Jump to content
SoulBuster

XF551 3.5 Mod

Recommended Posts

Finished the conversion of my XF551 from 5 1/4 to a 3 1/2 inch drive.

I took me awhile to find the answers on how this upgrade was done (I even had to guess at some of it). I wanted these instructions to be at the top of a thread instead of buried in the middle of another, just in case someone else wanted to create one of these "novelty" items.

I CANNOT STRESS THIS ENOUGH!!! THE XF551 PCB IS A SINGLE SIDED PCB AND IS VERY FRAGILE. OVERHEATING WILL CAUSE TRACES TO BREAK.

If you are not handy with soldering tools, leave it to professionals. These instructions are written for professionals. If anything in here confuses you, stop and get help.

Parts Needed

1 28 pin wide socket (Only if U6 does not have a socket already in it)

1 longer floppy cable with IDC connector (optional additional card edge connector for the purpose of returning to the original mechanism or dual mechs, not covered here)

1 Molex to 4 pin floppy power adapter

1 2764 eprom programmed with the new XF551 rom (lots of places to download).

1 5 1/4 to 3 1/2 inch drive mounting adapter.

Tools

Soldering Iron (30 watts max, I use a 15/30 watt)

Desoldering Item (desoldering plunger, desoldering iron (30 watts max, my preference) or desoldering wick)

Needle nose pliers

Phillips screwdriver

Precision flat head screwdriver

IC Remover

I will not go through the mundane steps of taking apart the XF551 as it is pretty self evident, take all the screws out. There is one screw that is the exception. There are 4 screws to remove the PCB. 3 are easily visible. The 4th is located under the heat dissipator and there is a hole provided to reach it. Getting it out is easy enough, but putting it back, I used a magenetic screwdriver.

First look at U6 on the PCB. I imagine there are 4 possibilities.

1. It is empty. Your drive is using the "internal" OS. You will need to desolder the holes of U6 then solder in a 28 pin wide socket.

2. There is an empty 28 pin socket. Your drive is using the "internal" OS.

3. There is a 28 pin IC soldered to the PCB. Your drive uses the "external" OS. You will need to desolder the IC in U6 and then solder in a 28 pin wide socket.

4. There is a 28 pin IC mounted in a socket. Your drive uses the "external" OS. You only need to remove the IC from the socket.

In all cases, your programmed 2764 goes in this socket and will be used as an "external" OS.

Next look near the 40 pin IC. There are two jumpers (a wire over the PCB) labeled S3 and S4. These decide whether you are using an "internal" OS (S4 jumped, S3 empty) or an "external" OS (S3 jumped, S4 empty). With the upgrade being an "external" OS, S3 needs to be jumped and S4 needs to be empty. If S4 is jumped, you can remove it and use it to jump S3. To remove with the best possible results, use your precision flat head screw driver to straighten each end of the jumper pins while heating it with your soldering iron. Let it cool completely, then use the desoldering tool of your choice and remove. Resolder it in S3.

Replace ribbon cable.

A. Using the precision screwdriver, unlock each side of the plastic crossbar of the IDC connector that is soldered onto the XF551 PCB. Do this next to the PCB, it cannot be done from the top.

B. With the crossbar removed, take note of where pin one is by the colored line of the cable. Use the precision screwdriver to carefully lift the ribbon cable from the IDC connector starting at one end and slowly moving to the other.

C. When attaching the new ribbon cable, I do not reccomend using a squeeze method (vise) using the crossbar. The XF551 PCB is so fragile, I would not be surprised to see it break if this method were used. Line the new longer cable up with pin one (you took note of this above). I used a pair of needle nose pliers to gently push the ribbon cable itself onto the connector, layin each side of the pliers on either side of the pins to give me even pressure. You must have patience when doing this. Then I placed the crossbar on as a cap.

Mount the completed the PCB in to the case (rememberthe screw I mentioned above?).

The XF551 drive requires the drive mechanism to be jumped as drive 0. All modern 3 1/2 inch PC drives are jumped as drive 1 permanently, but usually have a way to solder a wire to jumper it as drive 0. You will need to consult the manufactuer's specs and make it a drive 0 mech.

Mount the 3 1/2 inch drive in your mounting adapter. Remove the XF551 mechanism mounting rails from the 5 1/4 inch drive and attach them to the 3 1/2 inch mounting adapter. Mount this assembly to the drive case. Attach the new ribbon cable and the power adapter to the drive.

Plug in your computer and test with Sparta DOS.

