PC floppy adaptor for Amiga

[jaycee]

Hi Ian,
Is there any reason the 74LS38 has to be used over the 74LS00 ? I guess the open collector outputs are required?

Also, a bit off topic - how good is that Ant16 logic analyzer and how much does it cost ?

[Stedy]

@Jaycee

The open collector 74LS38 NAND gate is essential. Without it the FDD interface does not work. My very first build of the logic for the new design had the tri-state logic wrong, it locked up the FDD bus. Problem was easily found and fixed.

The ANT16 logic analyser has been discontinued, replaced by the ANT18. You can order it from here: http://www.easysync-ltd.com/category...struments.html

It's fine for what I have used it for. The trigger options are adequate. Worked fine on the FDD interface and also worked well when tested on a BT656 video stream. The grabber clips are worth ordering, saves making up your own leads.

@thread
Time had been limited recently and Arduino boards are a lot of fun to play with
Still experimenting with the HD logic interface, had to re-read some documents on the Amiga/PC FDD interface.

Have been giving some consideration to making another batch of the original, DD only design, for two reasons, cost and they can be used outside for devices other than the Amiga. The new design will cost around £18, a tweaked original design would be £11.

I have had some interest in adaptor PCBs for various keyboards and synthesizers to replace Shugart FDDs (like the Amiga).

I am still going ahead with the V3 design, which will have HD support and be capable of being made into an external FDD drive. Would there be a demand for the original design?

Ian

[prowler]

Originally Posted by Stedy

@thread
Time had been limited recently and Arduino boards are a lot of fun to play with
Still experimenting with the HD logic interface, had to re-read some documents on the Amiga/PC FDD interface.

Have been giving some consideration to making another batch of the original, DD only design, for two reasons, cost and they can be used outside for devices other than the Amiga. The new design will cost around £18, a tweaked original design would be £11.

I have had some interest in adaptor PCBs for various keyboards and synthesizers to replace Shugart FDDs (like the Amiga).

I am still going ahead with the V3 design, which will have HD support and be capable of being made into an external FDD drive. Would there be a demand for the original design?

Ian

Hi Ian,

I would certainly be interested in another couple of the original adapters if you decide to produce some more.

In that event, I would still wish to acquire some of your planned future adapters with external FDD compatibility and/or HD support.

I'm really looking forward to see what you can achieve with those!

[ChrisUnionNJ]

Originally Posted by Stedy

@Jaycee

The open collector 74LS38 NAND gate is essential. Without it the FDD interface does not work. My very first build of the logic for the new design had the tri-state logic wrong, it locked up the FDD bus. Problem was easily found and fixed.

The ANT16 logic analyser has been discontinued, replaced by the ANT18. You can order it from here: http://www.easysync-ltd.com/category...struments.html

It's fine for what I have used it for. The trigger options are adequate. Worked fine on the FDD interface and also worked well when tested on a BT656 video stream. The grabber clips are worth ordering, saves making up your own leads.

@thread
Time had been limited recently and Arduino boards are a lot of fun to play with
Still experimenting with the HD logic interface, had to re-read some documents on the Amiga/PC FDD interface.

Have been giving some consideration to making another batch of the original, DD only design, for two reasons, cost and they can be used outside for devices other than the Amiga. The new design will cost around £18, a tweaked original design would be £11.

I have had some interest in adaptor PCBs for various keyboards and synthesizers to replace Shugart FDDs (like the Amiga).

I am still going ahead with the V3 design, which will have HD support and be capable of being made into an external FDD drive. Would there be a demand for the original design?

Ian

I sure would be interested!!

Chris

Hi, this is my first post in this forum and I'm really amazed at the amount of technical info you can get from here. I have an ESCOM Amiga 1200 that I have purchased from eBay lately. At the beginning I thought there is a problem with DF0: as XCOPY is not working and sometimes I get errors on disks on other disk copying/testing programs. I purchased a new drive from Amiga Kit which is basically a modified PC drive and yet the same problem!! After reading this thread I realized that the problem is within ESCOM Amiga 1200.
I would like to purchase the modifier circuit board (assembled) to test on my Amiga. Please do let me know how to get in contact with you to arrange for this matter. May be I can help in some sort of actual testing if you need, my drive is Panasonic JU-257A605P .. still I will pay for the board of course.
I just also wonder if the modifications on:
http://www.softpres.org/article:hard:fixing_the_amiga_technologies_a1200_fdd_connector
and
http://www.softpres.org/article:hard:modifying_the_pansonic_ju-257a605p_fdd

would be worthy to do? I would appreciate any feedback .. thank you

[orange]

you should use this fix:
http://aminet.net/package/docs/hard/Floppy_fix

well its probably the same thing but aminet was first!

[Stedy]

Hi,

When I have finished my current testing a progress report will be made.

Answering some of the queries raised recently:

@Kattan

My design was influenced by the software preservation Escom floppy fix, most notably with the clip on solution to the nREADY signal.
If you are competent with a soldering iron, it should fix Escom/AT A1200s. I provided an adaptor PCB for those who did not want to tackle the fix themselves.

