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 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 ???
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?
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....
exxos wrote:I am still slightly confused about the media change, maybe someone can remind me of what the actual issues are?
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.
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).
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.
I dont know about the WP poll thing, it does not sound like its part of the media change system.
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.
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!
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