I'm not sure where or when I read this, but I remember developers thought about adding a simple HDD emulation at some point..

Also, the problem with HD support on XT is the slow floppy controller.
With real floppy drives, 500 kbit/s are required to support HD (1,2MB; 1,44MB).
But the XT FDC usually supports 250 kbit/s only. Unless replaced by a high-speed model, of course. For 2,88MB, 1Mbit/s are required.
https://en.m.wikipedia.org/wiki/Floppy-disk_c … ler#Format_data

Some tape streamers used "ISA" cards that were high-speed FDCs with MBit/s transfer rates. Though they usually used a different port address. Some had jumpers, though, which allowed setting port addresses.
With a modified driver.sys or 2m-xbios or driveparm,it may also work.
Re: I'm lost in PC's roots

Last, but not least, XTIDE Universal BIOS can boot via serial. 🙂

Simple HDD emulation would be nice 😀
Challenge with using XTIDE for me is that I have no option rom ability on the mainboard. This is a luggable PC-XT (Sharp PC-7100) with a very small motherboard.
My interest is in making an appropriate fat12 image that can be served from the FF / Gotek.
720K is useful and works well, but I can't seem to get anything else to reliably work.
The FDC does not support 3.5 720K FDD (I have one, plugged it in and it will not read) but whatever the FF / Gotek does seems to be able to present the image.

Theoretically a FAT12 32MB disk should work with the correct geometry, but I can't find a way to make this work.
I'd probably only want 10MB (or 5) anyway due to seek times

Jo22 wrote on 2020-09-02, 04:01:

I'm not sure where or when I read this, but I remember developers thought about adding a simple HDD emulation at some point.. […]
Show full quote

I'm not sure where or when I read this, but I remember developers thought about adding a simple HDD emulation at some point..

Also, the problem with HD support on XT is the slow floppy controller.
With real floppy drives, 500 kbit/s are required to support HD (1,2MB; 1,44MB).
But the XT FDC usually supports 250 kbit/s only. Unless replaced by a high-speed model, of course. For 2,88MB, 1Mbit/s are required.
https://en.m.wikipedia.org/wiki/Floppy-disk_c … ler#Format_data

Some tape streamers used "ISA" cards that were high-speed FDCs with MBit/s transfer rates. Though they usually used a different port address. Some had jumpers, though, which allowed setting port addresses.
With a modified driver.sys or 2m-xbios or driveparm,it may also work.
Re: I'm lost in PC's roots

Last, but not least, XTIDE Universal BIOS can boot via serial. 🙂

4xtx wrote on 2020-09-01, 14:07:

I've tried a few different techniques of writing a raw image and defining an IMG.CFG (with tagging). But I can't seem to get it to work. I'm just greeted with 'not ready' type errors.

Did you specify the 'rate' option? As Jo22 points out, the older double-density floppy controller only supports 250kbps so you have to force it with 'rate = 250'. The 720KB floppy image worked because it uses the same 250kbps transfer rate.
Recently I tried a 2880KB floppy image with FlashFloppy on a 'modern' FDC and I got "general failure reading" errors until I went into the BIOS to configure drive A from the default "1.44MB" to "2.88MB". I guess FlashFloppy is auto-detecting the image size and using a faster transfer rate (1000kbps in this case).
Another option for creating images of any size is dosfstools on Linux, e.g.

1$ truncate -s 8192k bigflop
2$ mkfs.fat -F 12 -v bigflop 
3mkfs.fat 4.1 (2017-01-24)
4bigflop has 64 heads and 32 sectors per track,
5hidden sectors 0x0000;
6logical sector size is 512,
7using 0xf8 media descriptor, with 16384 sectors;
8drive number 0x80;
9filesystem has 2 12-bit FATs and 8 sectors per cluster.
10FAT size is 8 sectors, and provides 2041 clusters.
11There are 8 reserved sectors.
12Root directory contains 512 slots and uses 32 sectors.
13Volume ID is db53cc70, no volume label.

I don't know if that'll work or not, my Gotek is packed away at the moment. You may have to change the media descriptor (-M) as f8 means hard disk, perhaps f0 might work better.