@Chrisunionnj

I'll add you to the list of interested parties in the new design.

Bye,

Ian

Thank you for the quick reply Ian, you have encouraged me to do the soldering myself and .. it worked! Both the A1200 mobo and the Panasonic drive were modified and now OK even with XCOPY. I'm still interested in your design, would buy one for sure.

I have another AmiKit compatible drive and it is still under warranty. No labels other than those of AmiKit and a Warranty seal. The drive works fine on both the Amiga Technologies computer and the older Commodore A1200 even with XCopy. I decided to give it a look and to my surprise underneath was a Sony MPF920, exactly like the one in one of the PCs I use. However, the mod AmiKit did is different from that posted on the web for both MPF920 and MPF920-E. They use a signal diode between pin 34 and pin 4 instead of connecting pin 34 directly to one of the board chips. I will have one of those signal diodes soon but I couldn't just wait and decided to try the posted mod for MPF920 (two wires and a cut). The drive worked fine but not with XCOPY!! I guess AmiKit did the job better. Figuring out what they did exactly is a bit hard as the area is covered with plastic glue (the glue gun type). I'm still trying to figure out how they did it and will post my findings here.

[orange]

in the past I used diode between 34 and 12(10), like this:
http://www.amiga.org/gallery/index.php?n=2181

had no problems.

[Mr B]

I want a external, HD/DD capable thing. Preferably autoswitching by means of the hole in the corner of the floppy, but as that is unlikely, a switch will suffice.

Will try and keep tabs on this thread as to not miss out when it's out of development.
B!

[orange]

hm, about those PC drives, do they solve the coercivity problem when using HD diskettes as DD?

perhaps there should be another hack to make them use stronger field with "DD"?

[Jope]

The hack is to let the drive detect the HD disk with it's HD detection switch, but let the computer send the data as if it were a DD disk.

Should work as it is, as the PC drives don't send a special bit stream to the Amiga when a HD disk is installed. Naturally Stedy's adapter may or may not do something else.

Disks written like this probably can't be updated by a DD drive very realiably.

[Stedy]

Hi,

It has been a long time since my last posting in this thread. Work has a knack of getting in the way of the more interesting things in life

An updated double density only, the V2 design, will be available for sale later this week, just putting the final few through testing. The price per unit will be £13.50 + P&P. Test details and pictures are here:

http://eab.abime.net/showpost.php?p=...&postcount=100

The new design works as an external drive, the drawing of the cable wiring will be available with the updated user manual, which is being worked on.

Ian

[lesta_smsc]

Just a quick message to say well done Stedy! I would seriously consider this, but I still have a couple of external Amiga drives to keep me going should I ever need them. Keep up the good work!

[rockape]

Hi,

I remember when I bought my Catweasel for my Amiga1200 EyeTech Tower years ago that the info on the Catweasel said NOT to use Mitsumi drives because they where designed for installing software only.

I`ll dig up the Catweasel docs to confirm.

Regards, Michael

aka rockape

[prowler]

I've been using various Mitsumi units with my Amigas via Stedy's floppy drive adapters ever since the adapters were available with no problems whatsoever.

[Jope]

The reason they said that is because many mitsumi drives are made out of sheet metal, which makes them prone to going out of alignment.

You should use a drive with a cast aluminium body if you intend to write something.

[prowler]

Yes that's understandable. I can confirm that all my Mitsumi units are of the sheet metal type, but for data recovery I have found it useful to have some drives with slightly misaligned heads.

[delshay]

Originally Posted by Stedy

Hello,

I've finally started assembly.

Thought you might like a few pictures of the first assembled unit. Sorry if a little blurry, used my camera phone.

The assembled PCB.



Underside of PCB.



Connected to a disk drive.



There are two sets of jumpers.
The first changes the drive select signal on the PC drive to allow DS0 or DS1, this caters for drives/cable settings.

The second jumper allows the nREADY signal to either be output via pin 34 to the Amiga or using a cable connected to the 23 pin d-type for Escom A1200s.
The user manual, which I have yet to write will detail this.

A support page will go online soon. Schematics, PCB layout and bill of materials will be available.

Pricing and orders

I want to get a number of units assembled before the new ordering system is put online, please bear with me.

An assembled unit is 9 UKP
A kit of parts is 6.50 UKP
A PCB is 3.50 UKP

Currently have the parts to make 50 units in stock. Have had expressions of interest covering 26 units so far, so there are units available for ordering.

Dinner time

I have this floppy drive modified internally so you can plug this direct into amiga floppy port. Probably the best drive I have used for read/writing floppy disk probably down to better heads or 100% perfect head alignment.

[delshay]

Mitsumi FA402A or FA404M can't remember which one I modified but I do have both types.

Both type of drive should work amiga "with modification" but I can only confirm one is working.

Both drive support flash cards but you will need a USB connection for this to work (not tested)

This drive may also work in HD mode with a converter,it was detected here on my system showing 1.44Mb but did not format,so a little more work is needed to get it fully working at 1.44Mb mode,but I use PFS so will show 1.76Mb if I remember correctly.