Support for 5.25 fd-formatted floppy

Support and general discussion.
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Support for 5.25 fd-formatted floppy

Postby altheos » Thu 11 May, 2017 10:59 am

Hello,

I made raw images of some 5.25 fd-formatted (1.6 version) floppies I own. Theses images are readable with wimage but they won't work in PCem, wether or not the BPB is enabled.
pclog says : "BPB reports 2 sides and 512 bytes per sector
bit_rate_300=500
bitcell_period_300=4000
img_load 1 0177D500 sectors=18 tracks=80 sides=2 sector_size=512 hole=1
Seek drive=1 track=0 sectors=18 sector_size=512 sides=2"
I think image is 81 tracks 18 sectors..

OS : MSDOS 5
Machine : AMI 486 Clone, 8 Mb RAM, 486SX 33, no dynamic recompiler, drive B: 5.25 1.2 Mb.

Is there a way to make theses images work in PCem ?
I can provide a sample if needed for testing.

Thanks.
vbdasc
Posts: 25
Joined: Tue 21 Mar, 2017 10:53 am

Re: Support for 5.25 fd-formatted floppy

Postby vbdasc » Thu 11 May, 2017 11:35 am

I don't think any real 5.25 inch HD floppies can reliably support 18 sectors (512 bytes each) per track. Unless they're modded to spin at less than the standard 360rpm, that is.

By the way, what's exactly the size of these images?

altheos wrote:(1.6 version) floppies


What exactly does this mean?
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Re: Support for 5.25 fd-formatted floppy

Postby altheos » Thu 11 May, 2017 11:47 am

Fd-format was : " A DOS tool written in Pascal by Christoph H. Hochstätter that allows users to format floppy disks to a higher than usual density, enabling the user to store up to 300 kilobytes more data on a normal high density 3.5" floppy disk" (wikipedia). It is not related with linux's fdformat command.
I used to use it on my 286 machine with 5.25 floppy back in 90s.
vbdasc
Posts: 25
Joined: Tue 21 Mar, 2017 10:53 am

Re: Support for 5.25 fd-formatted floppy

Postby vbdasc » Thu 11 May, 2017 12:03 pm

altheos wrote:Fd-format was : " A DOS tool written in Pascal by Christoph H. Hochstätter that allows users to format floppy disks to a higher than usual density, enabling the user to store up to 300 kilobytes more data on a normal high density 3.5" floppy disk" (wikipedia). It is not related with linux's fdformat command.
I used to use it on my 286 machine with 5.25 floppy back in 90s.


Okay, now how about the size of the image?
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Re: Support for 5.25 fd-formatted floppy

Postby altheos » Thu 11 May, 2017 12:10 pm

Winimage reports : 1.494.528 bytes in 2919 clusters for a 5.25 HD floppy. I will check on real hardware to report sectors/tracks
Battler
Posts: 793
Joined: Sun 06 Jul, 2014 7:05 pm

Re: Support for 5.25 fd-formatted floppy

Postby Battler » Thu 11 May, 2017 2:24 pm

You don't need to. Just look under image information in WinImage. In fact, we can safely assume it's two sides and with 512-byte sectors, so all we need to know is sectors per track and the image's size in bytes, then the rest can be calculated.
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Re: Support for 5.25 fd-formatted floppy

Postby altheos » Thu 11 May, 2017 5:37 pm

OK. The specs on real hardware are : 82 tracks, 18 sectors/tracks, 2 sides, 512 bytes. Total space : 1494528 bytes. Total : 1511424 bytes. I could not find tracks and sectors details in winimage
It's the max that fdformat can do on 5.25 floppy.
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Re: Support for 5.25 fd-formatted floppy

Postby altheos » Mon 15 May, 2017 8:52 am

Tried other floppy format (3.5 HD and 5.25 DD) and interestingly PCem read the TOC but doing anything with floppy result in garbage.
Physical characteristics of disks are : 3.5 HD floppy = 82 tracks, 21 sectors/tracks, 2 sides, 1.745.408 bytes and 5.25 DD floppy = 82 tracks, 10 sectors/tracks, 2 sides, 832.512 bytes.
Logs :
Loading as ima
BPB reports 2 sides and 512 bytes per sector
bit_rate_300=500
bitcell_period_300=4000
img_load 0 0177D500 sectors=21 tracks=80 sides=2 sector_size=512 hole=1
Seek drive=0 track=0 sectors=21 sector_size=512 sides=2
Disk seeked to track 0
Seek drive=0 track=4 sectors=21 sector_size=512 sides=2
Disk seeked to track 4

Loading as ima
BPB reports 2 sides and 512 bytes per sector
bit_rate_300=250
bitcell_period_300=8000
img_load 1 0177D500 sectors=9 tracks=80 sides=2 sector_size=512 hole=0
Seek drive=1 track=0 sectors=9 sector_size=512 sides=2
Disk seeked to track 0
Seek drive=1 track=0 sectors=9 sector_size=512 sides=2
Disk seeked to track 0
altheos
Posts: 37
Joined: Wed 24 Feb, 2016 7:27 pm

Re: Support for 5.25 fd-formatted floppy

Postby altheos » Fri 19 May, 2017 12:47 pm

I found a workaround : put my 5.25 floppy disk in a 3.5 drive and it works. Not really exact emulation but i can live with that.

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