Thanks - something for me to try 😀

I'm also curious as to whether this FDC supported (unofficially) the NEC Quad Density 720K format.

jtchip wrote on 2020-09-08, 01:42:

Did you specify the 'rate' option? As Jo22 points out, the older double-density floppy controller only supports 250kbps so you […]
Show full quote

4xtx wrote on 2020-09-01, 14:07:

I've tried a few different techniques of writing a raw image and defining an IMG.CFG (with tagging). But I can't seem to get it to work. I'm just greeted with 'not ready' type errors.

Did you specify the 'rate' option? As Jo22 points out, the older double-density floppy controller only supports 250kbps so you have to force it with 'rate = 250'. The 720KB floppy image worked because it uses the same 250kbps transfer rate.
Recently I tried a 2880KB floppy image with FlashFloppy on a 'modern' FDC and I got "general failure reading" errors until I went into the BIOS to configure drive A from the default "1.44MB" to "2.88MB". I guess FlashFloppy is auto-detecting the image size and using a faster transfer rate (1000kbps in this case).
Another option for creating images of any size is dosfstools on Linux, e.g.

Copy code to clipboard

1$ truncate -s 8192k bigflop
2$ mkfs.fat -F 12 -v bigflop 
3mkfs.fat 4.1 (2017-01-24)
4bigflop has 64 heads and 32 sectors per track,
5hidden sectors 0x0000;
6logical sector size is 512,
7using 0xf8 media descriptor, with 16384 sectors;
8drive number 0x80;
9filesystem has 2 12-bit FATs and 8 sectors per cluster.
10FAT size is 8 sectors, and provides 2041 clusters.
11There are 8 reserved sectors.
12Root directory contains 512 slots and uses 32 sectors.
13Volume ID is db53cc70, no volume label.

I don't know if that'll work or not, my Gotek is packed away at the moment. You may have to change the media descriptor (-M) as f8 means hard disk, perhaps f0 might work better.

Can any of those oversized floppie images become bootable? Or only usable with custom drivers. Like to make a over 2.88MB floppy image for boot floppy for a no HDD computer.

I’d really love to download one of these over sized images if someone can upload one in a zip?

There is a thread (maybe this one) I read somewhere where someone was able to make like a 6.8mb image was it? Trying to remember.

4xtx wrote on 2020-09-03, 08:32:

Simple HDD emulation would be nice :-) Challenge with using XTIDE for me is that I have no option rom ability on the mainboard. […]
Show full quote

Simple HDD emulation would be nice 😀
Challenge with using XTIDE for me is that I have no option rom ability on the mainboard. This is a luggable PC-XT (Sharp PC-7100) with a very small motherboard.
My interest is in making an appropriate fat12 image that can be served from the FF / Gotek.
720K is useful and works well, but I can't seem to get anything else to reliably work.
The FDC does not support 3.5 720K FDD (I have one, plugged it in and it will not read) but whatever the FF / Gotek does seems to be able to present the image.

Theoretically a FAT12 32MB disk should work with the correct geometry, but I can't find a way to make this work.
I'd probably only want 10MB (or 5) anyway due to seek times

Jo22 wrote on 2020-09-02, 04:01:

I'm not sure where or when I read this, but I remember developers thought about adding a simple HDD emulation at some point.. […]
Show full quote

I'm not sure where or when I read this, but I remember developers thought about adding a simple HDD emulation at some point..

Also, the problem with HD support on XT is the slow floppy controller.
With real floppy drives, 500 kbit/s are required to support HD (1,2MB; 1,44MB).
But the XT FDC usually supports 250 kbit/s only. Unless replaced by a high-speed model, of course. For 2,88MB, 1Mbit/s are required.
https://en.m.wikipedia.org/wiki/Floppy-disk_c … ler#Format_data

Some tape streamers used "ISA" cards that were high-speed FDCs with MBit/s transfer rates. Though they usually used a different port address. Some had jumpers, though, which allowed setting port addresses.
With a modified driver.sys or 2m-xbios or driveparm,it may also work.
Re: I'm lost in PC's roots

Last, but not least, XTIDE Universal BIOS can boot via serial. 🙂

I can confirm the theoretically part from the DOS side, in that I have used emulated floppy images expanded to 32MB both through drvparm meddling on an actual DOS system and on an emulated machine on an Amiga, and DOS 6.22 had no issues continuing to treat it as a floppy. This was not on Gotek though, I'm just saying the other side works.

