Hit and miss writing ADF's

[vimfuego]

Hi All,

So I've been busy writing some ADF game files to floppies (High Density) using TSGUI, but I am finding that they are not working at least 50% of the time.
When I say not working, the game will sometimes get to the main screen but usually fails after that or if I have to swap disks, like the disks are faulty.
I am not sure if I am just having rotten luck with downloading bad ADF's or I have a hardware problem. I do have TSGUI to set to verify what it writes and it never seems to error.
Any thoughts?

Finally, anybody got an ADF of the game Logical that works on an A1200 (stock)? I've tried several but it will not even run.

Cheers

[thomas]

floppies (High Density)

It's most likely an effect of using HD disks in a DD drive. HD disks need higher precision which a DD read/write head cannot do. It might read a track successfully once but fail the next time. Try to find some DD disks if you want to store the games reliably.

[vimfuego]

Well, I just had lots of them around from the days before USB memory sticks and blank CD's, I thought I'd give it a go.
I have a few DD disks (magazine cover disks), I might try with them on the same programs I am having problems with and see if it makes a difference.

[prowler]

Originally Posted by vimfuego

Hi All,

So I've been busy writing some ADF game files to floppies (High Density) using TSGUI, but I am finding that they are not working at least 50% of the time.

Hi vimfuego,

Thomas is right. The High Density disks are definitely causing the problem. I have the same trouble myself.

Originally Posted by vimfuego

I have a few DD disks (magazine cover disks), I might try with them on the same programs I am having problems with and see if it makes a difference.

Using DD disks will solve the problem, unless they have been stored in less than ideal conditions and have deteriorated.

[Supamax]

This is something I ever feel hard to understand .
I mean: Ok, I noticed myself that HD disks are not as reliable as DD disks when used with Amigas (with DD drives). But I don't understand why.
The magnetic surface is denser (and its quality is higher)... so why should they cause problems when accessed by DD drive heads?

[8bitbubsy]

Also check if your amiga floppy drive is very "dusty", cleaning it might help! Carefully use a q-tip to clean the read heads, but DON'T use force, as you might disallign them!

Also, use DD floppies, as the guys here are recommending. Then you'll be set

[Photon]

Originally Posted by Supamax

This is something I ever feel hard to understand .
I mean: Ok, I noticed myself that HD disks are not as reliable as DD disks when used with Amigas (with DD drives). But I don't understand why.
The magnetic surface is denser (and its quality is higher)... so why should they cause problems when accessed by DD drive heads?

How do you know the quality is higher? I bet all your DD disks are 15 years older than your HD disks Even if they're not, I'd need some kind of proof of manufacturing process quality

Anyway, can we file this as (final?) evidence to all the jerks who claim using HD disks for DD Amigas is fine please.

[Supamax]

Originally Posted by Photon

How do you know the quality is higher? I bet all your DD disks are 15 years older than your HD disks

You bet... and you win! .
Ok, I probably used a wrong term; I didn't mean that a HD disk has more quality (and not related to time, that's sure! ) than a DD disk.
I was meaning that the HD disk's surface is more dense (they have to hold 1.67 MB instead of 880 KB).
So, when a DD head "moves" above DD tracks saved on a HD disk, it should encounter much more magnetic particles (twice, in theory? But I suppose they are less, although much more than DD tracks, am I right?).

Wait! Perhaps I had an intuition... Could it be that HD magnetic particles are too small (related to DD particles) and this is not "appreciated" by the DD drive heads?

[Photon]

Can't remember all the details, but I think it was that HD uses a thinner magnetic layer to more quickly flip bits with the magnetic field of the r/w head, and using a lower current.

Less material=more easily magnetized=more easily affected by magnetic field changes when it's outside the drive. The reason most DD disks are buggered is cos the owners have moved 3 times, put them in a cellar or attic for years exposed to the seasons, and rewrote those disks 61 times each when they were young and hot-blooded 20 years ago. Sort of

Hence the vicious attack on your statement!! :P

New ones are sold for the benefit of synthesizer users etc on misc. auction sites for about 5€/10 pcs. No idea about their quality, probably made in China/Asia, doesn't mean they're bad.

Hm... should try a pack just to check, but atm I'm using up the couple hundreds used ones I have. I slide open each disk and rotate the center and check for any dust or particles, if it doesn't come off when I blow on it, I throw the disk. If I get any 'ticking' or 'eee-aww' retries at all with DMS, I throw it away. If it works on the first go with 0 verify errors I keep it. It's the only way or you go crazy

Usually it's the very first tracks or track 70-80 that have given up. The latter could be that the 20 years old material has deteriorated beyond the point where it fails to hold dense data without neighboring bits affecting.

