Floppy emulator

[SKAN]

@ tnt23

I don't think AmiKit or Vesalia will be interested in manufacturing the emulator, at least not in small quantities.

Go ask ACube Systems then!  :-D

[Eclipse]

@tnt23
I think this is fantastic and will be making one once the schematics are released.
Don't worry about the layout too much as plenty of us have the ability to move the board around.

[timofonic]

What about joining with the HxC floppy emulator? This floppy emulator is designed for supporting more kind of drives and formats, maybe both can collabore in some way too.

I find the TR-DOS support quite interesting. What interface do you use? Do you use a Pentagon or Scorpion? D+ interfaces are compatible with TR-DOS and Beta Disk?

[tnt23]

timofonic wrote:
What about joining with the HxC floppy emulator? This floppy emulator is designed for supporting more kind of drives and formats, maybe both can collabore in some way too.

In fact, my emulator supports PC/DD 720K floppy format, too. Tested it on PC under Linux, and on the Atari 1040ST. I think we've talked with the author of HxC emulator before, don't know if the two projects can be merged together. I'd be happy to share whatever knowledge of floppy matter I have gained so far.

I find the TR-DOS support quite interesting. What interface do you use? Do you use a Pentagon or Scorpion? D+ interfaces are compatible with TR-DOS and Beta Disk?

The BDI interface has been the most popular among Russian ZX Spectrum hobbyists. My own DIY Spectrum and BDI boards are well dead since early 90s. I am waiting for a fellow Scorpion owner to test the emulator on real hardware, I have only tested it under Linux with TR-DOS track format.

[alexh]

I still feel there is a commercial opportunity here.

If the board was made so that it was the same size as a floppy disk drive, with the screw holes in the right places so that it could fit internally, with the controller button in the same place as the eject button it would be great.

[Darrin]

alexh wrote:
I still feel there is a commercial opportunity here.

If the board was made so that it was the same size as a floppy disk drive, with the screw holes in the right places so that it could fit internally, with the controller button in the same place as the eject button it would be great.

Well I'd certainly buy at least one for my A1200T, my A3000 and my A2000.  My A3000 drives definately have problems "remembering" that they actually have a disk inserted at times.

[timofonic]

tnt23 wrote:
In fact, my emulator supports PC/DD 720K floppy format, too. Tested it on PC under Linux, and on the Atari 1040ST. I think we've talked with the author of HxC emulator before, don't know if the two projects can be merged together. I'd be happy to share whatever knowledge of floppy matter I have gained so far.

You can contact with the authors directly over his forums.
http://torlus.com/floppy/forum/viewforum.php?f=2

The good thing is that they are already two people, probably one more could make thigs easier. It could be very nice if you join the HxC Team as providing experience on Amiga and TR-DOS

tnt23 wrote:

I find the TR-DOS support quite interesting. What interface do you use? Do you use a Pentagon or Scorpion? D+ interfaces are compatible with TR-DOS and Beta Disk?

The BDI interface has been the most popular among Russian ZX Spectrum hobbyists. My own DIY Spectrum and BDI boards are well dead since early 90s. I am waiting for a fellow Scorpion owner to test the emulator on real hardware, I have only tested it under Linux with TR-DOS track format.

I know about that interface is quite popular in Russia, I would like to get a Pentagon/Scorpion machine. Not sure if those machines are now produced properly and not know if the D+ is compatible with it.

http://www.worldofspectrum.org/NotThePlusD/

[tnt23]

Fitting the current version of PCB instead of original disk drive could be slightly unusable on big Amigas. Currently it has its controls - LCD and buttons - soldered on the same PCB:
http://milliways.chance.ru/~tnt23/pics/misc/megadrive256_logo.jpg

[tnt23]

@timofonic

You may wish to check http://zx.pk.ru - a definitely one of biggest ZX resources on Russian net. I think it is quite possible to dig through it (in Russian) and to buy unpopulated PCBs or even fully assembled machines to your liking.

Besides, there's a couple of modern ZX Spectrum replica projects, based on Altera DE1 board or standalone. Check this one: http://zx.pk.ru/showthread.php?t=6679

[alexh]

tnt23 wrote:
Fitting the current version of PCB instead of original disk drive could be slightly unusable on big Amigas. Currently it has its controls - LCD and buttons - soldered on the same PCB

I am not a particular fan of the LCD & Multiple buttons idea. Yes it makes it platform independent, but it adds significantly to the overall cost and as you say it makes it difficult to replace "any"[/i] 3.5" floppy drive.

After all you have a powerful computer and a TV, why do you need an LCD?

I prefer the idea of only one button (which would be in the position of the Eject) and using the host machine to select disk images.

How would you do that?

A default boot image (selected on power-up or if the eject is held down for 2 seconds).

The boot image is part binary file, and part interaction with the controller.

The binary file provides the preliminary boot media and the menu system. The controller provides the flash card file listings and a way of selecting a disk image by writing data (back to the controller).

Of course you would need a different "default image" for each target platform, but I am sure they could be knocked together with partners from each scene in 5-10 mins.

Especially if you open-sourced the API (i.e. which tracks do what etc.)

