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Old 16th May 2023, 4:11 pm   #1
TonyDuell
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Default Getting floppy disk images onto real disks?

As you know I've recently restored a couple of CP/M luggable computers. I also have many other machines with floppy disk drives, 3", 3.5", 5.25" and 8"

The machine I connect to the internet with is a more modern laptop runnng Windows 8.1. Essentially its only interfaces are USB ports.

I would like to be able to :

Download disk images (I assume in .IMD or .TD0 format) and write them to real floppy disks to use in my old machnes

If possble, for the more common filesystems like MS-DOS or CP/M, be able to work with these images on the modern PC at the file level. For example, if I download a CP/M progam as a .COM file I'd like to be able to put it into a disk image of a Philips P2000C disk, then transfer that image to a real floppy and put it in a drive on the Philips machine.

I understand there are designed based on a modern microcontroller that connecct to a USB port and a disk drive. Software on the PC translates between the disk image and the accurately-timed pulses corresponding to flux transitions on the disk. This unit links to a real disk drive, you run the software and it reads/writes a real disk in said disk drive.

Now... I can handle a 'scope. I can handle a logic analyser. I can handle a soldering iron. I can handle an engineer's lathe. I can rebuld and align floppy disk drives. I can program most 8-bit micros along with PERQ microcode, PDP11 mahine code, etc BUT I don't have a clue when it comes to modern PCs, modern microcontrollers or USB ports.

So what I am asking is for people to describe what to do as in :
Buy this microcontroller board
Buy this blank PCB and solder the components given in the BOM to it.
Download this software and install it by doing this.
Connect a standard floppy drive to this connector
Run the software, specify the disk image file and sit back.
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Old 16th May 2023, 4:34 pm   #2
paulsherwin
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Default Re: Getting floppy disk images onto real dsks?

It may be easier to do this with a serial link using something like Kermit at both ends. You will need to obtain or write a userland file system to handle the disk images under Windows or Linux, but that's still easier than writing all the disk control software and building the hardware.

The general procedure would be:

Download disk images onto 'server'
Mount disk image as userland file system so that the OS treats them as physical floppies
Run Kermit in server mode

Get Kermit onto CP/M machine (there are several ways of doing this)
Put Kermit into client mode
Get the individual files

You will need a USB-RS232 adaptor if your 'server' doesn't have a serial port.

Kermit repository: https://www.kermitproject.org/index.html,https://www.kermitproject.org/archive.html

For a start in writing the filesystem, have a look at how Linux implements exFAT: https://github.com/relan/exfat
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Old 16th May 2023, 4:43 pm   #3
TonyDuell
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Default Re: Getting floppy disk images onto real dsks?

I use kermit all the time and have it on most of my machines. And the first thing I bought after buying the modern-ish PC was a USB-RS232 cable.. I'll skip over the fact that the Osborne 1 serial port is horrible, it supports 300 and 1200 baud only.

But surely there are faster and easier ways of doing what I want? It's been suggested that I get a thing called a 'Greaseweazel' but I think there are other similar devices too.
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Old 16th May 2023, 4:44 pm   #4
Outrun_uk
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Default Re: Getting floppy disk images onto real dsks?

Have you looked at a ready built Greaseweazle?

https://www.retropassion.co.uk/product/greaseweazle/

HTH,

Kev
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Old 16th May 2023, 4:52 pm   #5
paulsherwin
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Default Re: Getting floppy disk images onto real disks?

That does look like a useful bit of kit for this sort of job at £21. I don't know how well a standard PC-type drive would handle all the oddball disk formats used by these old CP/M systems though.
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Old 16th May 2023, 5:12 pm   #6
GeoffB17
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Default Re: Getting floppy disk images onto real disks?

I'm doing this sort of thing pretty much regularly, but within certain parameters.

Firstly, I'm mainly using files re Amstrad PCW systems, and CP/M. As far as the images there are concerned this in the .DSK type of images used by the CPC computers.

