Floppy emulator

[_ThEcRoW]

Hello Tim, i want to know if you will ever do those floppy emulators at a price, because i'm not good at electronic skills. Have you done it already?
It's a good and interesting project and i'm following it since i first hear of it.
Thanks in advance!!!!

[Jeff_HxC]

Hello Jeff, glad to see ya  Thanks! My congratulations on your completion of a standalone emulator. It looks pretty fast, do you use specially prepared MFM files to speed things up?

Yes, Original file image are converted to a prepared MFM file. The emulator simply read MFM data directly from this file and send it through the Pic EUSART.
 

[easy_john]

I act in a role of a tester of the floppy emulator 'megadrive' from tnt23.
I confirm, that work goes by accelerated tempo, for last month tnt23 has let out about seven versions of updatings, and some times it was necessary to solder some contacts.
By the current moment the basic modes work on a1200, and correctly works with dos diskettes. Gradually the same comes to life the rest.

That represents megadrive at me (tnt23 will probably do on another, it that has made with it)

On controller board: floppy and power connector, SD cardreader, IDE connector (megadrive is able to read images and from SD, and from IDE  hard drives, or CF on CF2IDE adapter), speaker (emulates a sound of the disk drive)

I have transferred the display and buttons on a separate board, for convenience of management. It looks here so:

As on pad I plan to transfer led of ide/sd/floppy activity.

Possibly later I shall place it inside of any old gamepad or something similar.

The board is located inside of the case, pad remains outside, it is not required changes of the case.

For storage or movemen pad it is easily disconnected, the cable can be hidden inside of the case.


Screenshots during work:

[alenppc]

 I have just finished reading this whole thread... I must admit that this project looks awesome. :-)

I have a few questions though.

1) How do you interface the card with different computers? For instance, the connector pinout of the floppy interface is slightly different on the PC and Amiga for example. How does the card know which kind of a computer it is connected to? Is this all selectable through software, or is there a jumper of some kind?

2) For the buffer, I guess you just use a 4 MB simm, right? what if you haven't got a 4 MB simm, would the interface work with (e.g.) an 8 MB one? Also are there any limitations on the type of SIMMs you can use (FPM/EDO/Buffered...)?


3) A question for alexh: you mentioned a "default boot image (dual-format) coded for the Amiga/ST". How can you create a single image that is bootable on both Amiga and the ST?? :-? That doesn't sound right...

[easy_john]

I have a few questions though.
1) How do you interface the card with different computers? For instance, the connector pinout of the floppy interface is slightly different on the PC and Amiga for example. How does the card know which kind of a computer it is connected to? Is this all selectable through software, or is there a jumper of some kind?

Connector on PC and Amiga identical, the difference in signals was processed in software.
At this time there is a menu item to switch. but it may changed many times to the release.

2) For the buffer, I guess you just use a 4 MB simm, right? what if you haven't got a 4 MB simm, would the interface work with (e.g.) an 8 MB one? Also are there any limitations on the type of SIMMs you can use (FPM/EDO/Buffered...)?
At this time Megadrive use only about 2.5 MB ram, so any simm that more 3MB are okay.

[tnt23]

@easy_john

Thanks for review :-)

@alenppc

Both interfaces are almost similar, except for RDY and DISKCHANGE signals. RDY (internal bus pin 34) is used in Amiga mostly to detect drive type on startup, whereas for PC it is an indication of disk presence in the drive. PC also seems to pay no attention to DISKCHANGE, or it depends on the FDC. Currently host type (PC/Amiga) is selectable through the Settings menu.
There are also minor diffrences in using SELx and MTR lines.

As for memory modules, almost any 4M or 8M SIMM should work. There should be no difference if it is EDO or FPM. I have a bunch of 72pin modules, all of them seem to work.

[Xenepp]

Wow, this might be the answer Super Magicom owners have been looking for since 1992

Great work, can't wait to get hold of one of these.

