XF551 with 3.5 disk drive.

[Senior Tech]

    I have 4 or 5 XF551's with 3.5 DS/DD disk drives in them.  Mostly TEAC FD235HF model drives.  They are unmodified, still patched for DS1.  HYPROM B Ucode.  The only modification is on the J4 ribbon cable  connector.  The file going to pin 10 (DS0) has been cut off.  A wire has been added from pin 12 (DS1) to the foil cut off of pin 10.  With the HYPROM B Ucode they work beautifully with SDX , format to 2880 sectors, Ultraspeed.

   Question:  Who came up with this Mod.?  I've never seen it mentioned anywhere.  The ones I have had bad soldering on the SIO interfaces and/or bad power connectors.

   I have 3 XF551's without a good Disk Drive.  Been thinking of modifying one with a switch on J4 connector pin 10 and 12.  Switch between 5.25 and 3.5 disks for testing.  I understand that I would also have to swap the PROM, HYPROM A or HYPROM B.

[cx2k]

If I remember, I think Bob Wooley published upgrade info years ago for this.

 

John

 

[+CharlieChaplin]

My guess... HypROM A/B = Hyper-XF OS ROM version A (5,25") or B (3,5") by Stefan D. Dorndorf from Germany.

 

He also made QMEG-OS, DOS II+D , XDOS (V 2.43), Hugojagd XL (first appeared on the A8, the 2600 cart version is now available at the AA store) and various other things for the A8 (e.g. Star Raiders with fast explosions and score ).

 

http://atariki.krap.pl/index.php/Stefan_Dorndorf

 

If you search for Hyper-XF OS here in the AA forum you should get several hits and here you should find a Hyper-XF manual.

[+bob1200xl]

I did the mod a long time ago. There should be threads on it all over AA and the net.

 

I have enough XF551s and parts that I just do individual drives and power on the one I want.

 

Bob

[Senior Tech]

16 minutes ago, bob1200xl said:

I did the mod a long time ago. There should be threads on it all over AA and the net.

 

I have enough XF551s and parts that I just do individual drives and power on the one I want.

 

Bob

Then are you the one that came up with this mod?  I haven't seen anything, anywhere about making this mod to the cable connector. pin 10 to pin 12.  I always look for simple mods like this and try to record them.  I haven't searched for it here - yet.

[+bob1200xl]

Pin 10 is motor control and pin 12 is DS0, it seems. A regular FDD is jumpered for DS1, while the XF551 is set to DS0. Are you sure that it is pin 10 and 12 and not 12 and 14?

 

Bob

 

[Senior Tech]

9 hours ago, bob1200xl said:

Pin 10 is motor control and pin 12 is DS0, it seems. A regular FDD is jumpered for DS1, while the XF551 is set to DS0. Are you sure that it is pin 10 and 12 and not 12 and 14?

 

Bob

 

I just checked the 551 schematic.  pin 10, DS0; pin 12, DS1.  MO is pin16.  Pin 14 is DS2, not connected.

[Mathy]

Hello Senior Tech

 

HYPROM probably means HyperXF ROM, which, as Andreas (CC) already wrote, was developed by Stefan Dorndorf.  He should be around here somewhere at the Fujiama.

 

Sincerely

 

Mathy

 

[+Nezgar]

The physical drive modification

22 hours ago, Senior Tech said:

Who came up with this Mod.?

The modifications were first described by Bob Woolley in the January, 1989 issue of Atari Interface Magazine "Inside the XF551 Disk Drive" page 7 (page 8 in the PDF):

https://archive.org/details/atari_interface_jan89/page/n7/mode/2up

 

Here's a text version:

https://www.atariarchives.org/cfn/05/07/0063.php

[Senior Tech]

Yes, I just read them.  But no where does it say to cut the foil off the J4 (Ribbon cable) connector, pin 10 (S0) and wire the foil to pin 12(S1).  I'm trying to find out who built these drives in the first place.  I have 2 (working) and I just worked on and repaired 4 others.  They all had some other code in them, I won't say whose, and I changed them all to the Hyper XF ROM, HYPROM B on the label.

[Senior Tech]

6 hours ago, Mathy said:

Hello Senior Tech

 

HYPROM probably means HyperXF ROM, which, as Andreas (CC) already wrote, was developed by Stefan Dorndorf.  He should be around here somewhere at the Fujiama.

 

Sincerely

 

Mathy

 

Yes it is.  But HYPROMA or HYPROMB is what the file name is and is on the chip label.  So, I try to keep it simple.

[cwilbar]

Sounds to me like the 3.5" drive put in the XF551 is a PC drive without a selectable ID, so hardwired to the second floppy (as the PC cable uses a twist so both drives are jumpered as drive 1, and the twist takes care of routing ds0 from the mainboard to ds1 on the 1st floppy drive (drive A)).

