Commodore 1571
The floppy drives VC 1570 and VC 1571 5 ¼ -inch drives for the home computer Commodore C128, but can also be used on the C64. Internally, they are working with Commodore DOS version 3.0 or (in C128DCR ) version 3.1.
- 2.1 Internal Drive in the C128D
- 2.2 Internal Drive in C128DCR
- 2.3 1570
- 3.1 1572
- 3.2 1571 II
Characteristics
From the case shape to the 1571 the design of the C128 adapts (ie looks like a larger 1541 II); the 1570, however, has the same beige housing as the 1541C. The drives run noticeably quieter than older models and also produce less heat, so that - in contrast to some 1541 - despite the integrated power supply no thermal problems ( misalignment, etc. ) occur.
The drives have two modes: 1541 - ( emulation ) and 1571 - or 1570 - ( native ) mode. By default, the former is active and the internal CPU 6502 is clocked at 1 MHz at switch on, the drive switches to the native mode of 2 MHz clock, as soon as a C128 accesses.
On the C128 157x implemented significantly faster data transfer to a computer than the VC1541 (about 7 × faster), including a hitherto unused line of the serial bus for hardware handshaking is used (so-called fast serial transfer). A C64 can be upgraded for this data transfer later on the hardware side. Also a special transmission mode (" burst mode " ) is this hardware configuration allows, which is faster than the standard transfer between C64 and 1541 up to 30x and demands on computer side special programming.
On C64, VC20, etc., so in 1541 mode, the drives like a 1541 ( which can be accessed by programming here on the second disk side and MFM formats, but only with 1541- speed ) behave. As used in almost the same DOS 1541 mode, as with the 1541, the majority of C64 rapid charger works (including that of the Action Replay 6 and the Final Cartridge 3) with the 157x, only very fail hardware or timing specific tricks.
As the VC1541 normally uses the VC157x GCR recording method. In addition, it has an additional controller (WD 1770 ) for the MFM recording method and therefore can also read the usually recorded in this procedure CP/M- and MS -DOS disks. Thus, it is possible to files of a conventional PC to C128 and copy vice versa (for example, with the programs "Big Blue Reader " and " Little Red Reader "). However, this is only for PC and PC / XT disks with a maximum of 360 kB capacity possible, the HD disks of the PC / AT and later models with 1.2 MB can not read the VC157x.
Data capacity
While the 1570 as the 1541 has only one write head and floppy therefore, like that can describe one side only twice by inversion, has 1571 two heads, so that disks can be used on both sides. Because of the reverse rotation direction and the four lanes wide displacement of the head on the disk back, the two methods "Turn " and "second head ", however, are not compatible with each other; on the VC1541 generated double- sided insert disks must also be turned over to the VC1571.
The mechanical maximum capacity is 400 kB, wherein the native Commodore Format formats the disk with 340 kB ( 2 x 35 tracks, 1360 block of 256 bytes ). (For comparison: IBM DD 5.25 " disk first 320 kB, from MS DOS 2.0 360 kB. )
Under normal circumstances, data are available for them each 254 bytes of block 1328, ie 337 312 bytes per disk or just 330 Kbytes; the rest is used for the file system.
In addition, the format of the VC1541 ( 35 Tracks à 683 block = 170 kB, usually including just under 165 kB usable) be read, written and formatted.
Variants
The 157x is available as a standalone drive in Beige ( with integrated power supply ), the 1571 also installed in the C128D and C128DCR.
Internal Drive in the C128D
The drive in the (plastic) C128D equivalent to an external 1571 without housing. The controller board, which is independent of the main board of the C128, has been changed from the board of the external 1571 in layout and size, however, circuit and components are identical. The first version of the CBM DOS 3.0 had problems reading, sectors of the second disk side of Discs in 1571 format ( repositioning of the read-write head after writing a sector of the second disk side ). This bug has been fixed in later version of the CBM DOS. Also the drive, as well as the external 1571 copy-protected floppy disks in 1541 format can not be read in certain cases. Also work some quick charging programs that are designed for the 1541, not.
Internal drive in C128DCR
As part of the redesign of the main board of the C128DCR (CR = cost reduction, with the aim of reducing the number of required components) are still independent in the C128D controller board of the internal 1571 drive was integrated into the newly designed motherboard of C128DCR. An essential feature of the integrated controller is the use of two new modules that control the drive itself, and summarize various modules of the previous circuit. With this drive, a new version of the CBM DOS 3.1 was shipped, which also includes an adjustment to the two new controller modules in addition to a troubleshooting over older versions. Not only will this new CBM -DOS version, but also the new blocks in some cases led to an extended incompatibility with 1541 drive, especially in C64 games with floppy quick charger or copy protection.
1570
The 1570 consists of the board of 1571, a drive manufacturer Alps with only one read-write head, white front panel painted in brown plastic and a light barrier for the index hole detection ( largely identical to the drives of Alps in the 1540/41 ), an additional board with a power supply assembly ( electrically similar to the power supply module of the 1540/41 ) and the housing of 1541C in white color. The firmware ( CBM DOS 3.0) was derived from firmware 1571 and mainly includes the adjustments for the drive with only one read-write head.
The 1570 was at least in Germany, in contrast to 1571 at the beginning of the sale of the C128 available. Commodore developed the 1570 probably only because 1571 was significantly behind schedule and the boards and boxes for 1571 should not be endlessly produced in stock; Furthermore, the 1541 series was for the C128 no longer appropriate, since this should be a professional computer have a drive starting at launch, which was faster and (important for CP / M) MFM -capable.
Unrealized variants
1572
At CES 1985, the 1572 was introduced, in which it was a disk station with two 1571 drives that reminded visually of a double-wide in 1571 with two shafts and knobs. It is questionable whether even working prototypes exist of this drive.
1571 II
There were plans a " 1571 II" with a separate power supply to bring out (similar to the 1541 II ), also with the slightly adjusted, but for DOS 3.0 and the versions for the less compatible DOS 3.1 of C128DCR 1541- series would have to work. Because Commodores fixation on the Amiga computer this drive no longer appeared but.
JiffyDOS for the 157x
For the 157x - series there is, as for other CBM drives, in addition to other third-party DOS ROMs also remedial real JiffyDOS, which no longer occur, among other things above bugs in the C128D and the compatibility of the drives is increased in C128DCR.
Overview Specifications VC 1570/1571
- Disk type: 5 ¼ inches
- Recording Format: GCR, MFM, Unidirectional (1571 also double-sided ), Double Density
- Formatting: 35 ( 1570) or 2 × 35 (1571 ) tracks 17-21 sectors per track, 256 bytes per sector (of which each normally 254 bytes available for data)
- CPU: MOS Technology 6502A with 1-2 MHz
- RAM: 2 KB
- ROM: 32 KB
- Transfer protocols: standard (such as 1541) and Fast Serial and burst mode (as in 1581, with C128 )
- Interface: CBMs " serial IEEE - 488" (CBM bus, via DIN connector )