Test Successful, reassemble case.

100_2117_zpsbd97a1c8.jpg 02_zps1e9d5b8b.jpg03_zps2a924d86.jpg100_2125_zps08c46c8c.jpg100_2128_zps9a6616ad.jpg100_2127_zps518d7e72.jpg 100_2123_zps44045e0a.jpg

  • Like 6

Share this post


Link to post
Share on other sites

It only takes about an hour to an hour 1/2, once you have all the information. Took me 5 days to get all the information together and make my guesses.

  • Like 1

Share this post


Link to post
Share on other sites

What were your original source(s) for these docs? I'm curious about some of the steps/possibilities listed that I've not seen required before on US model pcb's. Not saying they don't exist, but seeing the posters/locations might put some context to those instructions (e.g. European models?).

 

BTW, I've found it much easier to extend the ribbon cable (when required) than to do a cable replacement.

 

-Larry

Share this post


Link to post
Share on other sites

Just had a look at my 3.5" modded XF... seems I replaced the original ribbon with one which has both 5.25 and 3.5 inch floppy connectors.

 

Must admit I've lost track of which is the best 80 track ROM for use with this mod.

Share this post


Link to post
Share on other sites

What were your original source(s) for these docs? I'm curious about some of the steps/possibilities listed that I've not seen required before on US model pcb's. Not saying they don't exist, but seeing the posters/locations might put some context to those instructions (e.g. European models?).

 

BTW, I've found it much easier to extend the ribbon cable (when required) than to do a cable replacement.

 

-Larry

 

I got a lot of the information I needed to complete my drive from the dual drive upgrade (I had to back out everything regarding a dual drive to make it a single drive upgrade.)

 

The only other documentation I found was Bob Wooley's article in Antic (which is included with the roms). It explains how to modify the roms code to be able to use a 3.5 drive, but does not explain how to install everything into the drive case.

 

The rest was my own conclusions on how to get my drive upgraded and some suppositions for other OS rom configuration possibilities.

 

Just had a look at my 3.5" modded XF... seems I replaced the original ribbon with one which has both 5.25 and 3.5 inch floppy connectors.

 

Must admit I've lost track of which is the best 80 track ROM for use with this mod.

 

I used the Hyper XF Roms.

 

You can also use this method to get a more stable OS for the 5 1/4 in mech. The only parts you need are the U6 and S3/S4 parts of the instructions! The zip files come with a rom for the 3 1/2 inch upgrade as well as a modified rom for 5 1/4 inch mech. On of my other drives will get the 5 1/4 inch upgrade.

 

I have done some testing and found that you can set Sparta DOS to DSDD and tracks to 77 (8 inch drive) and you can format a 1.44 disk, with the hole covered (you know 720k) to just over a meg. I cannot vouch for stability of the data written to it, but you can fill it, for how long who knows, just an FYI here.

Edited by SoulBuster

Share this post


Link to post
Share on other sites

I got a lot of the information I needed to complete my drive from the dual drive upgrade (I had to back out everything regarding a dual drive to make it a single drive upgrade.)

 

The only other documentation I found was Bob Wooley's article in Antic (which is included with the roms). It explains how to modify the roms code to be able to use a 3.5 drive, but does not explain how to install everything into the drive case.

 

The rest was my own conclusions on how to get my drive upgraded and some suppositions for other OS rom configuration possibilities.

 

 

 

I used the Hyper XF Roms.

 

You can also use this method to get a more stable OS for the 5 1/4 in mech. The only parts you need are the U6 and S3/S4 parts of the instructions! The zip files come with a rom for the 3 1/2 inch upgrade as well as a modified rom for 5 1/4 inch mech. On of my other drives will get the 5 1/4 inch upgrade.

 

I have done some testing and found that you can set Sparta DOS to DSDD and tracks to 77 (8 inch drive) and you can format a 1.44 disk, with the hole covered (you know 720k) to just over a meg. I cannot vouch for stability of the data written to it, but you can fill it, for how long who knows, just an FYI here.

From what I understand it isn't recommended to use 1.44MB disks with the High-density sensor disabled, I believe doing so reduces the field strength of the heads and HD media uses the higher field strength to make the data reliable over the long term.

  • Like 1

Share this post


Link to post
Share on other sites

15 years ago, I think, I tried to repair some XF551 boards.

Some had defective IC's and other had broken traces.

 

Eventually I managed to repair two. And a common problem on these drives is that the traces also break easily when you 'jiggle' the SIO connector too much. So be carefull with those.

