PC floppy adaptor for Amiga

[QuasaR]

Ordered and paid
Keep up the good work Stedy

[Stedy]

@Supamax

All units are tested after assembly. I use my A600 and a test disk to verify this.

@Prowler

I've tested the unit using the power connector in my A600 and an A500 with no issues so I am surprised it did not fit your A1200. With some power plugs, the plastic lug moves a little.

Bye,

Ian

[prowler]

Hi All,

Good news! I have completed my initial testing of the adapter, which includes everything it was possible to check without modifying it, and the short answer is: yes it works fine on my box-standard Escom A1200HD!!

Firstly, I apologize for not having done this yesterday, but I arrived home to start my Easter break with a migraine. When I get a bad one I am almost blinded. The first time it happened was shocking. The only way to get through it is to lie down in darkness for a good few hours, after which it was time for sleep anyway.

My Escom A1200 was supplied new by Eyetech with an IDE hard drive, 4-way buffered EIDE interface and external 40-pin IDE interface. All I have done to it since is add an Analogic 8MB memory expansion card, which has proved so unreliable due to dry joints that it has rarely worked and is now, yet again, in an anti-static bag waiting to be fixed. The floppy drive fitted to the Escom is an 880kB Panasonic model JU-257A516P.

My external floppy drive is a Cumana, fitted with an 880kB Citizen OSDC-29C drive.

My Commodore A1200 has an IDE hard drive, '030/40MHz accelerator with FPU and an 880kB Chinon FZ-354 floppy drive.

Only because they have never been used from new, and not with regard to face place, button position, etc., I chose to use 1.4MB Mitsumi D359T5 5V floppy drives to replace, one by one, my Amiga floppy drives for testing the adapter.

To get around the incompatibility between the Amigas' floppy power connectors and the adapter PCB power input header, and to give myself more working room, I decided to use an external PCAT PSU for the 5V supply to the adapter and floppy drives, and a longer data cable to connect the adapter to the Amiga motherboard.

This got everything comfortably away from the keyboard unit instead of balancing on top of it. An adapter was still required for the PCB header, but I found I had just the thing to convert one of the PSU's Molex connectors.

The adapter was supplied with the drive select jumper set to DS1, and, of course, this is the factory setting for PC floppy drives. The changeover to DS0 for the boot drive (A: ) is achieved by a twist in the 34-way cable which reverses lines 10-16. The nRDY source jumper was set to use the supplied clip connected to pin 1 of the Amiga's 23-way floppy drive connector.

Starting with the Escom, I fitted the data cable between the Amiga and adapter, then I mounted the adapter on the PC drive's data connector and attached the power cable from the adapter. The supplied power socket doesn't look quite right, but it's actually a very good fit on the PC floppy drive's power connector. Finally, I hooked up the adapter's power input with the external 5V supply connector.

It is difficult to get to the inside of the Amiga's D-type external floppy drive connector with the RF shield still in place, so instead, because a connection to the Cumana external floppy drive was also required throughout the testing, I decided to source the nRDY signal from the Cumana's pass-through connector on the back of the enclosure.

After checking the connections, I switched on the external PSU and the Amiga, and it booted up normally from the hard disk. One thing straightaway noticeable is the lack of clicking from the new drive. Disks are still automounted on insertion, but without audible evidence of the drive sensing. But then, naturally, the external drive carried on unabated.

In this configuration, the new drive replaces DF0: and the external drive continues as DF1:. The PC floppy drive with adapter is indistinguishable from an Amiga drive in its behaviour. Both internal and external drives continue to automount, read, write and format Amiga and PC-DOS disks, and the internal drive will boot suitably formatted Amiga disks. One successful test completed!

I then gave some thought to trying two disk drives with the addition of a PC floppy drive cable.

