External Disk Drive As Main Drive?

[blackpanther]

Hi all!

I have one of those HcX floppy emulator SD devices and was wondering if someone could help me here. The floppy emulator is connected to the floppy cable on the motherboard, which is causing a slight problem. I also want to use the floppy drive and I'm wondering if its possible to use an external drive and make/use some sort of a switch so I can flick between them when needed. I don't want to swap them round everytime.

Any help would be great. Thanks

[wongck]

I don't have the device so cannot be sure but the theory is this....

Does the ST check and boot from drive B as well?
If it does then get/make adapter for the 34pin FDD cable (HcX cable) that convert it to the 13pin plug (13pin ?) external FDD.
Use the HcX as drive B.
When you want to use drive A, pop a disk in A else boots from HcX.
You need to check if drive B is bootable or not for this theory to work.

[Nyh]

Hi all!

I have one of those HcX floppy emulator SD devices and was wondering if someone could help me here. The floppy emulator is connected to the floppy cable on the motherboard, which is causing a slight problem. I also want to use the floppy drive and I'm wondering if its possible to use an external drive and make/use some sort of a switch so I can flick between them when needed. I don't want to swap them round everytime.

You can use a double toggle switch to swap the drive select A and B signals.

driveselect_mod.png

Hans Wessels

[blackpanther]

I don't have the device so cannot be sure but the theory is this....

Does the ST check and boot from drive B as well?
If it does then get/make adapter for the 34pin FDD cable (HcX cable) that convert it to the 13pin plug (13pin ?) external FDD.
Use the HcX as drive B.
When you want to use drive A, pop a disk in A else boots from HcX.
You need to check if drive B is bootable or not for this theory to work.

Just tried that and it didn't work. Thanks anyway.

Hi all!

I have one of those HcX floppy emulator SD devices and was wondering if someone could help me here. The floppy emulator is connected to the floppy cable on the motherboard, which is causing a slight problem. I also want to use the floppy drive and I'm wondering if its possible to use an external drive and make/use some sort of a switch so I can flick between them when needed. I don't want to swap them round everytime.

You can use a double toggle switch to swap the drive select A and B signals.

driveselect_mod.png

Hans Wessels

To be honest I don't understand that diagram. What do I need to make this work.

Thanks for your help.
Mark

[wongck]

I don't have the device so cannot be sure but the theory is this....

Does the ST check and boot from drive B as well?
If it does then get/make adapter for the 34pin FDD cable (HcX cable) that convert it to the 13pin plug (13pin ?) external FDD.
Use the HcX as drive B.
When you want to use drive A, pop a disk in A else boots from HcX.
You need to check if drive B is bootable or not for this theory to work.

Just tried that and it didn't work. Thanks anyway

Well, I checked my concise atari st reference, and the boot up checks the 1st floppy device unlike DMA devices where it checks all.
So you're correct, it will not work.

Guess your stuck to Nyh method.

[Nyh]

To be honest I don't understand that diagram. What do I need to make this work.

You need one double toggle switch (according to Wikipedia it is called a DPDT http://en.wikipedia.org/wiki/Switch and it normally looks something like this):

You have to cut pin 19 and 20 of the sound chip and solder a wire to it. Each wire goes to two contacts on the switch. One middle contact of the switch is connected to drive A select, the other to drive B select:

floppy switch.png

That is all.

Warning: doing it wrong may well kill your sound chip.

Hans Wessels

[blackpanther]

Right, just found the DPDT Switch which I'll order shortly, all I need to find now is some cables to use. Does it matter what type I go for? I have a couple of spare ST's so If the sound chip does dies then I can use another one. Thanks for your help with this Nyh.

[1024MAK]

Some years ago (okay, many years ago) I moved my Atari STFM to a new desk. One problem was that I could no longer get to the right hand side of the machine so I was stuck when it came to changing disks .
I opened the case and investigated the copper tracks that go to the the external floppy drive connector. Nearby I found some "spare" jumper link positions. I say "spare" because there were no jumper "header" connectors, just the PCB pads where they would go if fitted. However one pair was linked (I forget now if it was a wire link, or a copper track that linked across it).
Anyway, after further investigation I found that on these "spare" jumper link positions both drive select signals are present. So out came my soldering iron and then I had both drive select signals connected through and present on the external floppy drive connector. I made up an adapter lead, made from a 14 way DIN plug and a 34 way IDC socket, so I could connect to the floppy drives using a 34 way ribbon cable. This is still the case on this machine today, where I have a Sony floppy drive fitted. In the past I did have two floppy drives fitted. The only thing to remember is that your floppy drives must have a method of selecting which drive signal they respond to (selection jumper plugs). Also note that a cable from an IBM machine is not suitable if it has a twist in it (at least not without a further modification).
I did make a drawing at the time that I carried out the modification. If I can find it, I will scan it and put the image up.
If your Atari ST has the same arrangement, there is no need to mess with any of pins on any of the chips

[wongck]

I did make a drawing at the time that I carried out the modification. If I can find it, I will scan it and put the image up.

