New Floppy Drive - Sony MPF920

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New Floppy Drive - Sony MPF920

Postby techie_alison » Wed Apr 04, 2007 6:52 pm

Hello,

I've been trawling through the various Atari and Amiga posts, so went off and did my own thing today. I now have this drive *properly* reporting the Drive Change signal to the ST. There is no more of this bodging it so that it checks the disk continually. It now properly recognises if a disk has been changed.

a.) With a GEM drive window open pressing ESC always re-read the drive.
b.) Closing the window, changing the disc, and opening another window, is where the ST will get confused with all of the other hacks.
c.) Closing the window, not changing the disc, and opening another window does not re-read the disc.
d.) Closing the window, changing the disk, and opening another window does re-read the disc.

Aside from the DRIVE0 select jumper being changed. A wire is ran from the retro Pin-1 (N/C on modern drives) to the actual Disc Change switch next to the Write Protect.

See images that follow;
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Postby Dew-It » Wed Apr 04, 2007 8:55 pm

Good work Alison. I have the older model(s) 5 Sony MPF920-E. It has a jumper that you can change for drive select 0. But the one you have is probably the Z or newer model 2006. When I get a Desoldering Station I'm going to put 1.44 Floppy upgrades in my two 1040STF and my 1040STe and also have external 1.44 drives as well for each ST(e). I bought my 1.44 Floppy drive upgrade from Exxos. Might even add Dual TOS to the 1040STe, Have TOS 2.06 and I'm not sure which would be better for backwards compatabilty TOS 1.02 or TOS 1.04. Greenious has Atari_STE_TOS_upgrade_v2.pdf which tells you how you can have two TOS operating systems on one two eproms and you can switch between the two different TOS's.
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Postby kym » Thu Apr 05, 2007 2:10 am

This chick is smart

Having the older model Sony MPF920-E , should make no difference, apart
from a revised circuit board layout basically the same drive. The switch is
still in the same place , and should work the same, Now if some one could
tell me how to switch the stepping rate in hardware instead of software ?

Kym :D

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Postby Dew-It » Thu Apr 05, 2007 3:05 am

Nope they are different. http://support.dell.com/support/edocs/s ... umpers.htm
If you mount the jumper horizontially the drive is DS0 compatable with Atari ST.
Vertically and it is DS1 compatable with a PC. Plus I did'nt need the extra wire. Exxos recommanded the Sony MPF920-E, because it was very compatable with the Atari ST and you did'nt have to do much to get it to work correctly. My bad I have it wrong. Horzontially compatable with Atari ST and verticallly compatable with PC. I just looked at the back of my drive.
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Postby kym » Thu Apr 05, 2007 4:12 am

Slight differences will not change the way this works. I have in front of me
a MPF 920-E and the jumpers are not like that , they are surface mount resistors as in the pictures above : Manufactured in June 2002 .
SEL 0 and SEL 1

Where do you connect pin 1 of the modified drive to on the ATARI ???

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Postby exxos » Thu Apr 05, 2007 9:02 am

kym wrote:This chick is smart

Having the older model Sony MPF920-E , should make no difference, apart
from a revised circuit board layout basically the same drive. The switch is
still in the same place , and should work the same, Now if some one could
tell me how to switch the stepping rate in hardware instead of software ?

Kym :D


OH that old thing, well my kit does just that, even though several people flamed me on usenet for saying it cant be done. I've been fitting 1.44 kits to ST's for over 10 years, I find it works well enough :-)

Eventually I will publish the diagram, though actually have to draw one first, 8O

BTW, the drives I use are those 2006 versions, with SEL1/SEL0 I keep having people ask me about it though never got around to taking images, so thank Aly for doing that :-) Can I steal your pics for my site plsssss :))

Chris

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Postby Dew-It » Thu Apr 05, 2007 11:46 am

kym wrote:Slight differences will not change the way this works. I have in front of me
a MPF 920-E and the jumpers are not like that , they are surface mount resistors as in the pictures above : Manufactured in June 2002 .
SEL 0 and SEL 1

Where do you connect pin 1 of the modified drive to on the ATARI ???

Kym

Sorry but mine does work the way it shows above in my previous message. I'm not sure when mine was manufactured, it looks like 1997. So they have made some revisions since then. It's all good as long as it works for you.
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Postby ppera » Thu Apr 05, 2007 12:19 pm

Whole catch to make floppy drive Atari ST compatible (in media change detection meaning) is to ensure this: when no floppy in drive, and it is selected, then WP line must be low.

http://www.ppest.org/atari/flomodam.html

It can be done with any drive - all have somewhere sensor for floppy in/out.