All this relies on the fact that my main PCW supports 3", 3.5" and 5.25" floppies, and I have an old PC (with a 'proper' FDC) supporting 3.5" and 5.25" floppies and the 22DISK system (which allows reading/writing to a wide range of CP/M formats, the same old PC will also support IMD (and via that TD0). My 'main' working PC (for web links) has a 3.5" floppy drive, and also runs the 'Joyce' PCW emulator, and CP/M-BOX both of which allow fairly full access in/out of DSK image files and thereby into other image types and actual disks. Because of the various forms of floppy access, I don't need to worry about Kermit, or whatever. Sounds like your main bottleneck will be the web/PC where you are restricted by the USB only link?

I've never tried anything with the Greaseweasel, I tend to see that as a solution for reading/writing floppies that cannot be read/written otherwise, and I've never had that problem. Have you looked into one of the Gotek devices, one of these fitted to one of your old machines would allow transfer of files between an image file on a USB stick and a floppy disk on (for example) CP/M systems. I know that various people are using the PCW machines with Goteks, are building images on their web linked PC and then accessing the image on their PCW and transferring indiv files.

Geoff
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Old 16th May 2023, 6:06 pm   #7
Michael Haardt
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Default Re: Getting floppy disk images onto real disks?

Chances are you already have all that's needed at home, and if not, ebay or the junk yard may be helpful to obtain an old PC and old floppy controller along with floppy drives.

This video will tell you lots of the basics:

https://www.youtube.com/watch?v=fRZVlsxSDw0

When it comes to CP/M file system access, 22disk for DOS and cpmtools for Linux will help you.

Really exotic formats need hardware that can record and play back bit streams, but most common CP/M systems do not require that.

Michael
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Old 16th May 2023, 6:13 pm   #8
Phil__G
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Default Re: Getting floppy disk images onto real disks?

I bundle files using PKARC on the PC or ARK11 on CP/M, transfer the one archive file using xmodem, then UNARC on CP/M or PKXARC on the PC to restore the individual files.
Doesnt answer the question but it works well esp for a large number of files, and its quick & easy!

Last edited by Phil__G; 16th May 2023 at 6:35 pm.
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Old 17th May 2023, 5:21 am   #9
TonyDuell
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Default Re: Getting floppy disk images onto real disks?

Is there a major downside to the flux-transition devices of the Greaseweezel type? That's the sort of thing I was considering as it looked to be a universal-ish solution. I do have machines with 'odd' floppy formats (GCR, M2FM, etc) that a PC controller can't handle although getting disk images onto those is not the main thing I want to do at the moment.

More seriously, many PC disk controllers, at least the ones I've worked on, don't handle FM (single density) formats correctly. The original IBM disk controller in the 5150 was double density only and many clones followed suit. I do need single density support for writing classic disk images.

I've looked at the Greaseweazle but have a couple of reservations about the design. The main one is that signals from the floppy drive go straight to pins on the microcontroller. I would have liked some TTL buffers here. The singals to the drive are buffered (7407) but the chip are SMD to harder to replace than (socketed) DIPs. I guess I could add an external board of buffers.

There should be no problem with a 'standard' PC type drive handling oddball formats. The drive is dumb, the signals at the interface connector correspond to flux transitions on the disk. There are restrictions on the time between transition of course. Many of my more recent classic computers use the same types of drives as were used in PCs.

As regards a floppy drive emulator of the Gotek type, that is not really a solution. I have a couple of hundred classic computer here, some of which do not have standard floppy drives in terms of the interface to the controller. So no-go there.
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Old 17th May 2023, 9:50 am   #10
Phil__G
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Default Re: Getting floppy disk images onto real disks?

I've found that often a very old drive is more reliable reading disks created & written itself rather than a disk written on some other machine, aging tolerances, creep, OOA etc so if these old machines have their own disk drives I wouldnt completely dismiss the file transfer method onto the machines own drive
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Old 17th May 2023, 9:58 am   #11
paulsherwin
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Default Re: Getting floppy disk images onto real disks?

