VC-1541
From C64-Wiki
Short name for the Commodore-disk drive VC-1541 (in Germany; international: VIC-1541, CBM-1541 or Commodore-1541), which is useable with 5,25"-disks. This disk drive has got only one reading/writing head. It is connected over a data cable with the serial bus to the Commodore 64. In consequence of the long production time of the C64, the VC-1541 has got various cases with and without power supply since 1983. The newer modells are called VC-1541C (since 1986) and VC-1541-II (since 1988).
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[edit] Features
The successor of the VC-1540, which can only be used at the VIC-20, can be used at the C64 and at some newer Commodore computers like C128/D/DCR, C16/116 and Plus/4. At the front of the case are 2 LEDs, a green for power control and a red for working status. When the red LED is flashing, an error occurred.
At the flipside of the case are 2 interfaces for serial data cable, the power-switcher and power-connector. At the VC-1541-II exist 2 DIP-switches to change the device number (optional 8). Depending on what modell the current supply was, this happend with a rubber connector or a power-supply.
One side of a 5,25"-disk has got in the VC-1541 174,848 bytes, which are 683 blocks, but only 664 blocks are useable.
The disk drive VC-1541 knows the following file formats:
- PRG program files (max. filesize approx. 200 blocks)
- SEQ sequential files (only useable with computer applications; max. filesize 168.656 Bytes)
- USR user-files (special format of a sequential file)
- REL relative files (only useable with computer applications; max. filesize 167.132 Bytes with max. 65.535 data sets)
- DEL deleted files (with hints or manipulation of the directory this file type can be viewed)
- If this char < stands after the file format, the file cannot be overwritten. It will be locked software-sided.
- If this char * stands after the file format, the file isn't properly closed. The deleting of this file is done only through the dos-command VALIDATE !
- Maximal number of files in a directory: 144
The data transfer rate is ~ 300 Bytes/s, but it will be higher by using a fast loader (up to ~ 10 KByte/s). The used version of Commodore-DOS is 2.6.
[edit] Technical Details
1541-1: 325302-01 (DOS V2.6 LoROM $C000-$DFFF),
901229-XX (DOS V2.6 HiROM $E000-$FFFF)
1541-C: 251968-01 (DOS V2.6 $C000-$FFFF)
1541-2: 251968-03 (DOS V2.6 $C000-$FFFF)
- Interfaces: Serial bus
- Total capacity: 174,848 bytes per disk
- Sequential files: 168,656 bytes per disk
- Relative files: 167,132 bytes per disk, 65,535 records per file
- Entries of a directory: 144 per disk
- Sectors per track: 17 to 21
- Tracks: 35
- Blocks: 683 (664 blocks free)
- Dimensions: 97*200*374 mm
- Weight: 5 kg
- Current supply: 100,120,220 or 240V with 50 or 60 Hz
- Power input: 25W
[edit] Disk Drive Control
The diskdrive VC-1541 can be controlled by following methods:
- With BASIC-Commands directly
- With BASIC-Commands in programs
- With special disk-Commands of the Commodore-DOS
[edit] With BASIC-Commands
- Format a disk (NEW):
OPEN 1,8,15,"N:Diskname, ID": CLOSE 1
or:OPEN 1,8,15: PRINT#1,"N:Diskname, ID": CLOSE 1
- remark: the diskname has got max. 16 chars and the ID has got 2 chars.
- Initialize a disk (INITIALIZE):
OPEN 1,8,15,"I":CLOSE 1
- Validate a disk (VALIDATE), that means the disk will be checking of correct data files and after that the directory will be refreshed:
OPEN 1,8,15,"V": CLOSE 1
- Copy files together (COPY):
OPEN 1,8,15,"C:NewFile=1.OldFile,2.OldFile,...": CLOSE 1
- remark: the charstring has got maximal 40 chars !
- Rename a file (RENAME):
OPEN 1,8,15,"R:New_Name=Old_Name":CLOSE 1
- Delete a file (SCRATCH):
OPEN 1,8,15,"S:filename": CLOSE 1
- remark: it can be used joker-chars like * (joker for any chars) or ? (joker for one char)
For example: OPEN 1,8,15,"S:*":CLOSE 1 all files of a disk will be deleted.
With comma (,) more than one file can be deleted.
- Overwrite a file (REPLACE):
SAVE"@:filename",8or
OPEN 1,8,15,"@:filename,S,W": CLOSE 1.
The REPLACE-Command is erroneous, so it could fail and you could lose all data of a disk. The better way is to first to use SCRATCH and after that the BASIC-command SAVE.
- These BASIC-commands can be used with the disk drive, too: CLOSE, GET#, INPUT#, LOAD, OPEN, PRINT#, SAVE and VERIFY.
[edit] Hints
- The VC 20-mode at the VC1541 activated:
OPEN 15,8,15,"UI-":CLOSE 15 - The C64-mode at the VC1541 activated:
OPEN 15,8,15,"UI+":CLOSE 15
- device number (8-15) can be changed temporarily by software with:
OPEN 15,8,15:PRINT#15,"M-W";CHR$(119);CHR$(0);CHR$(2);CHR$(device number+32)+CHR$(device numver+64):CLOSE 15
- device number (8-11) can be changed permanently by hardware over DIP-switches ( 1-2 or A-B):
| Device number | DIP-1/A | DIP-2/B |
|---|---|---|
| 8 | on | on |
| 9 | off | on |
| 10 | on | off |
| 11 | off | off |
| top: on - bottom: off | ||
- At some modells, that don't have any DIP-switches, the device number can be set by manipulating the terminal tag. The terminal tags are called "Device Jumpers" at the board of the diskdrive.
[edit] Content of the test-/demodisk
Side 1:
13 HOW TO USE PRG (engl. instruction 1.part) 5 HOW TO USE TWO PRG (engl. instruction 2.part) 1 C-64 WEDGE PRG (Utility-Starter C64) 4 VIC-20 WEDGE PRG (Utility-Starter für VIC/VC20) 4 DOS 5.1 PRG (Utility-Mainprogram) 11 COPY/ALL PRG (Copyprogram) 9 PRINTER TEST PRG (Printertest) 4 DISK ADDR CHANGE PRG (Change device number by software) 4 DIR PRG (Easier using of Disk-Commands) 6 VIEW BAM PRG (BAM-Viewer) 4 CHECK DISK PRG (Diskcheck with VALIDATE) 14 DISPLAY T&S PRG (Block-Viewer in Decimal or Hexadecimal) 9 PERFORMANCE TEST PRG (Floppy-Check) 5 SEQUENTIAL FILE PRG (Program example for SEQ-files) 13 RANDOM FILE PRG (Program example for special DOS-Commands) 558 BLOCKS FREE
Remark: The content of the test-/demodisk can change a little bit depending on the year of construction or modell.
[edit] Links
| Wikipedia: Commodore_1541 |