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Postby pop » Sat Apr 07, 2007 5:00 pm

hi
will the st use this as a 720kb drive?
thanks :)

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Postby Dew-It » Sat Apr 07, 2007 5:21 pm

Yes it will.
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Postby MiggyMog » Sun May 27, 2007 5:02 pm

In addition to modding this for the drive select / Media change issue, can the signal for for HD detect be taken directly from the switch SW3 on the MPF920 for use with chris's HD mod?
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Postby exxos » Mon May 28, 2007 6:03 pm

I am still slightly confused about the media change, maybe someone can remind me of what the actual issues are ?

I remember on some early ST's that when you changed the floppy the ST would not detect a new floppy, even presses ESC to refresh, with or without the floppy , it would not detect a change. Though since then I have never seen this problem.

The only thing I can think of was on programs like protecker which never seemed to like disc access, you could boot off the protracker floppy, then in load a tune in of fthe same floppy, then change the floppy and when you saved it corrupted the floppy, though I only saw that in protracker. Though its floppy IO seemed pretty iffy at the best of times anyway.

I wonder if there are some machines which suffer and some dont, I think if using GEM for example, that if you change the floppy, then you need to press ESC to refresh the window. I know for some reason on a few ST's that pressing esc did not work, though I have not seen this problem much at all. I think it was a bug in pre TOS 1.04. The floppy IO is iffy for some reason on pre 104, I don't know why, though its why I don't recommend using the upgrades on pre 104 tos.

for some reason pre 104 versions come up random disc errors. Most do not even notice the problems but they are there. I don't think any real study has been made to all of this, its not really needed.

Back to the MPF drive, using with 104 or above should be no problem at all. I only ever used GEM so can't really speak for other problems beyond that. I think the old brick drives with the addon board were the ones with the issues essp with pre 104 TOS.

I don't recall any disc change problems with the epson drives on 104 machines. Though those are the only ST's I have seen here. The drive may have an effect, though on pre 104 machines the disc IO is iffy anyway so theres no point in blaming the hardware. *if* 104 is fitted and still problems, then I would say there is a problem with the floppy drive.

I've not heard of any issues with the sony mpf series with tos 104. Even so the disc IO seems strange, while developing the hardware hack for the 1.44 mod, the seek rate commands fire at the WD1772 like 50times each disk access. very strange.

I would suggest that people put up a page and list the problems and the spec of thier machines, maybe we can see exactly where the problem is then. I would suggest that anyone who does not have media change issues not to worry about it. I managed to fire 2,000 floppies though my ST while copying my collection with no issues..

HTH
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Postby MiggyMog » Tue May 29, 2007 8:24 pm

I lost a couple of Music Modules I done a few years back & suspect it was due to media change detection when swapping disks as I got a corrupt FAT/DIR. That was using tos 1.62 & a standard Epson drive. I suppose it could be down to the routines they used in the programs as you say. They tended to shut the drive routines off while using the CPU intensive stuff so I suppose any interrupt would be ignored in that case.

I tended to use Audio sculpture/Esion,Noisetracker,octalyser. Not sure which I was using when they two were scrubbed but I remember the Dir being dogy a few times but not always writing back to the disk thankfully!


Any way back to my original question:-

Is it ok to take the HD detect straight from the switch & connect to the Pin on the board as above or is there a better place to pick up the signal?

Also..

I had done the media detect as per ALi & KYMs advise, although I prefer Ali's just when needed as opossed to the always on kyms old thread had.

BTW is the Drive 0/1 select the only mod that is really needed in your opinion then Exxos? and is it ok just to bridge it with a bit of solder as per kyms advise if you loose the .5mm crumb of a resistor?

I don't want to blow the thing up...

I still need to dremmel the pins shorter & sink it a bit so the drive can fit above it once I test if I have killed it already. I read the should sit on chip bit after I had painstakingly solder all the pins, I'm a lame ass like that you see....
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Postby exxos » Tue May 29, 2007 8:59 pm

MiggyMog wrote:I lost a couple of Music Modules I done a few years back & suspect it was due to media change detection when swapping disks as I got a corrupt FAT/DIR. That was using tos 1.62 & a standard Epson drive. I suppose it could be down to the routines they used in the programs as you say. They tended to shut the drive routines off while using the CPU intensive stuff so I suppose any interrupt would be ignored in that case.

I tended to use Audio sculpture/Esion,Noisetracker,octalyser. Not sure which I was using when they two were scrubbed but I remember the Dir being dogy a few times but not always writing back to the disk thankfully!