I think I agree, particularly if you already have lots of experience with Kermit and serial comms so there's no learning curve.
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Old 17th May 2023, 12:45 pm   #12
JimmyDeath
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Default Re: Getting floppy disk images onto real disks?

Big fan of the Greasweazle. This in combination with the free HxC Floppy Emulator software you can convert between all sorts of formats.

It is my go to when repairing a vintage computer and need to create a real disk to test on it.

Downside is that it does require a degree of familiarity with PCs.

Regards, James
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Old 17th May 2023, 1:04 pm   #13
dominicbeesley
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Default Re: Getting floppy disk images onto real disks?

I keep meaning to get a Greaseweazle - up to now for single or double density discs I use HostFS to connect my BBC Micro to my PC (a "live" filing system) and a program that I've written to format and write images to discs. So far I've managed Atari ST, DOS, Archimedes and BBC Micro Images. I also would like to be able to do other formats like Amiga, C64 etc, HD 1.44 DOS)

I'm not sure however _which_ GreaseWeazle to get V4 seem to be around the £20 mark but V7 looks to be "better" but do I need better? I keep procrastinating and sticking with my very very slow solution!
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Old 17th May 2023, 4:08 pm   #14
TonyDuell
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Default Re: Getting floppy disk images onto real disks?

Quote:
Originally Posted by Phil__G View Post
I've found that often a very old drive is more reliable reading disks created & written itself rather than a disk written on some other machine, aging tolerances, creep, OOA etc so if these old machines have their own disk drives I wouldnt completely dismiss the file transfer method onto the machines own drive
I have 'proper' analogue alignment disks and know how to use them. In general when I restore an old machine, if the drive works I check the alignment -- if it's way out I check any disks that came with the machine to see if they can be read on (a) a correctly aligned drive or (b) the misaligned drive that came with the machine

In the latter case I find a way to copy any disks that came with the machine onto new disks in a properly aligned 'spare' drive.

Then I totally strip the drive (no matter what the condition is), clean the parts, replace bearings if necessary, and do a full alignment. The drives in most of my machines are 'good as new' in most cases.
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Old 22nd May 2023, 7:40 pm   #15
JimmyDeath
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Default Re: Getting floppy disk images onto real disks?

The GreaseWeazle V7 Lightning Plus ( a version that I have made a few of) has some nice features however it is much more expensive than a V4, you are really only going to need it if you intend to copy really high data rate floppies such as the 2.88Mb disk.

The plus versions of the Greasweazle when powered from a 12V PSU will provide 12 and 5 V power via a standard floppy power connector, with the regular version you need to provide your own power.
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Old 23rd May 2023, 12:26 am   #16
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Default Re: Getting floppy disk images onto real disks?

My solution to write the 1.6MB disks required by my GEM S2 is to use an old laptop running Windows XP or 2000 with a real FDD/FDD interface. I then use omniflop and it's special driver for actually writing the disks. In fact any computer with a real floppy interface or one of the rare USB ones that isn't limited to the standard windows/dos formats will work.
If it's only required to write DOS standard capacities then any USB FDD should work, my DELL USB FDD can happily write/read the 720k disks my S330 uses with the specific SDISKW software.
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Old 30th May 2023, 6:32 pm   #17
JohnBHanson
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Default Re: Getting floppy disk images onto real disks?

If you have a matmos/alphatronic PC this can be modified to read a log of disk formats -
please read http://81.98.24.96/alphatronic and look at the high density mods
which is the easiest to get running as it uses 512 byte sectors on 1.44 disk format.


(It can even read ibm-pc floppies).

In addition you can run a drive hosted on a linux box using t-net and xbeaver (which
is available for linux and as a docker for windows). Then connect the matmos PC to the
linux or windows disk with a serial cable.
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Old 1st Jun 2023, 1:55 pm   #18
TonyDuell
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Default Re: Getting floppy disk images onto real disks?

Thanks for that URL.

I do have an Alphatronic computer, although I don't have the floppy drive or controller for it. What I didn't have was any technical information, Now I do.

So while I am unlikely to use this machine as part of my system to transfer disk images to floppies, this comment has helped me in another way.
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