The adapter's PC floppy drive connector is a 34-way right-angled socket (i.e., female) mounted underneath the PCB, but a PC floppy drive cable only has sockets - three of them. Thus, to connect the two requires male-to-male adapter, but it is not sufficient to join them end to end (I tried that, and it didn't work!), because the rows also need swapping.

Originally Posted by Stedy

I made a slight error in the PCB design, I forgot to take into account the fact the pins swap rows when the connector to the PC is right angled. To fix it, the connector is mounted upside down.

@Stedy:

Your comment that the pins swap rows when the connector is right-angled didn't sound right to me when I first read it, and now I know why. The true reason for this is that PCB connectors used for both floppy and hard drive data connections are usually plugs (i.e., male), and cables with sockets on either end are used to make the connection between these and the actual drives. If your connector could have been a plug instead, the PCB design would have been correct, and it could have been mounted the right way up.

This would actually be the ideal configuration for use with a PC floppy drive cable to enable the use of two PC floppy drives giving the Amiga "internal" DF0: and DF1: drives without the need for an external drive enclosure or interface.

I cannot test this configuration whilst keeping the adapter intact, as supplied, without making up another adapter. I once made a similar adapter (40-way) for testing whether a pair of IDE hard drives configured as master and slave could be used with a Macintosh IDE hard drive controller (they couldn't!). This would do the trick if I can find it! A lot of work went into that. I must still have it. I will search it out later...

Back to today's testing. Next, I reinstated the Amiga's internal floppy drive and removed the Cumana's drive. I already had this unit disassembled in connection with the External Disk Drive thread ( http://eab.abime.net/showthread.php?t=42585 ).

I connected the adapter between the Cumana's interface board and PC floppy drive. It would certainly no longer fit the enclosure in this configuration, with the Cumana's interface board perpendicular to the drive. However, the test is being conducted merely as proof of concept without regard to the aesthetics, so this is sufficient.

This time, when the Amiga was booted, the only real difference was that the external drive had stopped clicking, whilst the internal drive had resumed. Everything was fine, with the PC floppy drive serving just as well in external configuration as it had internal. Two successful tests completed!

It was at this point that I noticed the clip had come away from the wire protruding from pin 1 of the Cumana's pass-through connector. The second test at least had been conducted with no reference to the nRDY signal.

Leaving the clip disconnected, I repeated the second test and still everything was fine. Then I repeated it again with the adaptor's nRDY source jumper set to 'normal', and everything still worked normally. Neither the provision nor source of nRDY signal appeared to have any influence on the result of the test!

So, I restored the Cumana's Amiga drive to the interface board and once more fitted the PC floppy drive in place of the Amiga's internal floppy, and repeated the first test, both with the adapter's nRDY source jumper set to 'normal' and to use the supplied clip, but without the clip connected. And everything worked perfectly normally in either case!

Finally, I repeated the tests on my Commodore A1200 with the same result. Four successful tests completed! I did get some weird behaviour with the PC floppy drive in internal configuration, but I attributed this to the CrossMAC installation, which I've been using in connection with the A-Max disks thread ( http://eab.abime.net/showthread.php?t=15719 ).

I'm really taken with this adapter, because it ensures that I will still be able to work with Amiga floppy disks using cheap, plentiful and expendable PC floppy drives without modifying them long after the Amiga units have disappeared.

It's a minor niggle that the adapter's power input header is not compatible with the Amigas' floppy drive power connectors. This can be resolved with a pair of cutters when I get my own adapter(s).

I have one more suggestion. This adaptor's floppy power lead is too short to accomodate some of the PC floppy drives I might have chosen for this testing. I would say it should be about 25mm longer to make it "universal".

After this contribution, all feedback would be greatly appreciated - especially comments regarding the value of an alternative adapter featuring a plug instead of a socket to accomodate a floppy drive cable for two drives, and an explanation or even a guess as to why the nRDY signal proved to be so insignificant.

