exxos's Atari, Amiga & retro forum

I wrote a small test program that distinguishes between the two main FDC versions manufactured by WD, the WD1772-00 and the WD1772-02. There is another 1772 chip manufactured by VLSI and labeled as VL1772-02PC. Seems that the VLSI chip is based on the 1772-02. I actually suspect that it uses the same mask, but I'm not 100% sure.

Specially if you have a VLSI chip, please run the test provided here and report the result. The main test is named WHICHFDC.TOS. The archive also includes an alternate test (DETFDC2.TOS), but it shouldn't be needed in most cases. It is expected that the program will identify the VLSI chip as a 1772-02. If it doesn't, please try the alternate test. There is no need to run the alternate test if the program detects the FDC version correctly. Which in the case of a VLSI FDC, it should be detected as 1772-02.

Also, if possible, please try to run the tests from floppy (floppy emulator like Gotek is perfectly fine) without any device connected to the ACSI port. In most cases it should run fine from a hard disk anyway. So as long as the test shows the expected result from hard disk, that is just fine.

Please also let us know the details of the computer you are using for the test. Most interesting is computer type (ST/STE/Mega) and DMA chip.

Please note that the test doesn't attempt to identify the Ajax.

No one with a VLSI VL1772 FDC to run the test? I'm specially interested if somebody happen to have a VL1772 on an STE.

@exxos might know better, but I suspect the VLSI VL1772 is not that uncommon on later computers.

Thanks,

ijor wrote: 11 Mar 2025 12:46 No one with a VLSI VL1772 FDC to run the test? I'm specially interested if somebody happen to have a VL1772 on an STE.
@exxos might know better, but I suspect the VLSI VL1772 is not that uncommon on later computers.

I don't recall offhand seeing any VL in STEs, but I don't have that many STEs and can't say I ever really took notice. I've had 100's of STF/M boards, I have seen VL a lot. I likely have some somewhere, but I don't have time or space to setup another machine to test.

I'm getting over a bad cold currently which has thrown me back with everything as well. Been busy the past couple weeks with fibre internet install (still not finished!!) and server move etc.. just not enough hours in the day..

EDIT:

Are you also aware microchip made the WD1772...

exxos wrote: 11 Mar 2025 12:54 Are you also aware microchip made the WD1772...

No, I had no idea. I suppose you don't have any picture. Let alone a chip :)

ijor wrote: 11 Mar 2025 18:08 No, I had no idea. I suppose you don't have any picture. Let alone a chip :)

I've got 100s of brand new ones *somewhere* :lol: Will add it to my to.do.list...

These are what I have. My supplier said they were microchip.. But I'm not so sure now as it's not the normal logo.. could just be an old logo I suppose..

exxos wrote: 11 Mar 2025 22:06 These are what I have. My supplier said they were microchip.. But I'm not so sure now as it's not the normal logo.. could just be an old logo I suppose..

I don't think this is Microchip. It seems it is just a later WDC logo, at least according to Wikipedia. In anycase it has the WDC initials below the logo. Thanks a lot for the picture!

Interesting, that is a very late WD1772 chip, dated '94 after the Falcon was already released.

I'll ask my supplier tomorrow why they said microchip.. They only sell parts which have a paper trail back to the manufacturer..So something doesn't add up....

exxos wrote: 11 Mar 2025 23:33 I'll ask my supplier tomorrow why they said microchip.. They only sell parts which have a paper trail back to the manufacturer..So something doesn't add up....

It is possible that is related to some acquisition made by Microchip ... yes, it seems so.

WD sold its chip business a few years later to concentrate exclusively on hard disks. I don't find the quote right now. But I remember reading that WD sold, at least their FDC portfolio, to SMSC. Eventually SMSC was aquired by Microchip.

Okay, I ran the test on my 3 machines:

Mega STe - Ajax chip - "Detected FDC 1772-02"

-------------------------------------------------------

STacy - Ajax chip - "Detected FDC 1772-02"

Note that I could not run this in Pak 68/3 mode.
The program crashed with 2 bombs. Disabling
the Pak accelerator and dropping back to plain
TOS v1.04 @8mhz worked fine though.

Normally, a STacy would not have an Ajax chip
but I do because I'm using the 1.44 HD floppy
modification from Exxos.

--------------------------------------------------------

Mega ST4 - VLSI chip - "Detected FDC 1772-02"

VLSI Info:

88458V R7043
VL 1772-02PC

DMA Info:

C025913-38
PH23-030
8G2 04

BTW, when running the software on the Mega ST4,
you could hear the floppy drive. It didn't do that on
the other 2 machines.

I'm attaching a picture (low quality) of those 2 chips
on my Mega ST4 so you can see it yourself, in case I
misread any of those figures.

Hope this helps. :)