Talk:Commodore 1541
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[edit] Better photo needed
This article is in dire need of a better, in focus photo. I may still have a (VIC-20 off-white color) old model in the attic collection, along with the latch and flip door beiges, so I'll try to take a couple photos or unified "stack" photo soon. -- Todd Vierling 03:46, 17 Jun 2005 (UTC)
- Or, if I beat you to it, I'll do it. :-) --Wernher 15:56, 30 November 2005 (UTC)
[edit] Confirmation needed
I just wrote the following in the section on The serial interface: To ensure a ready supply of inexpensive cabling for its home computer peripherals, Commodore chose standard DIN connectors for the serial interface. I'm quite sure I read this sometime, somewhere, but I'll need to check it again. I think the decision was made when they developed the VIC-20. If someone knows more about this, feel free to comment. --Wernher 15:56, 30 November 2005 (UTC)
-- I believe this is covered in the first chapter of COMPUTE's First Book of VIC. --CurtisP 17:09, 24 November 2006 (UTC)
- I can still recall cracking open the case and soldering points on the circuit board to change drive letters in order to add more than one drive to a system.
- What drive letters ? You mean drive number, right ?
[edit] Locking mechanisms
Description of Image:Commodore64 fdd1541 front.jpg, emphasis mine
- Front view of the most common version of the Commodore 1541 disk drive, with open disk slot. This version uses a Newtronics drive mechanism, and the rotating lever is used to hold the disk in place. Note that the small toggle switch in the lower right corner is an aftermarket addition.
Description of Image:Commodore 1541-II.jpg, emphasis mine:
- Commodore 1541-II, the second of two upgraded versions of the CBM 1541 (the first upgrade was the 1541C). The 1541-II has the more modern 'radial handle' locking mechanism.
What is the difference between a radial handle and a rotating lever? boffy_b 23:13, 22 August 2006 (UTC)
[edit] 1571 from nowhere?
The followin paragraph starts talking about the 1571-drive, but no introduction to this drive has been made in the text.. "For compatibility and ease of implementation, the 1571's Double Sided format of one logical disk side with 70 tracks later was created by putting together the 35 physical tracks on each of the physical sides rather than using two times 40 (or e.g. 38) tracks, even though there were no more quality problems with the mechanisms of those drives. The 1571 CP/M format, however, uses the full 360 KB avaiable on that two R/W head drive."
[edit] Slow Bit-Banged Serial vs Fast Shift Register Serial
The second paragraph under the heading The serial computer interface reads:
Because a Commodore engineer at the production site took out two traces from the final drawing of the C64's motherboard, thinking they were redundant, the disk drive transferred data at a tenth of the speed it had initially been designed to handle (see "On The Edge, the rise and fall of Commodore" by Brian Bagnall, for more details).
I believe this is incorrect. The Vic-20 also suffers from the slow speed of the serial bus. I remember reading this is due to the 650X processor having to do manual bit-banging of the serial interface to read out a byte. The VIA chip has a hardware shift register which was originally supposed to be used which would have been much faster as the CPU would be free to do other things until the VIA had read in a full byte but unfortunately there was a bug in the silicon which prevented it from working properly. The VIA chip was also used in the Commodore PET computers for sound generation and the bug in these machines meant sound needed to be turned off (disable the shift register) otherwise I/O operations (on a different parallel interface) would glitch. --24.161.65.18 01:39, 26 September 2006 (UTC)
- Yes. The definitive reference is the IEEE Spectrum article (Commodore 64 should have a link to it). It was a deliberate design decision (in retrospect a poor one) to try to maintain compatibility with the 1540. (In fact, though, it wasn't compatible with the 1540!) Mirror Vax 06:29, 26 September 2006 (UTC)
[edit] Head misalignment: source needed
The following paragraph needs a published source before it can be added to the article. The fix was described to me by a repair technician in the mid-1980s. Then I used it to repair my own 1541 when it finally would not hold its alignment. The fix worked perfectly, so I know the paragraph is factual, but I don't know if it was ever published.
Although a technician could realign the head, the head drive capstan was held to its motor shaft by a swage fitting that could loosen over time, eventually making realignment futile. Future misalignments could be virtually eliminated by drilling a hole diagonally into the top of the capstan and through the motor shaft, and then driving a snug-fitting pin into the hole.
I feel that this information reveals an important underlying cause for the issue, which users tended to blame entirely on copy protection.
Mwbrooks 00:03, 2 December 2006 (UTC)
