 Bytes, although depending on the used sector size (128/256/512/1024 Bytes) only 130/160/180 or 200 kByte can be used. The maximum number of tracks is 40 from which depending on the sector size (128/256/512/1024) 26, 16, 9 or 5 sectors will be used.
- Chips used: 6502A (CPU) running at 1-2MHz, 6522, 6526
- ROM with 32KByte: 23256
- RAM with 2 KByte: 6116
- Gate Array: 64H156/64H157
- Analog switch: R/W hybrid circuit
- Disk-Controller: WD 1770
- Dimensions: 97*200*374 mm
- Weigth: 3,5 kg
- Power supply: 100,120,220 or 240V with 50 or 60 Hz
- Power input: 25W
Memory mapping and Test-/Demodisk of the 1570
The memory mapping and the content of the Test-/Demodisk of the 1570 is same than for the disk drive 1571.
Controlling the disk drive
The disk drive 1570 can be controlled through the following methods:
- Basic commands in the command mode
- Basic commands in programs or programs
- Special disk commands