After previously dissecting the firmware of alternate C64 disk drives, let’s now look at the hardware of one: This is the Blue Chip BCD/5.25.
The BCD/5.25 is a clone of the 1541. Its hardware is equivalent to the Commodore 1541, and it even uses an obfuscated version of that drive’s firmware.
My device came in the original box. It was bought at Sears for $179.99 (in 1986).
- COMMODORE COMPATIBLE FLOPPY DISK DRIVE BCD/5.25
- Works with Commodore 64 and 128, SX64, C15, Plus 4, and VIC 20.
- 100% Compatible with Commodore Computers
- Runs 1000’s of programs written for Commodore
- Faster, More Accurare, and Less Expensive than Commodore.
- BLUE CHIP ELECTRONICS, INC. • 7305 W. BOSTON AVE • CHANDLER, AZ 85226 • (602) 961-1485
- Commodore Interface. 100% Compatible with the Commodore 64, Commodore 128, SX16, C16, Plus 4, and VIC 20. The cable’s included free.
- Rugged construction. Virtually bulletproof. Fully shielded, high impact case. Comes with a Full Year Warranty.
- Mass Data Storage. Stores over 174,000 bytes and 144 separate directory entries per diskette.
- Key Latch. A lightly engineered precision disk centering system guarantees exact disk positioning everytime. State-of-the-art Ceramic heads, and a steel band positioner eliminate almost all read/write errors.
- External Power Supply. Because the power supply is outside the drive, the BCD/5.25 runs 24 hours a day without overheating. (No more lost programs because your disk drive got too hott!)
- Compact Size. The BCD/5.25 takes up a lot less space than the Commodore drive. (And because it’s more efficient…it’s also less expensive.)
- Software Compatible. Runs 1,000’s of programs written for Commodore. Works with almost everything. You name it. Games, Wordprocessors, Spread Sheets, Education packages.
- Easy to read panel indicators tell status of the drive at a glance. Built-in “Power On Diagnostics” included!
- State-of-the-art ceramic read0write heads for long life and trouble free operation.
- TECHNICAL SPECIFICATIONS Model BCD/5.25
|Interface:||Commodore compatible, dual serial port with daisy chain option|
|Number of Tracks:||35|
|Number of Heads:||One|
|Data Encoding Method:||Group Coded Recording (GCR)|
|Net Weight:||3 lbs. 12 oz.|
|Capacity:|| 174,848 bytes per diskette. Total.
168,656 per diskette with Sequeltial Files.
167,132 bytes per diskette with Relative Files.
|Buffer Memory:||2048 bytes|
|Track Density:||48 Tracks per inch.|
|Sectors per Side:||17 to 21|
|Bytes per Sector:||256|
|Blocks per Side:||683|
|Internal Write Protection:||Yes|
|Power On Diagnostics:||Yes|
|Power Consumption:||15 Watts (Typical)|
|Power Supply:|| External – 16 VAC 0.8 Amps
9 VAC 1.5 Amps
|Power Requirements:||120 VAC, 60Hz.|
|Dimensions:||3.0″ x 6.75″ x 10.6″|
|Reliability:||Mean Time Between Failure (MTBF) 10,000 Power-on hours|
|Media Requirements||Industry Standard (ANSI) 5 1/4″ diskettes; soft sectored|
|Warranty:||One year. Parts and Labor|
|Compatible Computers:||Commodore 64, Commodore 128, SX64, Plus 4, C16, and VIC 20|
The label on the front panel says “BLUE CHIP 5.25 DISK DRIVE”. Surprisingly, the lever opens to the left.
On the back, there is a power switch, a proprietary power connector and two Serial connectors.
The power supply (Model No. 108-138) outputs 16V and 9V. It is possible mod the drive to work with a 1541-II power supply (12V and 5V), though.
The board contains
* UC7: 2 KB SRAM (SRM2016C)
* UC8: 16 KB EPROM (“COPYRIGHT 1985 / BLUE CHIP ELECTRONICS, INC. / ALL RIGHTS RESERVED”)
* UD1/UD2: Two 6522 VIAs by UMC
* UD3: A 6502 CPU marked “N 3065”, with a date code of 8622.
It is unknown who made this 6502, I’ve never seen one with these markings.
These are the mechanics, from the top…
…and from the bottom.