3.5" and 5.25" floppy drives

[+mizapf]

Two questions:

 

1. Are there 40-track 3.5" drives? All drives I found specify 80 tracks.

 

I know there are HD disk media (with two holes) versus DD disk media (with one hole), but both are using the same track count of 80. I actually have a 3.5" drive with 80 tracks in my PEB which I use to boot my Geneve.

 

2. Has anyone ever used a 80-track 5.25" drive with the TI/Geneve?

 

80-track 5.25" drives were the latest class of minifloppy drives used in PCs; they were also called 5.25" HD drives (for disk capacities of 1.2 MiB).

 

I just learned that the 5.25" drives have an interesting property: they are rotating at a higher speed (360 rpm instead of the standard 300 rpm). I would expect problems with DSRs that expect 300 rpm.

 

The background of my question is that for the next evolution step of MAME/MESS I have to take care whether the attached floppy drive is compatible with the inserted disk image. For instance, it does not make sense to use a 5.25 drive and try to read 80-track images if this combination is not realistic; this must cause a read error.

 

[Omega-TI]

Two questions:

 

2. Has anyone ever used a 80-track 5.25" drive with the TI/Geneve?

 

 

 

There is a nice project showing how it's done here:

 

http://www.mainbyte.com/ti99/2drives/2drives.html

[jens-eike]

1. Yes, some TI-users had 40-track 3.5" drives (Epson), they were especially popular in the Wiesbaden group.

2. Yes, there were several mods to disk controllers, [url=http://www.mainbyte.com/ti99/store/EPROMS.html

lists EPROM upgrades for the TI and Myarc FDC. You already know about the Geneve using 1.44MB floppies.

Btw, does it matter if your image has 1440 sectors as DS/DD40 or DS/SD80 (TI controller modded) or even SS/DD80 as long as the controller manages to find the correct sectors?

Edited February 1, 2014 by jens-eike

[Omega-TI]

** MESS REMOVED **

See message 10 for properly formatted (.pdf) document.

Edited February 2, 2014 by --- Ω ---

[+mizapf]

1. Yes, some TI-users had 40-track 3.5" drives (Epson), they were especially popular in the Wiesbaden group.

 

Do you happen to remember the drive name? In MAME/MESS we currently do not have any 40-track 3.5" drive; this will have to be added.

 

 

2. Yes, there were several mods to disk controllers, [url=http://www.mainbyte.com/ti99/store/EPROMS.html

lists EPROM upgrades for the TI and Myarc FDC. You already know about the Geneve using 1.44MB floppies.

Btw, does it matter if your image has 1440 sectors as DS/DD40 or DS/SD80 (TI controller modded) or even SS/DD80 as long as the controller manages to find the correct sectors?

 

DD is MFM, SD is FM recording, so this definitly matters for the controller. Also, for higher densities (like 36 sectors/track), magnetic cells are half as long, so transfer rates are doubled.

 

If the rotating speed were the same I would not have bothered, but when I saw that the 5.25" HD drives are rotating at higher speed I started to wonder whether anyone is known to successfully attach such a drive. I believe most people directly went for the 3.5" drives and did not even try a 5.25" HD drive.

 

Background:

 

I'm currently updating the floppy support for the TI systems in MESS to catch up with the latest emulation features (and, in particular, to allow legacy code to become obsolete at last). Indeed, disk images are now read and converted to magnetic flux sequences in memory, and the emulated controllers really need to interpret FM or MFM recordings.

[Gazoo]

Two questions:

 

1. Are there 40-track 3.5" drives? All drives I found specify 80 tracks.

 

I know there are HD disk media (with two holes) versus DD disk media (with one hole), but both are using the same track count of 80. I actually have a 3.5" drive with 80 tracks in my PEB which I use to boot my Geneve.

 

2. Has anyone ever used a 80-track 5.25" drive with the TI/Geneve?

 

80-track 5.25" drives were the latest class of minifloppy drives used in PCs; they were also called 5.25" HD drives (for disk capacities of 1.2 MiB).

 

I just learned that the 5.25" drives have an interesting property: they are rotating at a higher speed (360 rpm instead of the standard 300 rpm). I would expect problems with DSRs that expect 300 rpm.

 

The background of my question is that for the next evolution step of MAME/MESS I have to take care whether the attached floppy drive is compatible with the inserted disk image. For instance, it does not make sense to use a 5.25 drive and try to read 80-track images if this combination is not realistic; this must cause a read error.

 

 

1. Yes, but they are rare.

 

2. Yes, there were 5.25" 80 track double density drives produced. I have several of these. I used them for a while but abandoned them because a 40 track disk written to by them by double stepping became unreadable in a 40 track drive.

 

Gazoo

[+Ksarul]

Any of the 5.25 drives listed above as QD (720K formatted/1MB unformatted) spins at 300 RPM and will work with any TI (or Geneve) configured to run 80-track drives. I have something like half a dozen TEAC FD-55F drives. On the Epson 40-track 3.5 drives--I have two of them squirreled away, bought as part of the same group buy that the Wiesbaden group arranged. I think they were called SMD-165s, if the Epson PX-10 reference I found is correct. Just look at the diagram on the page for the drive reference.

 

http://fjkraan.home.xs4all.nl/comp/px8/pf10/

 

Actually, that led me to look even further--there are six Epson 3.5 drives that used the 40-track format. Go here for the chart:

 

ftp://ftp.epson.com/desktop/OEMFDD.TXT

 

The ones bought by the Wiesbaden group were either SMD-120 or SMD-160 drives (I'd have to pull one of mine out of storage to verify exactly which one it was).

Edited February 2, 2014 by Ksarul

[jens-eike]

My 3.5" is an EPSON SMD-120.

Datasheet:

 

http://www.sharpmz.org/download/floppy_smd100_specifications.pdf

Edited February 2, 2014 by jens-eike

[+mizapf]

Hello Jens-Eike,

 

great, thanks for the specs!

 

I just saw that in MESS we actually have the Epson SMD-165 with 40 tracks at 3.5", just had to scroll down the file to the end. :-)

 

@Ksarul: Indeed, I just noticed that there is also a class "floppy_525_qd" with 80 tracks and 300 rpm. The 360 rpm apply to the HD drives only.

 

I hope that once I'll have switched to the new floppy system I can finally do what I've had in mind for so long: Adding drive sounds! I recorded some samples of my 3.5" and 5.25" drives, and according to the other devs it should be pretty easy.

Edited February 2, 2014 by mizapf

[Omega-TI]

Oka, here is a LEGIBLE format (.pdf) of the drives list.....

 

P-Box Compatible Disk Drives.pdf

[eck]

I believe, that there was at minimum one stand alone 3.5 40 tracks drive for MSX1 users to buy. But I may be mistaken.