Thanks,

prowler

[prowler]

@Stedy:

I have found the adapter I made for testing a pair of IDE drives configured as master and slave for compliance with a Macintosh IDE hard drive controller. It is a 40-way male-to-male adapter with the rows swapped, and will be perfect for testing the ability of your adapter to provide an interface for two floppy disk drives configured as DS0 and DS1.

I know that the adapter was working when I built it. Although it proved that the Macintosh controller was not compatible with a master/slave pair of drives, the setup worked flawlessly for whichever drive was configured as master.

It only needs a quick continuity check, and it will be ready to go!

prowler

[Calgor]

@prowler

Thanks for the detailed test explanation.

I think the nRDY signal is used for those floppies that the standard ecom mb-floppy drive combo cannot read. Therefore unless you had one of those floppies to test (i.e. a few original game disk floppies which will not boot due to escom floppy drive) along with the nRDY wire connected, then your testing did not check whether it turns the escom floppy drive combo into a proper amiga drive.

Would probably be good to test with the panasonic floppy drive as that is what many escom A1200s (including mine) have included by default.

[prowler]

Hi Calgor,

Thanks for your explanation of that.

However, what my testing was meant to show was that Stedy's adapter could be used to convert a standard PC floppy drive for use as an Amiga floppy drive.

Stedy has already tested the combination in a Commodore A1200, but wanted me to check whether the adapter could be used in the Escom A1200 using the alternative method of sourcing the nRDY signal.

My Escom A1200 is fitted with the Panasonic floppy drive as standard, but my testing replaced this with a Mitsumi PC floppy drive and Stedy's adapter fitted with a clip to connect to the nRDY signal on pin1 of the Amiga's external floppy drive D-type connector.

However, my test appears to show that the nRDY signal is not required!

prowler

[Dexther]

i need one for amiga 1200 end amiga 4000 classic.
Help to buy

[Stedy]

Hi,

As it is the DIY err Easter bank holiday I have been a bit busy

Easy questions first.

@Dexther

http://www.ianstedman.co.uk/Sales/sales.html

Two units cost around 25 euro with postage and packaging.

@Prowler

You have been busy!

Download from Aminet, either State of the Art or Sanity Arte demo. DMS this disks and try them in the Escom A1200. These demos fail to work on an unmodified Escom A1200, so I'm told. That should test out the nRDY fix.

It may be necessary to cut the wirelink on the underside of the motherboard, see how the demos fair first.

I'll tell you know, the 34 way connector for the disk drive does not come out easily. The PCB has plated through holes and a large amount of copper. I damaged a few pads removing mine, when fixing the PCB error by mounting the connector on the underside.

I have not had the time to test two drives. With two adaptors it should work, two drives off one adaptor could not. The adaptor uses nSEL0 from the Amiga, together with nINDEX to create the nRDY signal. The second drive, DF1: can not generate a ready signal, needed by Xcopy and demo disks.

The next batch of PCBs could have a DF1: option. Need to sell the first batch first

I'll make the power lead longer as you suggest.


Thanks for the work done so far, it is appreciated.

@Thread.

A user/install and a build manual should be ready by Monday. I don't ship paper manuals as they add to the postage costs and it helps to save paper.

I shipped 5 orders on Thursday and so far have another 5 orders ready for shipping on Tuesday.

[prowler]

Hi Stedy,

Originally Posted by Stedy

@Prowler

Download from Aminet, either State of the Art or Sanity Arte demo. DMS this disks and try them in the Escom A1200. These demos fail to work on an unmodified Escom A1200, so I'm told. That should test out the nRDY fix.

It may be necessary to cut the wirelink on the underside of the motherboard, see how the demos fair first.

Thanks for the suggestions. I'll do whatever it takes.

Originally Posted by Stedy

I'll tell you know, the 34 way connector for the disk drive does not come out easily. The PCB has plated through holes and a large amount of copper. I damaged a few pads removing mine, when fixing the PCB error by mounting the connector on the underside.