Wow, this is a good hack.
Not sure if anything similar out there.
Would be good to put it on the Wiki if you find that drawing.
Otherwise a short write up may help.

[blackpanther]

Some years ago (okay, many years ago) I moved my Atari STFM to a new desk. One problem was that I could no longer get to the right hand side of the machine so I was stuck when it came to changing disks .
I opened the case and investigated the copper tracks that go to the the external floppy drive connector. Nearby I found some "spare" jumper link positions. I say "spare" because there were no jumper "header" connectors, just the PCB pads where they would go if fitted. However one pair was linked (I forget now if it was a wire link, or a copper track that linked across it).
Anyway, after further investigation I found that on these "spare" jumper link positions both drive select signals are present. So out came my soldering iron and then I had both drive select signals connected through and present on the external floppy drive connector. I made up an adapter lead, made from a 14 way DIN plug and a 34 way IDC socket, so I could connect to the floppy drives using a 34 way ribbon cable. This is still the case on this machine today, where I have a Sony floppy drive fitted. In the past I did have two floppy drives fitted. The only thing to remember is that your floppy drives must have a method of selecting which drive signal they respond to (selection jumper plugs). Also note that a cable from an IBM machine is not suitable if it has a twist in it (at least not without a further modification).
I did make a drawing at the time that I carried out the modification. If I can find it, I will scan it and put the image up.
If your Atari ST has the same arrangement, there is no need to mess with any of pins on any of the chips

Many thanks for posting this, I will open up my computer today and check it out.

Will let you know what I see. Thanks

[blackpanther]

Opened up the computer today but couldn't see anything. I've included a picture as I'm not 100% certain.

[1024MAK]

I have dug out the notes that I made.
Some are, well, not really suitable for publication, so I have redrawn or edited them.
Also included are extracts from the Atari circuit diagrams, plus a picture of an Atari ST circuit board showing link W2. Note that this is not a picture of my machine, but it gives you an idea.
When I have more time I will try to take a picture of my Atari 520 STFM that I modified. For pictures see viewtopic.php?f=15&t=18010#p174681
Please also read the word file that I have included.
In Firefox you can right click on an image, then select "View Image" and you get the full image in a window. Use the back button to return...
Hope this helps

Atari STFM floppy disk drive mod 01 - circuit diagram of mod.jpg

[1024MAK]

And the switch circuit...

[catmando]

To be honest I don't understand that diagram. What do I need to make this work.

You need one double toggle switch (according to Wikipedia it is called a DPDT http://en.wikipedia.org/wiki/Switch and it normally looks something like this):

You have to cut pin 19 and 20 of the sound chip and solder a wire to it. Each wire goes to two contacts on the switch. One middle contact of the switch is connected to drive A select, the other to drive B select:

floppy switch.png

That is all.

Warning: doing it wrong may well kill your sound chip.

Hans Wessels

Other than the cutting of the sound chip pins are there any other tracks to cut? Can you be more explicit with where best to attach the Drive A select and Drive B select wires from the middle pins of the switch

Regards

[DrCoolZic]

I just bought an USB FD emulator (still waiting for it) and this thread is very interesting. My idea is to keep the internal FD and connect the FD emulator using the 14 pins din connector

[PaulB]

If this device is seen as drive B, could you not use the old 'Boot from Drive B' PD program? Stick in in the auto folder on a floppy disk in A, or C (if you have a hard drive). Just a thought.

[SofiST]

The boot self from B will work if using 'Boot from B' program. However, it may be that game will try further load from A - it is actually typical case.
So, I recommend to use switch, with which may swap A and B drives .

[catmando]

If this device is seen as drive B, could you not use the old 'Boot from Drive B' PD program? Stick in in the auto folder on a floppy disk in A, or C (if you have a hard drive). Just a thought.

That is an option but I'd rather just have a switch, also if my original floppy drive is knackered then I have no way of loading the 'Boot from Drive B' program anyway

[catmando]

If anyone else has done the drive switch mod can they post more pictures on here

Thanks in advance

[1024MAK]

In the posts that I made in the thread above I referred to some pictures.
See viewtopic.php?f=15&t=18010#p156635 and viewtopic.php?f=15&t=18010#p156680
Here are the pictures.
This is a C070789-001 REC. C machine.
Because I did not have a circuit diagram at the time, I worked it out by tracing tracks and testing. So when I finished working out the circuit I fitted a white wire link to the L29 position in place of the existing "resister" like "zero ohm resistor" (a type of link that machines can pick and place in to circuit boards).
If I remember correctly I had to cut the small trace between two of the three pads of link W2. I then made a connection to the other pad of link W2.

This modification allows you to use one or two external drives, one as drive A and one as drive B. The internal drive stays as drive A.

This shows the area of the PCB where links L29, L39 and W2 are located.

20 FDC links.jpg

Links L29 and W2

22 FDC links.jpg

46 FDC links.jpg

Link W2

48 FDC link W2.jpg

Link L39

21 Link L39.jpg

[Dal]

I too have a HxC Floppy emulator and my plan is to house it in a case with a >14Pin chassis connector (whatever I can get) running to the 34way HDC header.

