VOGONS

Search

Common searches

XT-FDC - Four Drive Floppy Controller - An Honest Review

Topic actions

First post, by mockingbird

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie

The XT-FDC is a worthless piece of garbage.

Here are a couple of links that describe the project in-depth:

https://www.vcfed.org/forum/forum/vcwiki/vcwi … 081-xt-fdc-rev1
https://www.retrobrewcomputers.org/doku.php?i … sa:xt-fdc:start

Here are the two boards I built:

IMG_1667.JPG
Filename
IMG_1667.JPG
File size
584.42 KiB
Views
974 views
File license
Public domain

One board has used parts in it, and the second board was built from parts ordered exclusively from an authorized distributor (Newark), as all the parts, except for the PC8477B are still being produced and can be obtained. The EEPROM was programmed with the 2.2 BIOS latest and verified with a TL866 vartiant.

The inspiration to build this project came from Tech Tangent's Youtube video titled More than two floppy drives?. In his video, he laments at the end how he didn't use the XT-FDC instead of paying a lot for his current floppy controller.

The truth of the matter is that he is way better off with his current card. The XT-FDC BIOS simply does not work properly, at least not on 486-class PCs. I tested this on both the ECS UM4980 and the Asus VL/I-486SV2GX4. If the card is used as a "dumb" controller (If JP1 is open which disables the boot ROM), it works properly. If JP14 is open, the card won't work with the ROM enabled. When the card does work with the ROM configured, floppy access is very, very slow (maybe this was only tested on an XT).

Even with the card working with the ROM enabled, I could not get the second port to work properly. With a 360K (verified working) drive attached, when accessed as drive B:, the LED comes on but the drive won't spin.

So just a warning for anyone needing a controller for more than two floppies (if your BIOS doesn't support it natively). This is not a good solution. The project seems to have been abandoned, and I haven't seen any new BIOS updates.

What I probably will end up doing is just using these as dumb controllers on two seperate computers and just having only two floppies per computer.

mslrlv.png
(Decommissioned:)
7ivtic.png

Reply 1 of 6, by Horun

Posted on 
User metadata
Rank l33t++
Rank
l33t++

Thanks ! Can you go thru the different ways you tried it on the 486 board ?

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 6, by mockingbird

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie
Horun wrote on 2021-07-12, 00:04:

Thanks ! Can you go thru the different ways you tried it on the 486 board ?

Certainly:

1) With JP1 shorted and open (Boot from on-board ROM or boot using motherboard floppy setting)
2) With JP14 shorted and open (secondary or primary FDD... As secondary FDD, I could not get it to work at all)

That's pretty much it... It's not that complicated. The on-board option ROM setup is pretty basic. It gives you a choice of 0-3 (Primary 1 and 2 and secondary 1 and 2) and then asks you to choose 0 or 1 (drive 1 on the cable or drive two on the cable - after or before the twist).

I also tried using both cards at the same time to see if I could just use the first port of two different cards, but I could not get that to work either...

Even when it does work, for some reason the floppy access is too slow to use realistically... I saw this mentioned in the Vogons Wiki for a 4 port ACC Microelectronics card as well from the 80s (which I also possess, incidentally)... I may try to obtain the 1.0c BIOS for the ACC card because I have not been avle to get it to work at all with the 1.0a bios. But it's not critical for me because I just decided to ultimately use two seperate computers. One computer will have a 360K and 1.44MB drive and the other a 1.2MB and 1.44MB drive. Maybe I can even get LS120 support on the Asus board seeing as how it has an Award 4.51 BIOS.

mslrlv.png
(Decommissioned:)
7ivtic.png

Reply 3 of 6, by Caluser2000

Posted on 
User metadata
Rank l33t
Rank
l33t

Who manufactured those particular fdd boards?

Folk from around the planet are producing those.

I was luckt enough to score a couple old used late '80s early '90s HD/DD 8-bit fdd controller cards that still work perfectly.

Any fdd controller on 16-bit ISA cards should work fine and dandy on 8-bit (with a small tsr loaded when needed for HD fdd access) or 16-bit ISA cards natively.

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 4 of 6, by mockingbird

Posted on 
User metadata
Rank Oldbie
Rank
Oldbie
Caluser2000 wrote on 2021-07-12, 01:15:

Who manufactured those particular fdd boards?

This is a custom-produced FDD board by some folks at the Vintage Computers forum. You take the design files and then order the boards yourself and then populate with the specified components.

mslrlv.png
(Decommissioned:)
7ivtic.png

Reply 5 of 6, by Horun

Posted on 
User metadata
Rank l33t++
Rank
l33t++

Thanks for the info ! I have a DTK PII-151 8bit isa from about 1987 with ROM for XT and original AT's to allow HD 1.2MB and 1.44MB drives (as well as standard 360k & 720k) to work on old boards with no HD capability.
Have it currently in a Portable XT and it is a bit slower for drive access than a standard XT floppy card using the Mobo bios but not so much on an old XT computer to notice.
I just wondered if this new card worked as easy (the DTK works great on any XT/AT so far) but sounds like it may have some issues...
Thanks again ! and here is a picture of the old card...

Attachments

  • floppy card.jpg
    Filename
    floppy card.jpg
    File size
    337.52 KiB
    Views
    917 views
    File license
    Public domain
  • portable.jpg
    Filename
    portable.jpg
    File size
    373.82 KiB
    Views
    917 views
    File license
    Public domain

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 6 of 6, by maxtherabbit

Posted on 
User metadata
Rank l33t
Rank
l33t

So really your complaint is with the option ROM and not the hardware at all 🤣

Sounds like the card is a perfectly capable FDC if you have software support sorted

Go to top of page Go to top of page
Back to General Old Hardware
Close window
Close window