I have not had the time to test two drives. With two adaptors it should work, two drives off one adaptor could not. The adaptor uses nSEL0 from the Amiga, together with nINDEX to create the nRDY signal. The second drive, DF1: can not generate a ready signal, needed by Xcopy and demo disks.

That would seem to make testing the adapter with my back-to-back converter unnecessary. But it might still work with most disks, so I'll probably try it anyway.

Originally Posted by Stedy

The next batch of PCBs could have a DF1: option. Need to sell the first batch first

Am I right in thinking that this option would not be necessary if the PC floppy drive used can be jumpered for DS0 as well as DS1?

Originally Posted by Stedy

I'll make the power lead longer as you suggest.

Thanks.

Originally Posted by Stedy

Thanks for the work done so far, it is appreciated.

You're welcome.

prowler

[prowler]

@Stedy:

I've downloaded *both* State of the Art and (2 part) Sanity Arte DMS demos from Aminet. These disks will check the nRDY feature of the adapter designed for Escom A1200 machines in accordance with the explanation provided above by Calgor.

I have no knowledge of whether my Escom has the wire link underneath the motherboard or not, or indeed whether the modification involves adding the wire or cutting it. If I try the demos in the Panasonic drive, as Calgor suggests, before doing anything else, then I guess I'll find out. If the demos run, then the machine has been modified; if not, then either it is unmodified or else a degrader is required.

If the link exists, I am prepared to remove it, if necessary, to complete the testing, depending on the result of the test with the Panasonic drive.

Easter Sunday is not a good time to try to commandeer the television, so it'll have to wait for a bit.

BTW, I was not suggesting that you replace the 34-way connector on units you have already built to accommodate a PC floppy drive cable, merely that you consider offering this as an option for those who might prefer it. But if, as you say, the adapter will not properly support two drives in this configuration, then this will not be useful anyway.

However, if two adapters can support two PC floppy drives mounted on a PC floppy drive cable, then your proposed DF1: option for the next batch of PCBs will only be required if the cable has no 'twist' *and* the floppy drive used as DF0: cannot be jumpered for DS0 as well as DS1. I seem to be missing something here, because the first batch of adapters already supports overriding the Drive Select signal. What is to be gained by the addition of a DF1: option?

Finally, I'd like to ask another question if I may. Is the Amiga's motherboard floppy connector able to support two *Amiga* floppy drives connected to a PC floppy drive cable as DF0: and DF1:?

I'm sorry for all the questions, but I have a natural curiosity for awkward details like these. It serves me well in my profession (Technical Author).

Thanks,

prowler

[Jope]

Originally Posted by prowler

Finally, I'd like to ask another question if I may. Is the Amiga's motherboard floppy connector able to support two *Amiga* floppy drives connected to a PC floppy drive cable as DF0: and DF1:?

No. In the case of the A1200, you need the ready/motor logic and a hook to the DS1 signal on the CIA or external disk port.

Another in-line PCB could be designed for that. :-D

[prowler]

Originally Posted by Jope

No. In the case of the A1200, you need the ready/motor logic and a hook to the DS1 signal on the CIA or external disk port.

Another in-line PCB could be designed for that. :-D

Hi Jope,

Thanks for the explanation. I guess that's what Stedy means by the implementation of a DF1: option on the next batch of PCBs.

prowler

[Eclipse]

Prowler,
Make sure when you test the Escom machine it's in the state it would have been sold at. If it has the wire going from internal 34 to external 1 then it's been modded.
The best way to test would be to cut the wire off completely.