However... many older games and utils are hard coded to see C: as the hard drive and no other (many you can't even convince to work on D:) so this may cause a wrinkle in the plan if the idea was to have HD installable games on it.

https://hxcmount.atomas.com/

This site has a 32MB "floppy" image. Maybe it will work somehow.

Ok. Tried to make a 2880mb image to work in 1440setting. You have to use both rpm=150 and rate=500 in img.cfg. but then somehow only odd tracks are readable. it presents sector not found.

[2880]
cyls = 80
heads = 2
secs = 36
bps = 512
rpm = 150 if change rpm to 300 and change bios settings to 2.88mb, it works. Rpm 150 for all HD 1.44 floppy drives and biosses.
rate = 500
If you not include RPM and RATE, yo can not see even the first sector or blank disk.

Then i tried:
[2880]
cyls = 160 double the track count and it will work in a normal HD 1.44 bios/controller. Bad thing is, maximum track count is only 255 in flashfloppy. So not so oversized drives possible. I will try to make a 240cyl drive.
heads = 2
step = 1
secs = 18
bps = 512
rpm = 300
rate = 500

Change in the standard 2880 image first sector. location hex18 from 24 to 12. And thats it. You have a 2.88 disk in a normal 1.44 bios/controller.
Do not touch those hacked images with Format, Scandisk or NDD or anything like that. You can SYS and COPY it.

Think i have to make a github account for a bug report. Because everything works with RPM 150 but somehow EVEN tracks are not indexed correctly. I am using standard RAW IMG files, so the sector enumeration has to be produced by FlashFloppy. but I get sector not found on all the EVEN tracks.

Oh wow, I had forgot about this thread 😀

Being limited to double density on the XT I ended up:

- Using a 2.5mb format available in the HxCFloppyEmulator (its the largest DD format)
https://hxc2001.com/docs/gotek-floppy-emulato … s/download.html

- Use NFORMAT driver BIOSPTCH
http://toastytech.com/files/nformat.txt

I found I needed to first boot from a 360K DOS disk with BIOSPTCH driver in config.sys
Then you can switch to any of the other disks on the gotek
I found DOS 6.22 worked best for me and DOS 5 and lower seemed to give me random issues (like writing corrupting files larger than 1KB).
NFormat should work on the lower DOS versions so YMMV
Granted, I didn't do any adjustments of rates - or any troubleshooting.

Regarding "Bootable" images - I was unable to get anything larger than 720K to boot
720K doesnt need NFormat and seemed to work nicely with the older DOS versions
I use this for games or apps that need more of the conventional memory

End result was I had a really slow 2.5mb image working on my XT luggable.
I managed to shrink a Windows 3.0 install down small enough and got it to work - link below
https://www.youtube.com/watch?v=9bJN1SCv448&t=200s

4xtx wrote on 2023-08-04, 23:29:

- Using a 2.5mb format available in the HxCFloppyEmulator (its the largest DD format)
https://hxc2001.com/docs/gotek-floppy-emulato … s/download.html

Is the 2.5MB format actually 2550KiB? That would come from a CHS configuration of 255/2/10. If so, perhaps an alternative to this:

Cyberdyne wrote on 2023-08-02, 09:55:

Tried to make a 2880mb image to work in 1440setting. You have to use both rpm=150 and rate=500 in img.cfg. but then somehow only odd tracks are readable. it presents sector not found.

would be a CHS of 255/2/20 or 5100KiB, leaving it at the default rate=500 for a high-density floppy controller.
I think a higher numbers of sectors per track whilst maintaining a lower rate requires a sector interleave (which is an option in IMG.CFG), though I don't know how to calculate an appropriate number.