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XF551 3.5 Mod

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When everything works correctly, can the 3.5 drive be used as drive 1-4 by changing the 551 drive dip switch?

 

Yes.

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Don't flip the 34 wire drive cable. Pin 1 MUST always go to Pin 1.

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I think she was referring to some drive that start with pin 1 on the left as opposed to the right..... I always look at the silk screen and the square pad on the board and look for keyed pins or header to be doubly sure of pin 1 location for connector orientation

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Don't flip the 34 wire drive cable. Pin 1 MUST always go to Pin 1.

 

Pin 1 should go to Pin 1. But where is pin 1? Is it top left, top right, bottom left or bottom right on the drive? On that XF Mixed Part board I orientated the IDE socket a certain way. To connect properly to the drive he is using he may need to flip the cable at the drive end. That's one reason I asked him to list the make and model of drives he is trying to use.

 

The worst that will happen if it's not correct is that the drive motor will run constantly. Happened enough to me in the early PC days when the floppy drive manufacturers wouldn't notch their connectors or indicate pin 1 on the drive and I inadvertently flipped the cable. ;-)

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I have a Sony MFD-11W-41, a TEAC FD-235HG, and a NEC FD1231T. I am hoping that the problem is with my cable. I just ordered an adaptor so I can change from the card edge connector to the female 34 pin connector. I know the current card edge connector is working on my 5.25 drive.

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Based on a non-exhaustive google search here's what I found on these 3 drives

1. Sony MFD-11W-41:
Non-standard floppy drive, does not have standard separate 4-pin power, combines data and power into one connector, needs a Tandy adapter card to have separate data and power connectors. Without that its very doubtful you will get it to work. Not impossible though.

2. TEAC FD-235HG:
Per TEAC this is a drive designed for PC 1/1.6/2MB storage format. I'm not seeing in Teac's dataflyer that it is compatible with 720K. A big question mark here.

3. NEC FD1231T:
Per NEC this is a drive designed for PC 1/1.6/2MB storage format. Again I'm not finding information that it is compatible with 720K. Another big question mark here.

I'm not saying none of these drives will work or can be converted to work, but I'm also not finding any indication that someone has already modified those particular models for use with an 8bit Atari.

For best compatibility you want a floppy drive designed for 720K or at minimum able to read/write 720K. A bonus would be to have it default to write only 720K.

Here's a thread where some compatible drive make and models were discussed and information linked to.

 

XF551 compatible 3.5" drives

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The Sony that I have does have a 4 Pin power cable it also has a slider switch to select d0,d1,d2,d3. It still doesn't work.

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The Sony that I have does have a 4 Pin power cable it also has a slider switch to select d0,d1,d2,d3. It still doesn't work.

 

Are you using a two connector cable or a three connector cable with a twisted patch between the second and third connector? Is it commercial or homemade?

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Can you verify any of these floppy drives currently work in a PC? If they won't work there, they won't work connected to a XF551 board either. :?

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It would be news to me if a 1.44 drive was incapable of 720K mode... (at least in a PC)

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I seem to remember that when floppies were approaching EOL, the OEMs stopped supporting 720K and only ran 1.44. Save a few cents...

 

Bob

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I am using the cable that is original to the PCB with a card edge adapter. The cable works with the 5.25 drives. I am going to cease working on this thing until I find a supposedly compatible drive.

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It would be news to me if a 1.44 drive was incapable of 720K mode... (at least in a PC)

 

 

I seem to remember that when floppies were approaching EOL, the OEMs stopped supporting 720K and only ran 1.44. Save a few cents...

 

Bob

 

You see that dropping of older technology all the time in many industries. Normally in the same format you would expect the manufacturers to provide backward compatibility, it just makes sense to the user. But to the manufacturer it's extra cost in parts, space, programming and support, maybe not a lot per unit, but in the millions it does add up. And when the market begins to dry up everything has to be cheaper and smaller and better to even continue to be produced. A legacy feature in a new device is not enough of a selling point any more to justify.

 

Remember both of the latter two drives were not just normal 1.44MB drives. They were actually latter models when the demand for even higher storage capacity was the only thing selling the floppy drives anyway. Both top out at 1.6 and 2.0 MB

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I am using the cable that is original to the PCB with a card edge adapter. The cable works with the 5.25 drives. I am going to cease working on this thing until I find a supposedly compatible drive.

 

Here's what you should be using. This cable has no twist and has the proper connector already at one end for the drive connection.

 

I would do a fuller search in this forum for other threads dealing with compatible 3.5 drives. There are several and it may give you additional information and drive options.

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All 3.5 are 720K compatible according to this:

 

http://jope.fi/drives/diskettes-jumpers.pdf

 

But it's important to use 720K disks - are you?

They will have only one corner hole that has a

sliding window to make it write protected. It needs

the hole closed in order to be formatted or written

to. Open thru hole here is write protected. 1.44

disks have a sensor hole both left and right side.

 

I have been able to have some success plugging up the

density sensor hole with 1.44 disks, but this is not

an optimum solution at all. It's a hack you can

sometimes get away with. But for long term data

storage one should always use only good quality 720K

floppies.

 

The title of the above pdf is given in line one. It

has searchable results to the extent I've got my own

hardcopy coming via amazon for $5 to my door in three

days. Why I waited so long is a mystery.

 

All three you finally revealed that you are working with

would do. The sony being the easiest it sounds like.

 

Pin 1 on modern drives is easy to spot because pin 3

has been removed and that puts pin 1 in that corner

next to the missing pin.

 

PS/2 (IBM Personal System/2 1987) used pin 3 and since

those days they started removing pin 3 from floppy

drives for compatibility with more modern PC super

I/O chips that will puke if the older drives start

talking to it on pin 3. So they cut them off and then

that doesn't happen no more.

