Modification of floppy cable for sony drive

[_ThEcRoW]

Hello guys, i have a pair of sony drives MFP520, that are useable on amiga computers, but a modification in the cable is needed. How is the most effective/easier way of doing it without damaging the cable?. Itried to open up one cable, but i got the feeling that it could be broken at any moment, i mean the plastic that acts as closer. I know what pins i have to modify, but have a problem with the opening of the cable, as never had the need of opening one before. Any suggestions?. Thanks in advance!!!

[Franchute13]

Hello.
There is an easy modification to perform and is done on the drive. This modification is NOT compatible with the Sony MFP 520.
On a MFP 920 is functioning properly.
This in Spanish
http://www.retrocomputacion.com/cgi-...num=1169698625

In Spanish
Hola!, Existe una modificacion facil y rapida que se hace sobre la misma diquetera pero la probe sobre dos MFP520 y no funciono. Busca una Sony MFP 920 ahi si anda la modificaicon.

[prowler]

Originally Posted by Franchute13

Hello.
There is an easy modification to perform and is done on the drive. This modification is NOT compatible with the Sony MFP 520.
On a MFP 920 is functioning properly.

As the MPF920 modification is incompatible with _ThEcRoW's Sony MPF520 drive, I presume you're posting that link merely to show an example workaround which obviates the requirement to modify the cable.

[TomCrazy]

There are floppy cables out there you can get from ebay and other places, so why would you want to do this without damaging the cable?

I didn't want to make any modifications to my original Amiga floppy cable, so what I did was to take a PC floppy cable with three 34 pin connectors on it. (One that goes into the motherboard and two that goes to floppys drives.)
I then cut off the part of the cable that had a twist on it. This left me with a straight connected floppy cable with two connectors, similar to an Amiga floppy cable.
Using an exacto knife, I then separated the wires I wanted to work on from the rest of the wires on the ribbon cable. (But not the whole way, only enough to be able to work on them.)
I then cut the wires, stripped and tinned them and connected them together in a sort of cross-connection. I used heat shrink tube for isolation.
I guess I don't have to mention which pins I connected to where since you already know about that.

I think this is the best way to do it. Trying to pry open the connector will most likely only damage the cable to a point which will render it completely useless as a floppy cable.

The smart thing about doing this to the cable and not the drive is that any PC floppy drive can be connected and tested with the Amiga without having to make any modification to the drive.

[_ThEcRoW]

Will try the exacto knife suggestion. Of course the cable i'm using is'n the amiga original, it´s a pc cable i had lying around. The modification of the drive that was suggested is for drives that couldn´t be used as is on the amiga, and hence the modification needed. But i got lucky to get ahold of two sony drives and i discovered that they can work straight away, and only needed to change the wires in the cable. Will try when have time and post the results here. Thanks for the replies!.

[Sandro]

any PC floppy drive will work with the modified cable + the diode hack for the ready signal
but also internally you must hack the floppy drive to works only in DD mode, ( disabling the high density switch)
otherwise if you insert a high density floppy the drive will work in High density mode it will not read/write those disks correctly

[prowler]

Originally Posted by Sandro

...otherwise if you insert a high density floppy the drive will work in High density mode it will not read/write those disks correctly

You can get around that by covering the HD sense hole in the disk enclosure with sticky tape, which prevents the switch from detecting it.

BTW, it is not recommended to use HD disks formatted in DD mode. Nevertheless, some drives do seem to work well with HD disks used in this way.

[TomCrazy]

Originally Posted by Sandro

any PC floppy drive will work with the modified cable + the diode hack for the ready signal

The diode hack is a terrible modification that should not be applied to any floppy disk drive. Performing the diode hack is like asking for trouble. That hack is probably invented by someone who doesn't know enough about electronics to understand what hooking up a diode like that actually means in terms of operation of the disk drive. I won't go into all the technical details in this post, but it basically comes down to unreliable logic operation because of the voltage drop across the diode as well as the ready signal telling the Amiga that the drive is ready when it's actually not, causing big problems especially during write operations of the drive.

[Sandro]

Originally Posted by prowler

You can get around that by covering the HD sense hole in the disk enclosure with sticky tape, which prevents the switch from detecting it.

BTW, it is not recommended to use HD disks formatted in DD mode. Nevertheless, some drives do seem to work well with HD disks used in this way.

the sticky tape on disks is not a clean solution for me, is better to shortcut the HD switch then the drive will recognize all disks as DD
I never found problems with HD floppies, in fact I always purchased HD floppies because DD floppies were not easily available
some of them have 20+ years they are still working very well

The only difference between HD disks and DD disks is the coercivity of the oxide used, this theoretically is a difference but this is not a problem if the floppy drive is enough good to magnetize the disk correctly

[Jope]

Originally Posted by Sandro

the sticky tape on disks is not a clean solution for me, is better to shortcut the HD switch then the drive will recognize all disks as DD

This is not a cookie cutter solution. I've tried that myself, but some drives stop recognizing disk changes if you short circuit the HD switch.

