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1541

[Picture of 1541, 11k JPEG] Pic. 1: original "brick"

Technical detailsoHistory - Documentation

Description

When the C64 came out (which was nearly named VC30), Commodore introduced the 'new' floppy drive 1541 for almost US$ 600 [1], which was actually exactly the same as the 1540, except it was slowed down a bit, since the C64 was a little bit slower on account of its higher screen resolution which took more processor time so that there was less time left for serial data transfers. As opposed to the UK [2], the 1541 was a big success and slowly replaced the datassettes which were widely used at that time.
All 154x drives are much faster than a datassette, but still they are really slow compared to the transfer rate you could achieve theoretically (which is about 30kB/sec(?)). This snail-like behaviour gave cause to the creation of several floppy speeders, for example the TurboTrans, which can speed up the floppy by up to 200 times. If you want to speed your floppy for copying disks without too much effort, you should build a parallel cable.

Notes:

History

1. The original

[Picture of old 1541 PCB, 27k JPEG] As stated before, the 1541 is actually a slightly modified 1540. Besides that, its PCB has only 3/4 the length of the 1540's PCB and the case color has been adapted to the C64's color from white to brown (pic. 1). A remarkable 'feature' was the calibration method of the 1541 before formatting, which involved the head bumping against the drive's axis. As you might imagine, this method is not quite gentle and led to frequent misalignments of the head. This was changed with the 1541c.

2. The new 1541

[Picture of new 1541 mechanics, 18k JPEG] On the Hannover mass in 1984, Commodore presented a new model of the 1541, which was officially released in early 1985 [3]. The new model did not contain the Alps mechanics with the push-down type lever anymore, but a PC-like turn-down type made by Newtronics. The PCB has been reworked, too. CPU, VIAs, controller chip, and both ROMs were socketed, at least at that time.

3. The 1541c

In 1986, on the Sommer CES in Chicago [4], Commodore presented the 1541c, which was a modified 1541 in a white case to match the C64c's color and with an additional light barrier for track 0 detection.
Alas, this light barrier (or the modified ROM, to be precise) caused slight incompatibilities, and above that, it occupied a bit of the otherwise unused second 8 bit port of one of the VIAs which is used by all parallel speeders. Note that some drives do not have the light barrier built in and some drives have it built in, but not activated.

4. The 1541-II

[Picture of 1541-II, 8k JPEG] The successor of the 1541c was the 1541-II, which was introduced in February 1988 [5]. It which came with an external power supply (which was builtin in the old 1541(c) and caused many problems like read errors due to the heat spreaded by the transformer and the two voltage regulators) and finally two externally accessible device address switches. Due to the completely new mechanics (again by Mitsumi), this drive is about 10% faster than its predecessors.
I should note that this drive is slightly incompatible to the original 1541, since its DOS 2.6 differs somewhat from the original DOS 2.6 found in the original 1541 [5].

Documents

[1] COMPUTE!'s Gazette, Issue 32, Feb. 1986, Beyond the 1541 from Sami Rautiainen's web site
[2] At least that is what I've heard. Please mail me if you can confirm that.
[3] 64'er 3/85, p.14, Neu: stabileres 1541-Laufwerk
[4] RUN 8/86, p.6, Summer CES in Chicago
[5] 64'er 11/88, p.11, 1541, die Dritte

Updated: May 19th, 1998
Created: January 30th, 1997
Status : NOT VERIFIED!
Site copyright © 1997 by Marc-Jano Knopp
This document is part of MJK's Commodore 64 & LCD Page
Brought back to life by Peter Schepers, Dec 10, 2005 because I really liked this site!