I plan to perform the drive switching mod so that I can select whether the HxC is Drive A or Drive B. I just need a couple of things clarified.

1. Pin 8 from the Atari's 14Pin External FDD connector is motor On. is is correct that I will need to wire a switch at my HxC in order to flick this signal between Pin 10 (MOTEA) for Drive 0 and Pin 16 (MOTEB) for Drive 1?

2. From the way the drive switch mod is described, I cut pins 19 and 20 on the sound chip then wire a switch from the chip to swap the signals over. Am I correct in saying that the centre poles of the switch can be connected to to the cut lower leg that is still soldered to the motherboard?

3. Please confirm that the above mod is purely changing the Drive Select for the internal drive (i.e. it doens't swap the signals at the 14Pin External FDD Connector)

[1024MAK]

I too have a HxC Floppy emulator and my plan is to house it in a case with a >14Pin chassis connector (whatever I can get) running to the 34way HDC header.

I plan to perform the drive switching mod so that I can select whether the HxC is Drive A or Drive B. I just need a couple of things clarified.

1. Pin 8 from the Atari's 14Pin External FDD connector is motor On. is is correct that I will need to wire a switch at my HxC in order to flick this signal between Pin 10 (MOTEA) for Drive 0 and Pin 16 (MOTEB) for Drive 1?

I don't think the HxC cares about the motor on signal, as it is meaningless for a motor less solid state device. Quote from the PDF manual "Unlike real floppy disk drive the HxC Floppy Emulator doesn’t use the motor control line. So there are only one jumper to set per virtual disk drive." The manual is at http://hxc2001.free.fr/floppy_drive_emulator/index.html

2. From the way the drive switch mod is described, I cut pins 19 and 20 on the sound chip then wire a switch from the chip to swap the signals over. Am I correct in saying that the centre poles of the switch can be connected to to the cut lower leg that is still soldered to the motherboard?

You don't have to cut the pins of any chip. You only have to cut one small bit of PCB track (the connection between two of the pads of "link" W2) and remove some "links", then solder in some wires - see the diagram at viewtopic.php?f=15&t=18010#p156681
If you cannot see the whole image, if you have Firefox right click and select view image, or download it then view it. See my other entries in this threat for more information and some pictures.

3. Please confirm that the above mod is purely changing the Drive Select for the internal drive (i.e. it doens't swap the signals at the 14Pin External FDD Connector)

Depends on how you do it, you have a choice using my method. You can either have the internal drive switched, or you can have the internal drive stay as drive A (or indeed you can also wire it up so that it is always drive B). If you cut the pins on the sound chip, then the internal drive and the 14 pin external connector will have their drive select lines swapped.

[Dal]

Right - got it! Cheers 1024 - I'll go for the sound chip hack I think as that will suit my needs.

I'll post up a step by step guide once it's done.

[Dal]

I have completed the mod and tested it with my HxC floppy emulator - I can now toggle the HxC to behave as DS0 for loading games or flick the switch back for normal 'legacy' floppy use.

Here's the guide...

Tools:
Screwdriver (D'uh!)
Soldering iron
Solder
Vacuum Pump
Heat Shrink (Optional)
Small electronics-style side cutters
ESD protection
Drill or handheld hobby tool
DPDT switch
some wire
Helping Hands (Optional)
IC extraction tool (if your sound chip is socket mounted)



Open it all up and locate the Yamaha sound chip (U202 on STE):

IMG_0107.jpg

Mine is in a socket however you may not be so lucky - If yours is mounted, then you will need to cut the legs 19 and 20. I have extracted mine using an IC extraction tool and very gently bent the legs so they are sticking out:

IMG_0109.jpg

We now need a good line on the board for DS0 and DS1. These can be found at W301 (DS0) and W300 (DS1) handily located near the sound chip. Flip the board over and remove the solder from pin 1 at each of these points using a vacuum pump:

IMG_0113.jpg

Now sort the switch out. You must use a DPDT switch! I have used Yellow wire for the DS0 line and White for DS1. Solder as shown, the middle pins will be going to W300 and W301 and the right pins will be going to the sound chip. run a piece of heat shrink sleeve down the lines destined for the chip, we will use them later and it serves as a reminder as to what lines go where:

IMG_0118.jpg

Solder the wires coming from the centre pins of the switch to W301 (DS0 - Yellow Wire) and W300 (DS1 - White Wire). Solder from the underside of the board and make sure you cut the excess wire using a small pair of electronics side cutters as flush as possible to the solder joint:

IMG_0121.jpg

Make a hole for your switch:

IMG_0116.jpg

Reassemble the shielding making sure you don't trap the wires anywhere, I used the gap near the serial port for this. You can now reassemble the bottom half of the ST and mount the switch:

IMG_0122.jpg

[Dal]

Now solder the pins on the chip: Pin20=DS0 (Yellow wire) and Pin19=DS1 (White Wire)

IMG_0124.jpg

Apply the heat shrink over the pins, reseat the socket (if required) and route the wires as neat as you care to:

IMG_0129.jpg

Job Done!