Maybe its even better, to leave a SIO cable connected.

 

I transformed one of the XF551's into a 3.5" drive. I bought the HyperXF ROM at ABBUC JHV from S.Dorndorff.

 

Anyway, I was glad I found a 3.5" drive with a 5.25" adapter attached to it.

post-29177-0-50773700-1356558839_thumb.jpg

post-29177-0-99800400-1356558893_thumb.jpg

  • Like 2

Share this post


Link to post
Share on other sites

I don't have immediate plans to do this, but I might, one day in the future. I really appreciate your taking the time to document what you did, and share it.

 

Big thumbs-up, to you! :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

Share this post


Link to post
Share on other sites

Thanks, there really wasn't any instructions on the internet on how to do this. I just figured it needed to be put out there somewhere.

Share this post


Link to post
Share on other sites

Where can I purchase the HYPER XF ROM

I am including an expired listing from ebay, the seller doesn't have a current listing but might put up a new one if you contact him.

https://www.ebay.com/itm/Atari-XF551-Disk-Drive-Firmware-upgrade-ROM-chip-XE-XL-/132892569572?hash=item1ef103afe4&nma=true&si=qTuuwIbghnzmRZLlX0B0te8NUh8%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

 

If you have the ability to burn your own EPROMs the files are available here.

  • Like 1

Share this post


Link to post
Share on other sites

15 years ago, I think, I tried to repair some XF551 boards.

Some had defective IC's and other had broken traces.

 

Eventually I managed to repair two. And a common problem on these drives is that the traces also break easily when you 'jiggle' the SIO connector too much. So be carefull with those.

Maybe its even better, to leave a SIO cable connected.

 

I transformed one of the XF551's into a 3.5" drive. I bought the HyperXF ROM at ABBUC JHV from S.Dorndorff.

 

Anyway, I was glad I found a 3.5" drive with a 5.25" adapter attached to it.

 

Please DUMP the HyperXF ROM and post it here. Much appreciated.

 

:)

Share this post


Link to post
Share on other sites

wasn't there pal and ntsc versions of the roms?? also there was postings about this on AA about the partitions and other functions, someone involved with the project discussed it's completeness and how to do things as many had difficulties.. he cleared things up...

Share this post


Link to post
Share on other sites

Both versions(5.25"/3.5") are available at the bottom of the following web-page.

http://blog.3b2.sk/igi/post/Hyper2b-XF-10-MANUAL.aspx

8KB ROM files, so should be just a 2x64 EPROM. If that's all it is I really should just try this in my own XF551 that's been mostly idle, as even with the original 5.25 mech this sounds cool.

 

For those that don't have a programmer, I can program these and mail them at my cost (usually less than $5 all in worldwide) just PM me.

  • Like 1

Share this post


Link to post
Share on other sites

I remember there are two different firmwares for xf551 3.5... Which are the differences? pros and cons?

Share this post


Link to post
Share on other sites

Pretty good thread here on the various roms and mods for the XF551.....

 

http://atariage.com/forums/topic/108472-xf551-oses/?hl=%2Bxf551

 

I just went through the ROM's attached in that thread, and compared the CRC32's:

  • Atari XF551 360K PAL 0E117428
  • Atari XF551 360K PAL 38B97AE3
  • Bob Woolley 360K 38B97AE3
  • Bob Woolley 720K 0E117428

We have a dupe on 2 of them, so need to confirm which is who's...

Share this post


Link to post
Share on other sites

I am including an expired listing from ebay, the seller doesn't have a current listing but might put up a new one if you contact him.

https://www.ebay.com/itm/Atari-XF551-Disk-Drive-Firmware-upgrade-ROM-chip-XE-XL-/132892569572?hash=item1ef103afe4&nma=true&si=qTuuwIbghnzmRZLlX0B0te8NUh8%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

 

If you have the ability to burn your own EPROMs the files are available here.

Sorry, about the stupid post. I didn't see the link.

Share this post


Link to post
Share on other sites

I just went through the ROM's attached in that thread, and compared the CRC32's:

 

  • Atari XF551 360K PAL 0E117428
  • Atari XF551 360K PAL 38B97AE3
  • Bob Woolley 360K 38B97AE3
  • Bob Woolley 720K 0E117428
We have a dupe on 2 of them, so need to confirm which is who's...
What ROM is in this thread/zip: http://atariage.com/forums/topic/115775-xf551-pal/?p=1398344

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...