Any way back to my original question:-

Is it ok to take the HD detect straight from the switch & connect to the Pin on the board as above or is there a better place to pick up the signal?

Also..

I had done the media detect as per ALi & KYMs advise, although I prefer Ali's just when needed as opossed to the always on kyms old thread had.

BTW is the Drive 0/1 select the only mod that is really needed in your opinion then Exxos? and is it ok just to bridge it with a bit of solder as per kyms advise if you loose the .5mm crumb of a resistor?

I don't want to blow the thing up...

I still need to dremmel the pins shorter & sink it a bit so the drive can fit above it once I test if I have killed it already. I read the should sit on chip bit after I had painstakingly solder all the pins, I'm a lame ass like that you see....


I think protracker was the one with iffy disk IO, I thin noisetracker was fine, at least I only knew one one tracker which corrupted floppys. I think it was bad bios hacks as those guys did a lot of that kinda thing to gain the speed.

I can't really comment on the media change, I don't know anyone or heard of anyone doing any mods. In GEM you press ESC to update the window when you change floppy, if you dont press ESC then *maybe* it would corrupt the new floppy, though I am not sure if GEM updates the FAT tables in RAM each disk access. its been over 10 years since I went though all this. I never had any problems by just pressing ESC to update the floppy window, its common sence really.

If the window does not update, then only a reboot of the machine will solve this. Though I can only recall one or maybe 2 ST's doing that. All the ST's I have ever updated I always used TOS 104 and the MPF drives, never any problems found there.

If media change is to be supported, then the GEM windows would need to be refreshed as soon as you put a new floppy in without pressing ESC. I can't remember if the FAT are read each drive access. I did write a program years ago to read the ram locations and check it with the floppy in the drive. I *think* it updated rather well and more than expected. this suggest GEM/BIOS knows the floppy has changed.

It would make more sence for the BIOS to read the floppy boot sector each drive access, if it differs from the ram version then it gets updated. Thats how I would think it would be done. I can't see any reason why the ST would need to monitor a switch to do this.

I think people will know that no matter what you did with the floppy, the GEM window would just not check the drive and update the window. I think this was a bug in the BIOS routines, I know for a fact they are iffy on pre TOS104. apart from protracker I am not aware of any media change issues. I tests TOS104 and the MPF drives a lot and always updated the window and always checked the drive. no matter what you did it would still read the drive.

The only issue I can think of if if you are copying files and do not press ESC to update the window before copying files to maybe another floppy. I am sure someone could test that out on a real ST.

In anycase, alter the drive select on the mpf drive is all that is needed to get it to work. I am not aware of any problems, not saying there isn't any, but if this really was a bug then people on the forums would be on about it no end.

I think GEM should re-read the boot sector on any floppy access, read or write. I think it does, and it makes sence to to that. FAT in RAM would be updated so no problem. I can't remember if the GEM window updates after a file copy, its been a few years! I think it does on the falcon, maybe on the ST, someone reading maybe able to answer this...

I think pre tos104 did not work correctly anyway, I know it comes out with random errors, actually CRC errors for no reason at all. you really have to get to know your ST to notice such errors. they are there. I documented this in my 1.44 manual years ago!

Some people claim pre tos104 works fine, not sure why! BIOS will retry CRC 3 times before reporting a CRC error. We all must have seen a floppy copy and at some point it slows down on one track then speeds up again.. that is a CRC error, if after 3 trys it still fails, THEN GEM reports a CRC error. have to really watch whats going on!

I am not aware of the ST checking media select, I know there has been a lot of talk about it in the past, though IMO I think it was workarounds for bugs in TOS more than anything. Isn't there media change bug fixes for use in the auto folder ? Really all it needs is for the bios to re-read the FAT table each time a read or write is done. easily done in software.

Maybe someone reading can verify the points above ? I don't have any Atari stuff at my new house so can't check anything. all it needs is a small program to dump the FAT RAM data to screen, change the floppy and wath the FAT locations to see what happens, each read it should update the FAT in RAM....

if not, then if you dont have any problems of strange floppy corruptions like in protracker then I really wouldn't worry about it. protracker seemed not to update the file selector, if you did manage it, it would seem to keep a old copy in RAM and corrupt the floppy anyway. updating ram is a software issue in the program.

apart from older ST's not updating the screen when pressing ESC and protracker floppy problems, I don't know of any other issues....

HTH
Chris

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Postby ijor » Wed May 30, 2007 1:11 am

exxos wrote:I am still slightly confused about the media change, maybe someone can remind me of what the actual issues are?


There is some old thread here where Ppera and me described the issue.

