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First post, by Lennart

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I recently acquired an external Iomega Floptical drive with SCSI interface. I'd like to use this instead of a regular 3.5" floppy drive, so it has to be bootable and it should be assigned to drive letter A. Therefore I need a SCSI controller with a BIOS that supports Floptical drives. I have an Adaptec AHA-1542CF ISA SCSI controller, which supposedly should have BIOS support for Floptical drives according to the installation guide (http://download.adaptec.com/pdfs/installation … ha1540cf_ig.pdf). It says:

SCSI Device Configuration and Advanced Configuration Options: These screens are accessed from the Configuration screen described above. The AHA-1540CF/1542CF offers a number of options for advanced applications. Fast SCSI, Floptical support, and an alternate floppy controller address are enabled here.

However, that section within its BIOS configuration utility doesn't contain any option for enabling Floptical support. I do have an option for bootable CD-ROM support, which isn't mentioned in the installation guide. That got me thinking, could it be that they axed bootable Floptical support in favor of CD-ROM in later revisions of the BIOS?

I found this post mentioning that there were 3 different BIOS revisions for the AHA-1542CF: v2.01 (1993), v2.10 (1994) and v2.11 (1995). My card has v2.10. Perhaps v2.01 does have Floptical support?

Is there anyone with an AHA-1540CF or AHA-1542CF who has an other BIOS revision and would be willing to check the BIOS configuration utility for Floptical support? I'd also like to hear from people who have an AHA-1540C or AHA-1542C (so no Fast SCSI support) or the AHA-1542CP (which should be PnP). I suspect that the 1542CP won't have support, because it's newer, but the AHA-154xC will probably have it.

Thanks in advance!

Reply 2 of 16, by Cyrix200+

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I have this AHA-1540/42CP that has BIOS version 1.03 according to the sticker. I don't know what the difference is between the various 154x cards, but if you think it might help I'm willing to check it out.

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Reply 3 of 16, by Lennart

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yawetaG wrote:

SCSI superfloppies are treated as removable SCSI hard disks, not regular floppy drives.

Yes and no. They are recognized as removable SCSI hard disks if you don't have any special BIOS support for them. But they can be recognized as a regular floppy drive if your SCSI controller has specific BIOS support for Floptical drives. The user guide for the AHA-1520A for instance mentions:

Drives A and B are reserved for floppy drives in the DOS environment and may be assigned to either standard diskette drives or Floptical drives.

AFAIK that wouldn't be possible with a removable SCSI hard disk. The AHA-1520A has a jumper to enable or disable Floptical support in the BIOS, so it seems that it does something special. There even appears to be a version of an Adaptec card specifically targeted at Floptical drives, the AHA-1520FS or AHA-1522FS: https://storage.microsemi.com/en-us/support/_ … isa/aha-1522fs/

Cyrix200+ wrote:

I have this AHA-1540/42CP that has BIOS version 1.03 according to the sticker. I don't know what the difference is between the various 154x cards, but if you think it might help I'm willing to check it out.

Thanks, that might help! 😀 I suspect it won't have support for Floptical though, as it's a later model than the AHA-1542CF. For as far as I've been able to find out, the first letter stands for the hardware revision. So either A, B or C. The C models have fewer switches or jumpers, because most of its settings can be set in the BIOS configuration utility. The F of my CF stands for Fast SCSI support (10MB/s instead of 5MB/s). The P of your CP should stand for Plug 'n Play, as you can assign IRQ and I/O addresses via PnP with that card. If it's a 1540, it won't have a separate controller and connector for regular floppy drives. If it's a 1542, it does have a regular floppy controller besides the SCSI controller.

Reply 6 of 16, by Lennart

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@Cyrix200+ many thanks for checking and making those photos! 😀 It confirms what I thought, it doesn't have any specific options for Floptical drives. My AHA-1452CF has the same menu options as yours.

Warlord wrote:

what iomega drive do you have, Zip drives are not floppy drives, they are removable disks. Think like USB drive but a floppy.

It's the Iomega Io20s inside an Iomega F20X external case. So it's definitely a Floptical drive rather than a Zip drive. Unfortunately I don't have any 21MB Floptical disks yet, but the drive also reads regular 720KB and 1.44MB floppies.

The Wikipedia article on Floptical specifically mentions that "to allow for a high degree of compatibility with existing SCSI host adapters, Floptical drives were designed to work as a standard floppy disk drive, and not as a removable hard disk." So now I just need to know which SCSI host adapters support it. 🤣

Reply 8 of 16, by CwF

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I no longer have a 1542 but did and it could format the 21MB floptical, maybe that's what's special. It shoed as C as I remember. I believe a 2940 could use it but not format. Buslogic controllers could have the floptical option in non raid 1.41 bios's for the flashpoints. I think I still have the controller that boots as A drive.

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Reply 9 of 16, by Lennart

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It took a while, but I'm finally able to answer my original question 😀

I recently purchased an Adaptec AHA-1540CF with v2.01 firmware. This time it doesn't have an option to boot from CD-ROM, but it does have the option to enable Floptical BIOS support!

After enabling the option, the Floptical drive was recognized by the BIOS and got assigned as drive A. I could use it as a regular floppy drive just fine.