 

It might be the case where even if the red wire is

pin 1 AND you have the card edge adapter to 34 pin

header socket, that it still needs to be flipped over

at the card edge to have pin 1 of the cable get to

pin 1 of the drive. OR the card edge adapter flipped

over - I can't really help you figure out which either.

It's not an unusual thing to have the notch in the

floppy socket on the wrong side too, so much so that

several have two notches top and bottom to work around

that issue. I've seen plenty of 3.5 34 pin headers

with no locating block to allow plugging into drives

that had the wrong IDE socket too.

 

TEAC FD-235HG

https://gekk.info/misc/fd505%20jumper%20setting.pdf

 

 

To use the NEC you will have to work around the lack

of a simple means to make it DS0.

 

https://www.msxinfo.net/2014/05/23/making-a-nec-fd1231h-diskdrive-msx-compatible/

 

Pin 2 and pin 34 have nothing to do with making the

drive respond to DS0 signals so ignore those mods.

And there is a better method than placing a jumper

wire on the surface mount FDC.

 

You need to flip the drive over and cut the jack connector

lead to pin 12 so that signal is not used as an

input any more. At the bend where the brass looking

connector pins take a 90 degree bend into the circuit

board, cut that bend on the sixth lead counting from

the left. I have the same drive here and I'm modding

it for DS0. You can see a small 2 at the left most

pin row of concern and that identifies pin 2. That

row is even numbers only, 2, 4, 6, 8, 10, and 12 is

sixth over. A solder blob between pin 10 and 12

on the other side completes the conversion that

forces this drive to respond to Drive ID 0 as the

XF-551 does it.

 

It it helps, the odd pins are usually all ground on

both 5.25 and 3.5. Most pins on those odd rows will

show continuity with each other when using a DVM

or beeping continuity checker. It's a quick way to

ensure your floppy cable is copacetic all the way to

the drive itself.

 

No harm in taking a break either, I do it all the

time.

 

2MB is the raw unformatted rating, consider it to be

the 1.44 capable and 1MB raw to be 720K. 1.6MB might

be tricky 720K with more tracks than 80 and/or more

sectors per track or both. Toshiba ND-3561GR is

capable of 84 tracks for example and a whopping

1,802,240 free bytes which shows in DOS as 1,760Kb.

Same exact size as win98se CAB files and not a

coincidence either. This is how you make 98se

installation floppies, called DMF format by MS. You

just copy the CAB files from the CD to the floppies

once they are properly numbered as they will be called

for by CAB file name/number when needed during the install.

You need a special program to pull off that DMF

format. FDformat is it. And of course a 9x PC in

boot to DOS mode. And 70 plus odd floppy disks. :)

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Pictures of your 34 pin card edge converter? No, they

don't make those very commonly and I've never used

one in favor of a new cable from the XF-551 board.

But I'm assuming they can go with some struggle two

ways onto the drive and then the card edge could be

used with the 5.25 connector in two ways as well

if it doesn't have the slot excluder used on some of

those connectors. Again not a standard issue, some

have one set up correctly (or not) and others don't

have one at all. I've seen both ways. Even the ones

where you pull the excluder and just move it over to

make the cable go on backwards to the way it did

before.

 

If you have a camera, I'd love to see your card edge

to 3.5 header socket converter. A link to buy the same

thing would probably be just as good. My apologies if

you already did that before. Post number please then.

 

So you might be wanting pictures of my NEC as DS0 modded?

Well apologies first for the cheapest phone LG makes,

I'll finish it and then I'll try...

 

post-13325-0-94436200-1554070995_thumb.jpg

 

Pin 2 graphic can just be seen on the very left side,

and bent pins for better access for the nippers are fine.

 

 

post-13325-0-60037700-1554071018_thumb.jpg

 

Pin 2 almost entirely out of screen to the right, pin

one not seen at all, but the hole that used to be pin 3

is wide empty spot paired with pin 4. You can follow

the trace from pin 12 to the surface mount chip and

start counting from 19 to verify the end FDC pin count

is 26 as per better photo from link already given in

last post.

 

Construction tip - notice my HDR solder jumper is on

with small solder blob and the one in the link is open.

I also have T/H jumper soldered where his is open as

well. I don't think it's important to the XF-551, but

a PC might holler some? I'll wrestle with those problems

another day if they get in the way.

 

I didn't see the hole he drilled just above and left of

pin 12 to 'cut' that trace until I rotated that captured

picture. But that is one super fine drill bit that did that.

We happen to make use of that very trace for DS0 signal

from pin 10 to reach the FDC - please do not cut it as

he did. I think this way to do the same thing is easier.

And no surface mount soldering needed.

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I was actually asking about pictures of the mod; which you have provided. Thanks. I can't imagine why the sony doesn't work because the slider switch is clearly designed to set the drive number.

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It could be broke, can't know until a PC confirms it's

a doorstop for sure.

 

Did you notice that the TEAC has jumpers for DS0 in post

#91?

Should be almost as easy as the sony switch to try it.

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Will a 5.25 drive work with the Hyper XF version B EPROM or do I have to change EPROMs everytime I try out a different configuration?

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Will a 5.25 drive work with the Hyper XF version B EPROM or do I have to change EPROMs everytime I try out a different configuration?

 

A is for 5.25, B is for 3.5

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you can stack the proms and add a switch or use a larger prom, program more than one version and use a switch to select as well, it's been written about and documented in various places including AtariAge....

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Hello hueyjones70

 

If the disks use the same density and have the same amount of sectors, "yes". Which probably means "no".

 

Sincerely

 

Mathy

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