Also, I recommend the floppy cleaning kit from Amigakit. Use it in relation to how many diskswaps you make (I clean the drives once a month or so, I don't use floppies much.)

[thomas]

Originally Posted by Supamax

But I don't understand why.
The magnetic surface is denser (and its quality is higher)... so why should they cause problems when accessed by DD drive heads?

A HD disk has twice as many bits in the same space as a DD disk. This means that a head which should write to a HD disk even in DD mode has to be able to switch from 0 to 1 or vice versa twice as fast as that for a DD disk. A DD head is not able to do that so it writes only every second bit reliably and the other bits inbetween have random values, depending on in which state the head was when switching from on bit's value to the next bit's value.

[vimfuego]

Well the problem has really only come about because I have a stock A1200 (except for the CF) so running games from WHDLoad is not really an option with 2Mb of RAM.
This seemed like it was going to be an easy way out with all those HD PC disks I have sitting in the garage. Oh well.
I did find that one game (spans 2 disks) works fine, so it's possible, just low success rate from what I've found, maybe it's even brand specific.

[Retro1234]

The only disks ive been able to get are HD and ive not had any problems - the only time ive had problems is when using HD with CrossDos formated to 720kb -Do the ADF images your trying to write work under winUae Quickstart A1200?

[dlfrsilver]

Guys, amigakit is selling DD disk brand new, you can buy those by 50 or 100. Why bothering with 1.44mb disks which are really cheap and destroy themselves quickly ?

heh !

[Supamax]

Originally Posted by Photon

Can't remember all the details, but I think it was that HD uses a thinner magnetic layer to more quickly flip bits with the magnetic field of the r/w head, and using a lower current.

Less material=more easily magnetized=more easily affected by magnetic field changes when it's outside the drive.

Hmmm, interesting! This could be the right reason!
It makes sense.

Originally Posted by thomas

A HD disk has twice as many bits in the same space as a DD disk. This means that a head which should write to a HD disk even in DD mode has to be able to switch from 0 to 1 or vice versa twice as fast as that for a DD disk. A DD head is not able to do that so it writes only every second bit reliably and the other bits inbetween have random values, depending on in which state the head was when switching from on bit's value to the next bit's value.

No, I don't think you're right... An unformatted disk has no "predefined" bits. It's only a layer of magnetic surface.
It's not like a CD-R, which has a physical spiral on which the burner will lay down the bits (the "0" and "1" sequence) with a certain frequency (/distance between bits).
A DD head (or HD head in DD mode) which will write on a HD disk will not have to switch bit states twice as fast! It will format the disk with a same structure (and bit density) as it would when writing to a DD disk.
Furthermore, there will be no "bits inbetween". The surface is *all* written/formatted, all (DD) bits are written. Simply, the denser surface is not used at its best.

It's similar to when you format a 5,25 floppy with a 40-tracks drive or an 80-tracks drive. In both cases the whole surface is formatted. There'are no unformatted tracks inbetween.
What is different is the "radial width" of the tracks: tracks written by a 40-tracks drive are bigger (circa twice) than those written by an 80-tracks drive.

[prowler]

Originally Posted by dlfrsilver

Guys, amigakit is selling DD disk brand new, you can buy those by 50 or 100.

Hi Denis,

Do you have a link for those, please?

[TCD]

http://amigakit.leamancomputing.com/...?keywords=dsdd
On their main page it's at the top right corner

[prowler]

Thanks, TCD! (That link just about covers it. )

I'd have looked for it myself, but I'm still trying to catch up with Today's (many) Posts!

[Supamax]

Originally Posted by prowler

I'm still trying to catch up with Today's (many) Posts!

Hope I didn't write anything sounding idiot about DD/HD...

[prowler]

Originally Posted by Supamax

Hope I didn't write anything sounding idiot about DD/HD...

Hi Supamax,

Rest easy, mate.

Your posts, as well as those from Thomas and Photon, have tried to explain the reason for the difficulty some users experience when using HD disks in Amiga DD drives, and all have included elements of truth.

I have not yet seen a definitive and authoritative statement on this subject which leaves no room for debate. And that is the underlying problem.

A further problem is that some users - Boo Boo, for example - have no difficulty at all in using HD disks in DD drives!

[Supamax]

Originally Posted by prowler

A further problem is that some users - Boo Boo, for example - have no difficulty at all in using HD disks in DD drives!

There's another strange fact to consider: when writing A-Max disks with Disk Copier & Converter v6.0 (*) (see this post from the A-Max thread: http://eab.abime.net/showpost.php?p=515473&postcount=97) I got better (more reliable) writes using HD disks... but you didn't share my experience with your A1200... what the heck!

(*) I use v6.0 here as an example, since v7.x is another world. It perfectly works both reading and writing on DD disks.