 

I believe that the XF551 requires the drives to be at drive ID 0, so by modifying the DS0 and DS1 signal routing, when the XF selects drive id 0, drive id 1 (the floppy mech) responds.

 

I would probably have do this through the cable itself, or the drive mech itself vs modifying the XF551.  I have a small 'hoard' of 3.5" drives with varying amounts of jumpers to them specifically for old systems where the configuration of the drive needs to be different than what an IBM PC expects.

 

I burned the HyperXF ROMs to try, but haven't gotten around to trying them yet.

 

 

[Peri Noid]

You need to switch the drive to DS0:, otherwise it doesn't work. It's usually a simple thing, just one jumper to be soldered.

[1050]

On 9/16/2021 at 10:38 AM, Senior Tech said:

  Question:  Who came up with this Mod.?  I've never seen it mentioned anywhere. 

I won't take credit for it, but I posted a thread here years ago (2015?) showing how to do it under the ribbon cable jack on the XF551 board. BECAUSE I had 3.5 drives that had no jumpers, they were made to be D1: and this was the only way it was going to work. It involved cutting the trace next to the header of pin 10 underneath the board and jumpering the trace feeding it over to pin 12.  Pin 16 (MO) is connected to pin 10 (DS0) on the XF-551 board as is, just need to block pin 10 and shunt that signal to pin 12 (DS1) which is right next door. I was quite pleased with myself and figured somebody might find it useful themselves. I've tried to find some of those old posts of mine to harvest posted pictures, etc., that have become lost as versions of windows crash on me and I loose stuff that way. But I don't have very good luck finding much.

It would appear that some one did see it and had the same luck I did?

 

Puff did something similar using a small circuit board IIRC that changed things in that region, mid cables on his dual 5.25/3.5 drive that I got to play with for while. It was a confusion at the time, but it made some sense when I ran into my modern 3.5 drives that also needs pin 3 pulled or broken off or the drive won't work if it's used in a PC. And that boondoggle from the days of IBM PS/2, those floppy drives used pin 3 for something I can't even remember.

[Senior Tech]

11 hours ago, 1050 said:

I won't take credit for it, but I posted a thread here years ago (2015?) showing how to do it under the ribbon cable jack on the XF551 board. BECAUSE I had 3.5 drives that had no jumpers, they were made to be D1: and this was the only way it was going to work. It involved cutting the trace next to the header of pin 10 underneath the board and jumpering the trace feeding it over to pin 12.  Pin 16 (MO) is connected to pin 10 (DS0) on the XF-551 board as is, just need to block pin 10 and shunt that signal to pin 12 (DS1) which is right next door. I was quite pleased with myself and figured somebody might find it useful themselves. I've tried to find some of those old posts of mine to harvest posted pictures, etc., that have become lost as versions of windows crash on me and I loose stuff that way. But I don't have very good luck finding much.

It would appear that some one did see it and had the same luck I did?

 

Puff did something similar using a small circuit board IIRC that changed things in that region, mid cables on his dual 5.25/3.5 drive that I got to play with for while. It was a confusion at the time, but it made some sense when I ran into my modern 3.5 drives that also needs pin 3 pulled or broken off or the drive won't work if it's used in a PC. And that boondoggle from the days of IBM PS/2, those floppy drives used pin 3 for something I can't even remember.

    So I guess you're the one.  I have two myself and just repaired 4 others for another person.  Broken traces on the SIO connectors and on Pwr connectors mostly  A good head cleaning, putting in the HYPROM B prom and they work great.

   Yeah, I'm working on 3 of those CSS dual drives.  One has a reversing switch on the DS1 and DS2.  Suppose to swap the floppy drives.   Had to rewire the SIO interfaces and the pwr connectors.  I do have one of them working, switch on the front for CSS mode and 1050 mode.  1050 mode is to format and write to flippies, no need for the index hole.

   Thanks for answering my question;    Senior Tech

[1050]

Not a problem, I was chunking out several single 3.5 drive ones during those days myself, not so much anymore. I got to where to where I would just count on using JB Weld and pop rivets on the SIO jacks because the real reason they fail is weak rivets to hold them on the board properly which quickly grew into JB Weld for the power jack as well because it gets loose too and then the same problem shows up there. My 800XL has the same SIO sockets but it's a double sided board and the rivets are clearly thicker so they have some actual bite when installed. I'm guessing by the time the XF551 came out cheaper inputs were the norm on how Atari corp would float from then on with the results we have to fix constantly.

 

Those CSS dual drives were very popular, and should command a great price if only you can find someone that is willing to sell them.