Sony OA-D3XV Series

Sony OA-D3XV Series

General Info
Release Year	1981
Manufacturer	Sony
Device Category	Floppy Drive
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The OA-D3XV drives by Sony were the drives that used the disks would become the standard 3.5in Floppy Disk format. All of these drives use a physically incompatible interface to standard Shugart floppy disk controllers. This may have been intentional when they were released because they were all 600RPM and incompatible with existing 5.25in floppy controllers due to the higher data rate.

Drive Models

The OAD-3XV series changed rapidly as standards were being agreed on and adjustments were being made. Here are some of the significant differences between them. There are different PCB revisions between the drives, and I believe within each drive model, but I have not observed any functional differences between them.

Sony Series 30

The first machine to potentially use drives compatible with what would become the 3.5in standard would be the Sony Series 30 from 1980. However, the exact drives it used are unknown. There is an image in a document that appears to be a first hand account of developing the drive but the document has some provable factual errors and isn't very reliable. The photo it has is of a drive it claims is a "OA-D30V/OA-D31V" but it appears to be an earlier design with noticeable differences.

• Finger opening in front bezel for grabbing disk is much wider
• Top side head clamp appears to be cast metal
• Different bottom chassis metal casting tat may extend up the back

It is also highly probably that this was a prototype drive not meant to be shown in this context because in a May of 1981 of Popular Science you can see a drive that is much closer to the OA-D30V.

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  Unknown early Sony 3.5in floppy drive, possibly from Series 30.

OA-D30V

Likely first actual 3.5in compatible drive, these are the drives that needed the manual shutter disks, though some were sold with the auto shutter arm as well. They were designed and submitted to the Microfloppy Industry Committee (aka, Microfloppy Standards Committee) and quickly became the leading contender gaining large support. The first device to sell with one of these drives was most likely the Jonos Courier in June of 1982.

Some notable differences from the other drives:

• The auto-shutter arm is not present in early examples
• The drives are single sided
• The eject button must be held when inserting a disk, the drive is else wise always down in the loaded position with a door blocking the disk slot
• The head is only able to move to 70 tracks (thankfully the TPI and track 0 positions are the same and these disks are readable on later drives)

Found in:

• Jonos Escort
• Computer Devices Dot

Photos

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OA-D31V

This drive is mostly the same as the OA-D30V but has some changes suggested by the MIC. I have not seen one of these without the auto-shutter arm and were likely a redesign with that in mind. It is possible that the head could address 80 tracks, but I have not seen a system use that and cannot find a manual that states it can.

• All examples I have seen have shutter arm
• The disk lowering mechanism now locks in the upper position when no disk is installed and you do not have to hold eject to insert a disk
• Some of these drives may have "Auto Shutter" printed on the front bezel

Found in:

• Jonos Escort
• Computer Devices Dot

• HP-9121D 3.5" Double Density Single Sided Floppy Drive
• Sony SMC-70
• Sord M23P
• Apricot PC

OA-D32V and OA-D32W

These drives are most likely the final revision where they matched the accepted standard. The "W" variant of the drive is double sided for the first time. I do not have any examples of this drive.

• The magnetic coercivity of the disks is was changed, the earlier drives are not very compatible with media made for and after these drives
• The head can address 80 tracks