[Calgor]

Make sure it doesn't have these 2 mods:

AT/Escom FDD connector on motherboard:
http://www.softpres.org/article:hard..._fdd_connector

AT/Escom Panasonic Floppy drive:
http://www.softpres.org/article:hard...u-257a605p_fdd

[extralife]

do not get discouraged if spaceballs, wont boot, im pretty sure that demo wont work well for u if its bootet on an aga machine, arte on the other hand should fly, if the adaptor does its trick, allso u could try out 9 fingers instead of sota, i seem to remember 9 fingers definately wouldnt boot when i had an escom myself, but that it worked on my "real" commodore a1200 and back then i was puzzled why

[prowler]

Originally Posted by Eclipse

Prowler,
Make sure when you test the Escom machine it's in the state it would have been sold at. If it has the wire going from internal 34 to external 1 then it's been modded.
The best way to test would be to cut the wire off completely.

Thanks for the advice, Eclipse. I really wasn't sure what an 'unmodified' machine meant in exact terms. I don't think my machine is modified. I haven't modified it and I bought it new from Eyetech, but I can't be certain that they didn't modify it when they added the external IDE socket and 4-way buffered interface.

Originally Posted by Calgor

Make sure it doesn't have these 2 mods:

AT/Escom FDD connector on motherboard:
http://www.softpres.org/article:hard..._fdd_connector

AT/Escom Panasonic Floppy drive:
http://www.softpres.org/article:hard...u-257a605p_fdd

Thanks for the links, Calgor. I will check the details.

Originally Posted by extralife

do not get discouraged if spaceballs, wont boot, im pretty sure that demo wont work well for u if its bootet on an aga machine, arte on the other hand should fly, if the adaptor does its trick, allso u could try out 9 fingers instead of sota, i seem to remember 9 fingers definately wouldnt boot when i had an escom myself, but that it worked on my "real" commodore a1200 and back then i was puzzled why

Hi Extralife. I don't have the Spaceballs demo. Thanks for confirming that Sanity Arte will work on an AGA machine. If I can get hold of 9 Fingers, then I'll try that out too if you say it works on a C= A1200.

@Eclipse/Calgor/Extralife:

Thank you all for your hints and suggestions, they are really appreciated. I will try to get some further testing done tomorrow, and I'll post the results here.

prowler

[Calgor]

Actually I wouldn't bother verifying the panasonic floppy drive mod I linked to as you could bust your drive if not careful doing that. Theoretically it should be enough to verify the motherboard and that the demo fails to load. Then when using Stedy's adapter with the wire for nRDY it should magically start working. You could also then use Stedy's adapter to load the demo with your other PC floppy drive with which it should also work on the Escom motherboard.

Thanks for taking the time, I myself would be too lazy, but will get the adapter if you can verify it working!

[Stedy]

Hi,

The Escom/AT Amiga 1200 floppy fix connects the nCHNG signal from pin 34 of the PC drive to pin 2 of the Amiga drive connector, the same as my PCB.

If the motherboard has been modified to have pin 34 of the FDD socket connected to pin 1, it should be unaffected by this adaptor, though it would be worth removing the nRDY jumper on my board to avoid possible logic conetention. Will add this to the user manual shortly (WIP).

The Panasonic JU-257A605P drive should work without modifications in this adaptor.

Another bit of software that also requires the nRDY signal is Xcopy. A version is available from Aminet, though it is only in German! My initial prototype design had an issue with nRDY, which I fixed by changing the nRDY logic.

Bye,

Ian

[Yoto]

I´ve been following this thread with some interest for some time now, and wondering if this adapter could be changed to work with the external drive port.
If some kind of adapter DB23 to IDE 34 could be fitted, could it be used externally instead?

[prowler]

Hi All,

Great news: Stedy's adapter works perfectly in an umodified Escom A1200 with the nRDY signal taken from pin1 of the 23-way D-type external drive socket!

I thought I'd get this up in the thread as soon as I'd completed my testing for the benefit of those who will wish to order the adapter now that it's been verified working in this configuration.

I will post the details of my testing here later as soon as I've written them.

Thanks for your patience. I finally got to complete the testing this evening, as my wife didn't wish to see the Chelsea v Liverpool football match!

prowler