 -Joel

[rkauer]

 @TNT23:

 Superb work 'till now.

 For the people willing to use it in big box Amigas, it's a simple matter of move the display and buttons to a front panel, maybe in a 5 1/4" fascia.

 I want the hardware as is it now!

[easy_john]

For the people willing to use it in big box Amigas, it's a simple matter of move the display and buttons to a front panel, maybe in a 5 1/4" fascia.

Now it is a problem.
The height of the display is more than height 5.25 drive bay.
Now we argue with tnt23 on how should look his "megadrive".
It suggests to do its built in, and to do holes in Amiga case.
I approve, that it is necessary to do so, that the device would be possible to add and to remove simply, without changes of the case, i.e. to be only used floppy slot (for card reader) and eject button hole (to connect external pad).

[alexh]

Xenepp wrote:
Wow, this might be the answer Super Magicom owners have been looking for since 1992

Surely SuperMagicom owners use the parallel port interface? I know I did.

[alexh]

alenppc wrote:
3) A question for alexh: you mentioned a "default boot image (dual-format) coded for the Amiga/ST". How can you create a single image that is bootable on both Amiga and the ST?? :-? That doesn't sound right...

Where have you been for the last 18 years?

There were 10's of games with DualFormat disks and 100's of Magazine coverdisks.

Lethal Xcess,
Monster Business,
Starglider 2,
Stunt Car Racer,
Bionic Commando,
3D-Pool,
Carrier Command,
Indiana Jones,
Zero Magazine,
ST-Amiga Format Magazine
"The One For 16-bit games" Magazine
etc. etc.

Rick Dangerous II is Tri-Format supporting Atari-ST, Amiga and PC on one disk!

The technique I *think* was discovered and utilised mainly by "Rob Northen Computing" but it may have been simultaneously developed elsewhere.

[alenppc]

alexh wrote:

Where have you been for the last 18 years?

There were 10's of games with DualFormat disks and 100's of Magazine coverdisks.

Lethal Xcess,
Monster Business,
Starglider 2,
Stunt Car Racer,
Bionic Commando,
3D-Pool,
Carrier Command,
Indiana Jones,
Zero Magazine,
ST-Amiga Format Magazine
"The One For 16-bit games" Magazine
etc. etc.

Rick Dangerous II is Tri-Format supporting Atari-ST, Amiga and PC on one disk!

The technique I *think* was discovered and utilised mainly by "Rob Northen Computing" but it may have been simultaneously developed elsewhere.

I admit I never ever heard of this feature before. :-o But how is it possible? The file systems are completely incompatible, so how do you create a multi-filesystem disk?? And if you use a non-dos encoding for the Amiga, then surely the bootblock won't be read by any other machine... non-dos disks are not supported on MS-DOS and I would suspect Atari either (but not sure about this one).

[jj]

Small games that three different versions fit on one disk.  They would be non-dos disks so the filesystem does not matter as they would be cutom and handled by the bootloader

[alexh]

You are thinking at the data block level. I am not 100% sure but I *think* it is done at the MFM level

[alenppc]

JJ wrote:
Small games that three different versions fit on one disk.  They would be non-dos disks so the filesystem does not matter as they would be cutom and handled by the bootloader

As I wrote above "And if you use a non-dos encoding for the Amiga, then surely the bootblock won't be read by any other machine... non-dos disks are not supported on MS-DOS and I would suspect Atari either (but not sure about this one)."  ;-)

Well, I will definitely have to look into this...

[Jeff_HxC]

Hello Jeff, glad to see ya Thanks! My congratulations on your completion of a standalone emulator. It looks pretty fast, do you use specially prepared MFM files to speed things up?

Yes, Original file image are converted to a prepared MFM file. The emulator simply read MFM data directly from this file and send it through the Pic EUSART.

If you want, i can add a new output file format in the software for your emulator !
The only thing to do is specify it! :-)