GandALF, sub for 1541 custom IC MOS 325572-01

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eslapion
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GandALF, sub for 1541 custom IC MOS 325572-01

Post by eslapion » Sun Jul 30, 2017 5:46 am

It is with great pride that I announce you all that in the coming weeks, I will be offering a new product.

GandALF is a replacement module for the MOS 325572-01 custom IC installed in all VIC-1541 and 1541 disk drives that use the mid sized boards (1540050, 250442 and 250446).

The Gate and Array Logic for Floppy is about the only component on the electronics board of the standard 1541 and the later VIC-1541 for which there is no current version or cross reference on modern components list.

Using technology similar to what's used on PLAnkton, me, e5frog (Fredric Blaholtz) and electrical engineer Sylvain Brisebois were able to create a fully functional and perfectly compatible module to replace this IC which is specific to the 1541 series of floppy disk drives and only ever made by MOS or the Commodore Semiconductor Group.

No other company or individual has ever previously offered a compatible or equivalent replacement component.

The price is 20 Euros or 23$US per unit. I am now accepting pre-orders.

Image
This prototype was tested successfully


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Gyro Gearloose
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by Gyro Gearloose » Tue Aug 01, 2017 3:16 am

Very interesting. Do the other drives like the 1541-II, 1571, or SFD-1001, use the same part or something similar?
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by eslapion » Tue Aug 01, 2017 4:20 am

Gyro Gearloose wrote:
Tue Aug 01, 2017 3:16 am
Very interesting. Do the other drives like the 1541-II, 1571, or SFD-1001, use the same part or something similar?
The 1541-II uses a slightly more complex chip to do the same job even if there are great similitudes with the 1541. U10 integrates the functions of the MOS 325572-01 along with a couple more.

The 1571 is a much more complex drive which supports 2 MHz mode as well as MFM formats with the WD1770. U6 is the chip which carries the functions of the 325572-01 along with a bunch of others.

While it was possible to compare the schematics of the old VIC-1540 drive with the schematics of later drives to know exactly what was integrated in the MOS 325572-01, there is virtually nothing to indicate exactly what has been added to the custom encoder/decoder ICs of the 1541-II and 1571.

The SFD-1001 is a whole different ball game altogether.
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by Gyro Gearloose » Wed Aug 02, 2017 12:31 am

Very good, I thought so. I just felt like clarifying that for the benefit of others.

Say... What are the symptoms of a drive that needs a GandALF?
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by eslapion » Wed Aug 02, 2017 3:56 am

Gyro Gearloose wrote:
Wed Aug 02, 2017 12:31 am
Say... What are the symptoms of a drive that needs a GandALF?
Pretty much the same as you would have if the RW head is dead. You'll be able to get a drive status but you can't read the directory or any files at all.

Since the 325572-01 is also responsible for the head movement decode, it's also possible you can read the directory but you'll get errors if you try to load any file.

If the encoder portion of the original IC is faulty then you'll always get errors if you try to format a floppy or save anything.

Most of the time, if this IC has been damaged then it could be because of a faulty 6522.

Sidenote: The first 2 units were sold today to a buyer on Amibay.
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by Gyro Gearloose » Wed Aug 02, 2017 5:23 am

Is there a 1541 diagnosis software that can point in the general direction of a hardware fault?
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by eslapion » Thu Aug 03, 2017 5:04 am

Gyro Gearloose wrote:
Wed Aug 02, 2017 5:23 am
Is there a 1541 diagnosis software that can point in the general direction of a hardware fault?
Usually the diagnostic tools on the test/demo disk of the 1541 can do a pretty good job. If you can simply format a diskette the usual way then you've just tested almost everything on the electronics board of a 1541.

The only thing they can't really check for is a misaligned head but that can be verified with an oscilloscope and a reference disk. Misalignment is something that has strictly nothing to do with a problematic 325572-01.
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by Zippy Zapp » Fri Aug 04, 2017 4:29 pm

Wow! This is really cool. I think I have a 1541 where I had swapped every chip and found that the only one left was this IC, which of course you can't find in the wild usually. The drive symptoms are the same as listed on Ray Carlsen's page:
UC1 325572-01 MOTOR CONTROLLER
When drive powered up, red LED comes on and goes out, but spindle motor does not turn. When LOAD attempted, spindle does not turn, red LED flickers, screen displays "FILE NOT FOUND" and red LED flashes. Can also cause spindle to run when drive not accessed.
I will have to see if I still have that drive hanging around someplace. I may have gave it away.

For mine, No motor as per above except for a split second when you power it off.
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by Gyro Gearloose » Sun Aug 06, 2017 6:39 pm

I was a bit bored going through eBay and I found all these "compatible" floppy drives like the Indus GT and Enhancer 2000. I have no idea what's in them, could they have used the same C= chip too?
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Re: GandALF, sub for 1541 custom IC MOS 325572-01

Post by eslapion » Mon Aug 07, 2017 10:11 pm

Gyro Gearloose wrote:
Sun Aug 06, 2017 6:39 pm
I was a bit bored going through eBay and I found all these "compatible" floppy drives like the Indus GT and Enhancer 2000. I have no idea what's in them, could they have used the same C= chip too?
I couldn't find a pic of the Indus GT's board... that's too sad as I used to own one. The Enhancer 2000, apart from the 4 core large circuits (CPU, 2 VIAs and ROM), has a bunch of discrete logic chips so no use for GandALF there.
Last edited by eslapion on Tue Aug 08, 2017 7:04 am, edited 1 time in total.
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