[TomCrazy]

@Jope
Then these drives must be configured in a way which requires both the HD switch and the disk detector switch to be released at the same time for the latched "disk-in-drive" signal to reset back again to the other state. That's interesting. I have personally never seen any drive that does this, and I'm kind of wondering what the purpose of designing a floppy drive like this might be. The only thing I can think of is higher reliability, since both switches need to be in the UP position in order for the drive to trigger the "disk out" state. And we all know that these switches easily can start getting intermittent over time.

However, even with the drives that have this implemented, it should be fairly easy to modify them to work around the problem and have them work in the way Sandro explains, hence not having to put tape over the hole on all HD disks.
For example, the switches could be set up in a sort of master-slave configuration, where the disk detector switch acts as the 'master' which controls which signal state the HD detector switch (which is then no longer in circuit) is sending to the logic circuitry. It really shouldn't have to be any more difficult than that.
After all, having to put a piece of tape over the holes of every HD floppy disk is not exactly the ultimate solution.

One easy way to check if a drive has this kind of HD switch / disk detector switch dependent latched circuitry is to simply push down the HD switch with a small screwdriver or something while pushing down and then releasing the disk detector switch with another. It's easy to notice whether or not the drive detects the (in this case faked) disk change when only the disk detector switch is being released.

[Jope]

Just dismantle a 3.5" disk, take the plastic lifter out from underneath the paper liner, and stick it onto the tray of the floppy drive so that it always presses down on the HD sensor when a disk is in.

Cheap and easy. :-)

[_ThEcRoW]

What's the diode hack you are referencing?. I never heard of it, but since you said it isn't worth, will not try that.

[Sandro]

Originally Posted by _ThEcRoW

What's the diode hack you are referencing?. I never heard of it, but since you said it isn't worth, will not try that.

do not listen tom crazy member, he don't know what is talking about
the diode hack is this, between pins 34 and 16



make it otherwise the ready signal will not work
lot of floppy games will not work and xcopy also will not work

you don't need a germanium diode, any rectifier diode like 1n4001 will work fine

[TomCrazy]

@ThEcRoW
The diode hack is exactly like Sandro has showed in the picture.

@Sandro
I find it rather amusing that you claim that I don't know what I'm talking about. By doing so, you are yourself proving that it is you who don't know what you're talking about.
In fact, I could easily prove to you that what I'm saying is correct. If you knew everything about the signals on the floppy disk drive interface including timing and other parameters, and if you had conducted extensive tests to learn more about it, then you wouldn't had said that I don't know what I'm talking about.
I would never have posted this information if I did not know what I'm talking about.

Yes, the ready signal is needed for trackloaded games and xcopy. But like I said, using the diode hack can give lots of problems with write operation and therefore it is not a recommended hack.
There are much better ways to do it that includes using logic circuitry to generate a ready signal with the correct timing.

[Sandro]

Originally Posted by TomCrazy

@ThEcRoW
The diode hack is exactly like Sandro has showed in the picture.

@Sandro
I find it rather amusing that you claim that I don't know what I'm talking about. By doing so, you are yourself proving that it is you who don't know what you're talking about.
In fact, I could easily prove to you that what I'm saying is correct. If you knew everything about the signals on the floppy disk drive interface including timing and other parameters, and if you had conducted extensive tests to learn more about it, then you wouldn't had said that I don't know what I'm talking about.
I would never have posted this information if I did not know what I'm talking about.

Yes, the ready signal is needed for trackloaded games and xcopy. But like I said, using the diode hack can give lots of problems with write operation and therefore it is not a recommended hack.
There are much better ways to do it that includes using logic circuitry to generate a ready signal with the correct timing.

of course there are better ways to implement a better ready signal with logic circuitry,a correct timing of the ready signal is 0.5 ms
but we're talking here about only cable modding, without the diode hack XCOPY will not works and some games will not work

btw
if you know a simple way to implement a ready signal better than the diode hack plz post it ,I will be the first to test it

[hooverphonique]

Originally Posted by Sandro

of course there are better ways to implement a better ready signal with logic circuitry,a correct timing of the ready signal is 0.5 ms

well, if RDY was always asserted 0.5ms after SEL/MTR, then there would be no need for RDY - RDY is there, because different drives may have different spin-up times. The diode hack basically tells the amiga that the drive is up to speed immediately when turning the motor on, which may work in some cases and not in others..

[TomCrazy]

Originally Posted by Sandro

of course there are better ways to implement a better ready signal with logic circuitry,a correct timing of the ready signal is 0.5 ms
but we're talking here about only cable modding, without the diode hack XCOPY will not works and some games will not work

You are right in that xcopy and trackloaded games won't work without a ready signal. And yes, the diode hack will make trackloaded games and xcopy work. However, it can also result in problems during write operations of the disk. I know there are other people too who have noticed this because I've read other threads as well where people have gotten the same results when testing the diode hack.
It doesn't necessarily have to be like this with every disk drive, but you're very likely to run into this problem if you test it with several disk drives.