As there doesn't seem to be much information around on the internet about the Iomega Io20s drive and the Iomega F20X case, I figured I should make some photos.

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Reply 10 of 16, by weedeewee

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any chance of getting an image of the bios ?

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Reply 11 of 16, by Tetrium

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Lennart wrote on 2022-03-26, 15:02:
It took a while, but I'm finally able to answer my original question :) […]
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It took a while, but I'm finally able to answer my original question 😀

I recently purchased an Adaptec AHA-1540CF with v2.01 firmware. This time it doesn't have an option to boot from CD-ROM, but it does have the option to enable Floptical BIOS support!

After enabling the option, the Floptical drive was recognized by the BIOS and got assigned as drive A. I could use it as a regular floppy drive just fine.

As there doesn't seem to be much information around on the internet about the Iomega Io20s drive and the Iomega F20X case, I figured I should make some photos.
P_20220326_154101.jpg
P_20220326_154139.jpg

Awesome! There's indeed relatively little info about this floptical drive. It's a shame you don't have any of its disks as neither do I. I got one single internal floptical drive (iirc it has a SCSi connector and not the typical 34p floppy connector) but I put it away since I didn't have any of its disks anyway.

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Reply 12 of 16, by Lennart

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weedeewee wrote on 2022-03-26, 15:35:

any chance of getting an image of the bios ?

I don't have any hardware to create an image of the BIOS I'm afraid.

Tetrium wrote on 2022-03-26, 19:06:

Awesome! There's indeed relatively little info about this floptical drive. It's a shame you don't have any of its disks as neither do I. I got one single internal floptical drive (iirc it has a SCSi connector and not the typical 34p floppy connector) but I put it away since I didn't have any of its disks anyway.

You're probably right, I think all Floptical drives have a SCSI connector. As a matter of fact I did manage to find 5 NOS Floptical disks some time ago. Sadly the drive is a bit flaky with these disks. Might be the drive or the disks, I don't know. Usually the drive won't be able to read the disks, but sometimes it does work and I can format the disks and copy files over to them. Regular floppy disks always seem to work fine though.

Reply 13 of 16, by weedeewee

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Lennart wrote on 2022-03-27, 17:13:
weedeewee wrote on 2022-03-26, 15:35:

any chance of getting an image of the bios ?

I don't have any hardware to create an image of the BIOS I'm afraid.

I understand, just having it in the computer is not enough... oh wait it sometimes is.
There's a way to do it with dos debug though we'll have to google for it.

http://mess.redump.net/dumping/dump_bios_using_debug

make sure the scsi bios isn't being shadowed for this procedure
find out which memory address it is located at and use the instructions wisely.
The instructions will have you creating two files of 32k each, and you'll need to use the memory address that your scsi rom is located at, not the address that is currently in the instructions,
but dependent on the actual size of the scsi bios, only one might be enough.

good luck.

edit: dang there was something else I wanted to mention but I lost it.

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Reply 14 of 16, by Lennart

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weedeewee wrote on 2022-03-27, 17:26:

I understand, just having it in the computer is not enough... oh wait it sometimes is.
There's a way to do it with dos debug though we'll have to google for it.

Actually, in this case I don't think it is enough to have the AHA-1542CF installed in your PC in order to dump the ROMs. There are two of them: one contains the configuration program and the PC BIOS expansion ROM, and the other one contains microcode for the on-board Zilog Z80 microcontroller. That second ROM is not exposed on the ISA bus, thus you can't use debug to dump it.

Anyway, I did a quick search and it turns out that someone has already dumped them: http://minuszerodegrees.net/rom/rom.htm

The post I found earlier on VOGONS does seem to suggest that the ROM versions are tied to particular hardware revisions, so it might not work if you downgrade or upgrade the ROMs of your card.

Reply 15 of 16, by weedeewee

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Lennart wrote on 2022-03-27, 20:51:

Actually, in this case I don't think it is enough to have the AHA-1542CF installed in your PC in order to dump the ROMs. There are two of them: one contains the configuration program and the PC BIOS expansion ROM, and the other one contains microcode for the on-board Zilog Z80 microcontroller. That second ROM is not exposed on the ISA bus, thus you can't use debug to dump it.

Anyway, I did a quick search and it turns out that someone has already dumped them: http://minuszerodegrees.net/rom/rom.htm

The post I found earlier on VOGONS does seem to suggest that the ROM versions are tied to particular hardware revisions, so it might not work if you downgrade or upgrade the ROMs of your card.

Most of the time the microcode is for the actual scsi controller, the scsi bios on the other hand is all code that runs on the computer and might in some circumstances have some patches for microcode fixes, though that is not a general rule.

Also, I looked at the -0° site and they sadly do not list which version the roms are, so that means downloading them all and looking with a hex editor.
ok, it's the "553601-00 C BIOS C38D" file that has the floptical & v2.01 mentioned in it .

a bit dissapointed that both cdrom & floptical isn't an option. oh well.

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Reply 16 of 16, by evanevery

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Hey guys, lots of good info here! Unfortunately, none of this helped me... 🙁

I'm trying to start a more generalized "Floptical" thread for any/all things FLOPTICAL related (not just the 1542CF, but also other controllers, software, and firmware). Your expertise is greatly appreciated!

The Great Floptical Debacle...