ST drives (as most DD ones) don't have media change hardware support. Then what TOS does, it to poll the Write Protect signal during the vertical blank. When you remove or insert a disk, the Write Protect signal briefly changes state. So TOS knows "media was changed".

This works as long as the drive always updates the Write Protect signal. Newer drives however, do not. They tri-state most signals when they are not "ready". And they are not ready when a disk is being inserted or removed.

Some older HD drives have jumper to configure the "ready" condition. In this case you could make the drive behave as original ST ones. It is possible that modern ones still have an internal solder pad, I don't know.

Otherwise you could implement some hardware solution, check Ppera's link.

I know for some reason on a few ST's that pressing esc did not work, though I have not seen this problem much at all. I think it was a bug in pre TOS 1.04.


The exact behavior when clicking ESC depends on several factors and layers, not only on the hardware. So it could be slightly different depending on the TOS versions.

TOS has a second media change management at a higher level (at GEMDOS). It includes checking the serial number on the boot sector. Almost every TOS version implement this slightly different and they are all broken in different degrees before TOS 2. Floppy caching was also changed and this also affects the chances of floppy corruption as a consequence of a wrong media change detection (I posted a detailed description of the issue long ago).

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Postby kym » Wed May 30, 2007 1:48 am

The normal place to get the H/D detect signal is from pin 2 of the
floppy connector, but it can be taken from switch 3 . This will
depend on , the polarity of the signal that is needed.

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Postby exxos » Wed May 30, 2007 4:36 am

ijor wrote:
exxos wrote:I am still slightly confused about the media change, maybe someone can remind me of what the actual issues are?


There is some old thread here where Ppera and me described the issue.

ST drives (as most DD ones) don't have media change hardware support. Then what TOS does, it to poll the Write Protect signal during the vertical blank. When you remove or insert a disk, the Write Protect signal briefly changes state. So TOS knows "media was changed".

This works as long as the drive always updates the Write Protect signal. Newer drives however, do not. They tri-state most signals when they are not "ready". And they are not ready when a disk is being inserted or removed.

Some older HD drives have jumper to configure the "ready" condition. In this case you could make the drive behave as original ST ones. It is possible that modern ones still have an internal solder pad, I don't know.

Otherwise you could implement some hardware solution, check Ppera's link.

I know for some reason on a few ST's that pressing esc did not work, though I have not seen this problem much at all. I think it was a bug in pre TOS 1.04.


The exact behavior when clicking ESC depends on several factors and layers, not only on the hardware. So it could be slightly different depending on the TOS versions.

TOS has a second media change management at a higher level (at GEMDOS). It includes checking the serial number on the boot sector. Almost every TOS version implement this slightly different and they are all broken in different degrees before TOS 2. Floppy caching was also changed and this also affects the chances of floppy corruption as a consequence of a wrong media change detection (I posted a detailed description of the issue long ago).


I cant see how using the WP would work, the WP switch would always be "up" if a floppy had the tab pushed up, no matter if you changed the floppy or not, on that basis, the drive would only see a floopy in the drive if it changed state from moving the tab. I dont know about the WP poll thing, it does not sound like its part of the media change system.

I would agree that about the serial number though, each drive access can check this. Though doesn't the drive heads return to track 0 after each access ? I can't remember offhand, though would tie in that after each disk access that the heads are there already to read the serial number again.

I don't know how it was altered over time, GEM seems to work fine with TOS104 (rainbow TOS), I dont know why, but my falcon with TOT404 seems to mess about no end with floopy acess, you have to change disks like 8 times or soemthing daft to copy 1 single file from one floppy to another. maybe they went overboard in checking media change in latter TOS revisions.

I think TOS104 is fine, and any TOS after that should be fine also, though I suppose that I only used English TOS, maybe like german TOS104 does not work as well, I really don't know that much about all the TOS variations over the years.

I am sure I have a feeling that everything worked better without the media change switch, though it seems the ST hardware does not even check the switch so I guess it does not matter anyway.

For GEM at least, as long as you press ESC to update the window then I really do not see a problem, the floppy will be read and updated in RAM, theres no problem at all. I just put it down to good practice, it sounds like its more of people being lazy and expecting the hardware to do to much. swapping floppys without doing a refresh by pressing ESC or whatever seems a bit dumb to me.

Though like I said before, there have been issues with early TOS, where pressing ESC just does not do anything. It refreshes the window but does not read the drive, it jsut updates from ram, which has not checked the floppy drive. A poor disk cache problem really.

