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ScuzzBlog: Diaries February 2020

Entry 5th February 2020: Post 01: Commodore - 5'n'a quarter - Floppy Drives.

Commodore - 5'n'a quarter - Floppy Drives.

I have to say I find the range of 5.25" floppy disk drives for
the Commodore low cost machines as fascinating. Although they were
targeted first at the VIC-20 they share very much their origins in
the earlier Commodore PET range. For all these devices are smart
devices with their own processor, memory and own disk operating
system. Further they use a serial derivative IEEE-48 interface
with standard DIN connectors.

The first in the range was the 1540. When the VIC-20 was released
in 1981 it had no floppy drive. Very quickly Commodore released
the VIC-1540 the following year. Please note that the German
equivalent for the drives has the VC prefix and not VIC. This
drive although relatively cheap in terms of manufacture was
surprisingly quick.

That same year the C64 was released, though had a problem with
the timing on the 1540. In truth they were just not compatible.
And so the 1541 was born. If you look at the label to the rear of
the beige case 1541 you will see stickers with and without VIC.
The original VIC-1541 was the off white to suit the VIC-20.

The 1541 is basically the 1540 but with a ROM upgrade. Sadly the
1541 is a slow floppy drive. Single sided with capacity 170kb.
Some interesting facts about the 1541 is the way it reads the disks
from the centre directory track of the disk; writes the track
number to each track on the disk making tracking easier; and
has more tracks to the outer part of the disk than the inner
15 and 21 respectively. You will note that there is hardly any
banging of the drive reader as the drive does not retract the
head each time it needs to find data on the drive. Note that
the 1541 does not support subdirectories. To list the contents
of the drive you use the "$" symbol as the loaded file and the
names are listed only in the order they were written.

Because of the almost stand-alone nature of these drives many had
their chips altered and upgraded to benefit certain applications
like say GEOS, JIFFY/DOS and Dolphin DOS. The units were adapted
in all kinds of ways. One of mine has a switch on the front.

The updated drive to the 1540 was the 1570 which was introduced
to provide faster seek time on the C128 range of machines. This
was then replace by the 1571. The drives offered MFM capability
for use with the CP/M operating system. The 1571 styling very
much compliments the C128 range of computers. Although the 1571
was a double sided machine due to the twin heads, it could not
read the two sides of a disk formatted under the earlier drives.

A later version of the 1541 was introduced to match the styling
of the 1571 and called the 1541-II. This drive removed the power
from the main unit and provided its own special brick. As ever
Commodore introduced yet another power supply connector.
Finding one of these is a pain.

The final version in the series is the 1581 which is a 3.5" disk
drive for the C64.

There was one other drive in the range though due its unique
cartridge style connector was only really suitable for the PLUS4
and that was the 1551. Consequently this was not a Serial Drive.

Serial Drives were:

    Commodore VIC-1540
    Commodore VC-1540
    Commodore VIC-1541
    Commodore VC-1541
    Commodore 1541-II
    Commodore 1541C
    Commodore 1570
    Commodore 1571
    Commodore 1581

Sadly I could never source a 1540 so if you have a spare one kicking
about then feel free to donate to the collection.

One last point and one which has always puzzled me and that is why
the 1541 has both a pull down latch and a rotating style closing
latch to the disk door. I find the pull down version a pain as it
is as likely to spring back up if not closed properly. These drives
also had a safety card for travelling and you were supposed to park
the drive before moving about.

Anyhoo... today's little adventure was primarily to test the five
drives I have linked to the old 'BREAD BIN' C64. One of the areas
of fatigue on these drives is the top left hand corner. One of my
1570 machines is cracked there.

I also tested my other drives on my C64 and VIC-20 set-ups. I
have four machines permanently set up for use with the VIC-20
and C64 range of machines. I can also swap out computers at the
drop of a hat if necessary.

If you ever plan on sending one of these through the post then
pack with generous soft bubble wrap and sturdy cardboard. I
had two 1551 drives literally smashed by the posts office as
heavy parcels were no doubt placed on top of the drive and
crushed them. In the end I went and picked a drive up. Safer.

Commodore - 5 'n' a quarter - Floppy Drives.

All that I have'ish

As ever I do have numbers of drives of the same type.

SFD-1001 SFD-1001 SFD-1001 SFD-1001

SFD-1001 SFD-1001

Commodore SFD-1001

VIC1541 VIC1541 VIC1541 VIC1541

Commodore VIC 1541

1541 1541 1541 1541

Commodore 1541

1541 1541 1541 1541

Commodore 1541 ( new version )

1541 1541 1541 floppy drive

Commodore 1541-II

floppy drive 1551 1551 1551

1551 1551 1551 1551

Commodore 1551

1570 1570 1570 1570

1570 1570
2nd unit arrived July 2005 ( three in collection )

Commodore 1570

floppy floppy floppy floppy

Commodore 1571

1581 1581 1581 1581

Commodore 1581

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Last updated 6th February 2020

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