I guess it's up to each and everyone what they prefer. Either a diode hacked cable with working trackloaded games but with write operations that will risk reporting read/write error and potentially even destroy data on the disk, or a hacked cable without the diode in place which will then work fine in Workbench witout any strange write problems, but won't work with trackloaded games.

In my opinion, it's better to not use a diode at all. If you're going to do something, you might just as well do it right or you might run into unwanted trouble like in the case with the diode hack.
I am in the opinion that if you're going to implement a ready signal, you're much better off actually designing a logic circuit that generates a true ready signal that is an exact representation of the ready signal found on real Shugart floppy drives.
Either that, or skip the ready signal completely. That will spare you a lot of headache.

What hooverphonique is saying is very much correct. I haven't checked and compared the exact spin-up times between different floppy drives, but I know for a fact that the ready signal is there in order to tell the Amiga when the drive is ready to receive a new command and/or perform a new operation. This is an outgoing signal going from the floppy drive to the floppy logic on the Amiga motherboard.
By hooking up the diode between pin 34 and 16 like that, you're just passing the motor on signal on to the pin for the ready signal, making RDY become low (ready) as soon as the disk drive spindle motor turns on. This is extremely far from how a genuine ready signal looks like, and the result will be that the floppy controller on the Amiga thinks that the floppy drive is ready when it's actually not. That is why this diode hack is not a very good solution and should not be performed.

Also, the way you presented the hack (hooking the cathode of the diode up to pin 16) is even worse than the original diode hack I found on Aminet. The one I found on Aminet involves hooking the diode up to pin 10 instead of pin 16. (Pin 12 instead of pin 10 if it an unmodified PC drive.)
If you hook the diode up to pin 16, then you will get problems when having an external floppy drive connected to your system and both floppy drives are operating at the same time. When DF0: is spinning, it will interfer with the ready signal being generated in DF1:, so DF1: cannot send a proper ready signal to the Amiga.
In order to at least have some kind of chance of making it work together with an external floppy drive, you should hook the diode up to pin 12 on the PC drive instead so the ready signal is following the drive select on the floppy drive and not the motor on signal.

Originally Posted by Sandro

do not listen tom crazy member, he don't know what is talking about

Originally Posted by Sandro

btw
if you know a simple way to implement a ready signal better than the diode hack plz post it ,I will be the first to test it

First you tell me that I don't know what I'm talking about, and shortly thereafter you ask me to share information with you? Why would you even be interested in such info from someone who "doesn't know what he's talking about"? And why would I be interesting in sharing it with someone who doesn't believe in what I say?
Anyway, I will still answer your question for the sake of other members of this forum who might come across this thread, and who actually choose to believe in my words a little bit more.

If you just want to do a simple hack to the floppy cable, rerouting the wires and doing the diode hack (with a schottky diode or equivalent) is really the only thing you can do. I did not mean to say that you can easily put a lot of logic chips on the floppy cable. Of course you cannot do that. What I meant was that if you're going to generate a ready signal, you might be much better off designing a logic circuit that does this correctly, in a way that actually works without causing problems.

A modified cable works best with old PC floppy drives that have the ready signal on board, because with the rerouted cable, a genuine ready signal will then be sent to the Amiga.
If you want to use PC floppy drives that doesn't have the ready signal on board, then you need a circuit that is generating the ready signal in a correct way to make it work well.
Ian Stedman has already designed such a device, and it can be ordered on his homepage. This device is rerouting the signals and generating the ready signal with two 74-series SOIC14 chips.
I have not tested his floppy adaptor yet to see how well it actually works and how the ready signal generated on that board compares with that of a Shugard drive, but I'm quite sure it will work much better than the diode hack anyway. And the adaptor is quite cheap too, only priced £13.50 on his homepage.
I think Stedy's adaptor is a much better alternative than hacking a floppy cable, although I have yet to try the adaptor out someday.

Btw, thanks for offering to test my ideas, but I have enough equipment to test them myself so I'm not really in any need of help there.
Besides, if you want a ready signal generator circuit, Stedy's floppy adaptor is already readily available for that very purpose.

Ooops, I happened to ramble on with a lot of things again that I don't know anyting about. I'm really good at making things up today, aren't I?

[Hewitson]

Originally Posted by Sandro

you don't need a germanium diode, any rectifier diode like 1n4001 will work fine

The reason a germanium diode is recommended is because it has a much lower voltage drop than a silicon diode. Anyone performing this mod would be silly to use anything other than a germanium or schottky diode.

[Sandro]

Originally Posted by Hewitson

The reason a germanium diode is recommended is because it has a much lower voltage drop than a silicon diode. Anyone performing this mod would be silly to use anything other than a germanium or schottky diode.

yes I know germanium diodes have low forward voltage something like 0.2 compared to 0.6 standard diode
I wonder what would be the difference in this mod
ie remember the diode hack is not 100% accurate