I would say that TOS/GEM reads the floppy boot sector on each IO access, then resets the heads back to track 0, ready to read the boot track on next IO access again. That would seem to me to make the most sence. There is no need to even check any switches then. Its possible the WP could be polled, its a important thing to check. Do not need to spin up the drive to check it so its a fast check.

I remember some games did something like that, they checked the WP line when wanting disc 2, the drive light only came on when you took the floppy out of the drive (WP change). Can't really do the same in GEM as it would slow down the CPU constantly checking the drive in this way.

the WP could be a double check kinda thing also, there is probably a WP check which forces a boot sector read next drive access. Though TOS should really check the boot sector each IO access anyway, or at least it should. I am sure there is auto folder fixes for this, which patch TOS to do just that.

Chris

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Postby ijor » Wed May 30, 2007 5:01 am

exxos wrote:I cant see how using the WP would work, the WP switch would always be "up" if a floppy had the tab pushed up, no matter if you changed the floppy or not, on that basis, the drive would only see a floopy in the drive if it changed state from moving the tab.


The WP sensor is optical, not mechanical (exactly as the HD sensor in HD drives). The function of the tab is just to block the light from the sensor. When you remove (or insert) a disk, there is always a moment when the light sensor is blocked (when the disk is halfway in), and there is always a moment when it is not (when the disk is all the way out). So WP would flip no matter what. You could easily verify this with a multimeter.

I dont know about the WP poll thing, it does not sound like its part of the media change system.


Trust me, it does. And it works exactly as I described it.

You can check the TOS sources in ST Internals, you can also see how media change breaks if you disable the floppy vertical blank.

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Postby exxos » Wed May 30, 2007 10:14 am

ijor wrote:
exxos wrote:I cant see how using the WP would work, the WP switch would always be "up" if a floppy had the tab pushed up, no matter if you changed the floppy or not, on that basis, the drive would only see a floopy in the drive if it changed state from moving the tab.


The WP sensor is optical, not mechanical (exactly as the HD sensor in HD drives). The function of the tab is just to block the light from the sensor. When you remove (or insert) a disk, there is always a moment when the light sensor is blocked (when the disk is halfway in), and there is always a moment when it is not (when the disk is all the way out). So WP would flip no matter what. You could easily verify this with a multimeter.

I dont know about the WP poll thing, it does not sound like its part of the media change system.


Trust me, it does. And it works exactly as I described it.

You can check the TOS sources in ST Internals, you can also see how media change breaks if you disable the floppy vertical blank.



the poll would make sence for an optical switch, though I am not sure I have ever seen a optical WP switch, looking inside my MPF drive, 3 switches and a LOT of dust, any optical switch would get covered in dust after a couple of months making the it not operate at all.

Where did you get WP is optical from ? I would be interested in seeing floppy drives with optical switches, seems that one passed me by!

Chris

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Postby jd » Wed May 30, 2007 11:31 am

Does the sony drive need a 12 volt supply as well as 5v?

I only ask as my external drive has died and i would like to replace it but the power only provides a 5v supply. It was an NEC drive which i can't find anywhere.

Any ideas?

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Postby kym » Wed May 30, 2007 1:46 pm

Go back to page 1 and take a close look at CN2 ( power connector )
in the pictures, Pin number 4 :

There is no trace connected to this pin: this is the 12 volt line:

The Sony uses 5 volts only:

Kym

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Postby jd » Wed May 30, 2007 2:56 pm

sharp eyes, thanks

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Postby ijor » Wed May 30, 2007 7:44 pm

exxos wrote:Where did you get WP is optical from ? I would be interested in seeing floppy drives with optical switches, seems that one passed me by!


You are right and I was wrong, it is mechanical. I mixed up things with 5.25 drives.

TOS still does poll the status of the WP signal during vertical blank for checking media change. Have to go now, will post a more detailed description later about how this works.

P.S.: For those that sent PM recently, will reply later today. A "bit" busy again :)

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Postby MiggyMog » Wed May 30, 2007 9:53 pm

It would be good to know what the exact difference between each TOS version were & not just the spec of what it should be doing.

I.E. a Memory map/Dissasembly of the ROMS and notes on what section has the code for which function & what is the same/different between each version.

A list of software which patches all know issues/bugs would be good too.

Maybe a competition to see who could re-implement TOS to be faster/smaller, a 32k contest ;-)

(I know better solutions such as magic, etc have long since been around for a while, just thinking out loud...)

Chris do I not need the HD line then? ;-)
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Postby exxos » Wed May 30, 2007 9:58 pm

MiggyMog wrote:Chris do I not need the HD line then? ;-)


nahhh, leave it off and save some wire :D


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