By keeping multi-disk games in folders on the flash card, you could select between disks by simply pressing the eject button for less than 2 seconds to cycle through.

If we could agree a partnership and an API, then I would arrange to get the default boot image (dual-format) coded for the Amiga/ST for an experiment?

By getting rid of the LCD and extra buttons (and support code) the floppy emulator can be reduced in complexity and mass produced for a low price. (And/Or for a high profit ;-))

[JimS]

I saw someone mention the propeller chip earlier in the thread. That chip can generate it's own video with one cog and do the floppy emulation with another. You could even genlock it over the Amiga's own display. I understand the minimig does this with it's cpu.

The other cogs could be used for expansion like reading pc style keyboards and mice or talking to SPI peripherals....

just a notion...

[Jeff_HxC]

I am not a particular fan of the LCD & Multiple buttons idea. Yes it makes it platform independent, but it adds significantly to the overall cost and as you say it makes it difficult to replace "any" 3.5" floppy drive.

Is the price really a problem ? The price difference of an LCD based device and an OSD based device is about 10 euros.

After all you have a powerful computer and a TV, why do you need an LCD?

The device that you are talking about already exist:

http://atariamiga.free.fr/installation_sdiskemul_stf.php
http://atariamiga.free.fr/installation_sdiskemul_amiga600.php
http://atariamiga.free.fr/plateformes.php

But what do you do when you need to plug the emulator on this kind of "computer" ?:
http://www.reflexmusic.de/DSS-1/HxCEmu.htm

Hi Tim, yours device looks great ! :-)
One question: why didn't you use SDRam in this version like in the first version ?

[alexh]

Is the price really a problem? The price difference of an LCD based device and an OSD based device is about 10 euros.

Yes. If we want someone to mass produce them at a price that is inoffensive, and leaves the developer a good margin so they develop something else. Also the LCD's dont have a good MTBF. I know I develop with them.

The device that you are talking about already exist:

I've seen it, but it doesn't work with RGB output and no-one (outside the US) uses anything else do they?

But what do you do when you need to plug the emulator on this kind of "computer" ?

True, that is a case where you need the LCD.

[tnt23]

alexh wrote:

tnt23 wrote:
Fitting the current version of PCB instead of original disk drive could be slightly unusable on big Amigas. Currently it has its controls - LCD and buttons - soldered on the same PCB

I am not a particular fan of the LCD & Multiple buttons idea. Yes it makes it platform independent, but it adds significantly to the overall cost and as you say it makes it difficult to replace "any"[/i] 3.5" floppy drive.

After all you have a powerful computer and a TV, why do you need an LCD?

Frankly speaking, I don't think $10 would add that much to the whole thing. My perception is that for most vintage computing geeks out there it doesn't matter. I have just bought a 16 years old KickStart 2.05 ROM for my A600 for $20,  isn't that kinda weird? :lol:
On the other hand, having some sort of indication of what disk image is in the drive, and what activity is taking place (and I am very keen to know what track is being accessed you see) seems quite nice and friendly. At least with green backlight.

Yes the TV and computer are there, but only Amiga can directly control most of floppy bus signals in the way it makes possible to arrange some hackish exchange protocol between the host and the emulator. Just like it is done with drive ID thing. When a special controller like WD1793 is used to talk to a floppy, there is little to no chance at all to bypass it. Would an Atari ST be able to work through this scheme I wonder.

The boot image is part binary file, and part interaction with the controller.

This can be tricky, althought it would be a nice challenge of its own to hack that interaction. It would have to be completely transparent for the system, use only those floppy bus lines that are there, and (last but not least) must allow write access, too. And definitely would require a new incarnation for another platform.
I am not sure I would undertake this load of development, really :-)

By keeping multi-disk games in folders on the flash card, you could select between disks by simply pressing the eject button for less than 2 seconds to cycle through.

Another thing is that currently it takes emulator 16 seconds to load the selected disk image into its RAM. So there won't be any fast cycling through those images.

By getting rid of the LCD and extra buttons (and support code) the floppy emulator can be reduced in complexity and mass produced for a low price. (And/Or for a high profit ;-))

Well, the support code is already in there, so it won't cut costs as the MCU won't be any cheaper :-) As for any mass production, I doubt there will be any really mass one.

[tnt23]

Jeff_HxC wrote:
Hi Tim, yours device looks great ! :-)
One question: why didn't you use SDRam in this version like in the first version ?

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?

In my old design, an 8Mx8 DRAM chip was used. In fact, the emulator requires 2.5M, so the 4Mx8 or a couple of 4Mx4 DRAMs would also do. Alas, they all are now obsolete. And this 8Mx8 chip would need 3.3 volts so the whole thing ran from 3.3 volts, too, and only at 8MHz.
Dynamic RAM is compact in terms of MCU pins, but rather slow, and has to be constantly refreshed. This all makes accessing it rather slow. Static RAM would probably fit better, but would need more pins, and/or additional latches for its huge address bus.
SDRAM (synchronous DRAM) has to be talked to at speeds that are far beyond the possibilities of simple 8-bit MCU.
So I thought using old 72-pin SIMM modules would be the cheapest way.

[_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!!!!