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View Full Version : Adding a 3.5" Drive to a 5150



tempest
May 20th, 2016, 09:17 AM
My IBM 5150 (with the 3rd BIOS revision) currently has two half height 5.25" drives and a full height hard drive in the other bay. While two 5.25" drives are nice, I'd much rather replace one of them with a 720K 3.5" drive. I have three questions about this:

1. Can I just stick any old 3.5" drive in the 5150 or does it need to be a specific kind of 3.5" drive?

2. Can I use the same floppy cable the 5.25" drive used? I think my cable has 3.5" connectors but I'm not sure.

3. Since 3.5" drives are smaller than a 5.25" drive, how do I fit it in? I've seen some pictures where the 3.5" drive has a nice plastic bezel around it, but I'm not sure how to find one of these or what they're even called (is it just a bezel or some kind of sled as well?).

glitch
May 20th, 2016, 09:26 AM
Any old 3.5" drive will work as 720K. There's an adapter you can get which is basically mounting rails and a plastic bezel. They're most commonly white or beige, and a cheap trick to make them black is to go get a can of vinyl dye spray and spray the faceplate. Unlike paint, vinyl dye soaks into the plastic and changes the color, so it won't chip off over time.

As long as your cable has the correct connector, you should be fine. There were adapters to go from the card edge connector to a dual-row pin connector.

You can also get floppy controllers that will allow the drive to function as a 1.44 MB drive -- they have their own controller and BIOS, and replace the default IBM controller.

vwestlife
May 20th, 2016, 09:27 AM
You need a mounting kit:

http://www.ebay.com/itm/182118392378

A kit like that includes everything you need (hardware-wise) to install a standard 3.5" floppy drive into an IBM 5150 PC, except for the brackets to mount two half-height drives into one of the full-height bays (but copious amounts of duct tape will also take care of that :) ). You can use it with any standard PC/XT floppy drive controller, and it will operate in 720K compatibility mode, so you can read and write 720K Double Density disks, but not 1.44 MB High Density disks.

If the rest of your drives are black and you want to match the color, you can also find the mounting frame (and of course the 3.5" floppy drive itself) with a black faceplate, however, in that case you'll probably need to buy the power and data cable adapters separately, as only the beige mounting kits seem to come bundled with them.

krebizfan
May 20th, 2016, 09:35 AM
Don't forget to remove/disable the termination on the 5.25" drive if you choose to make the 3.5" the A: drive.

pietja
May 21st, 2016, 04:12 PM
Black mounting frame http://www.ebay.nl/itm/181936485193

nc_mike
May 22nd, 2016, 01:04 PM
Don't forget to remove/disable the termination on the 5.25" drive if you choose to make the 3.5" the A: drive.

I've previously read other posts suggesting to remove/disable the termination on the 5.25" drive if you choose to make the 3.5" the A: drive

I have a 5160, with a high-density controller, and my 3.5" floppy is a 1.44MB A: drive and my 5.25" 1.2M floppy is my B: drive. They seem to operate OK except when I added a CF C: and D: drive via an XT-IDE adapter. When the 5.25" 1.2M B: drive is connected, the directories CF C: drive gets corrupted intermittently when written to. When I disconnect the 5.25" drive the CF C: drive doesn't get corrupted. The theory is that even though I think the BIOS of the FC isn't conflicting with the BIOS of the XT-IDE, we're not 100% certain, so I'm about to try a new XT-IDE that packs both the HD floppy BIOS into the same EPROM and the XT-IDE BIOS to eliminate that possibility (I'll do that anyway 'cause it will also allow be to lose the FDC, use a 16-bit multi-function adapter with non-BIOS FDC connector and thus free up a slot). I'm not sure if that will fix the CF C: drive from getting corrupted when the 5.25" 1.2M C: drive is connected - I've been wondering if maybe the corruption might have something to do with the termination you mention, but when I've looked at the rear of the 5.25" drive I have no idea how I'd disable the terminator. The drive is a Teac FD-55GFR, and it has jumpers listed here ( https://groups.google.com/forum/#!msg/comp.sys.ibm.pc.hardware.storage/U-2bPTdJZOc/ogjLfUcqYRAJ ) but I didn't see anything that referenced a terminator. What exactly happens if that isn't done? I've read that it is a good idea to remove a terminator on a floppy drive not at the end of a cable to 'not muffle the signal' - so I am really confused over what to look for re: floppy drive termination via jumper or chip.

Regards,
Mike

Chuck(G)
May 22nd, 2016, 01:29 PM
Don't sweat the terminator if it's not removeable (sometimes appears as a DIP or SIP in a socket).

Older 8" and 5.25' drives used a 150 ohm pullup, which was fine for long (>1m) cables, but completely overkill for the short distances used in the PC. The point was to reduce the possibility of line reflections by terminating both ends of a floppy cable. When two of the old drives with 150 ohm terminators were used, one had to be removed simply because driving a 75 ohm-to-Vcc load requires more power than the driver (7438) is rated for.

But later 3.5" and 5.25' drives simply use a large (>1Kohm) terminator and it doesn't matter if both drives have them connected or not.

nc_mike
May 22nd, 2016, 03:50 PM
Don't sweat the terminator if it's not removeable (sometimes appears as a DIP or SIP in a socket).

Older 8" and 5.25' drives used a 150 ohm pullup, which was fine for long (>1m) cables, but completely overkill for the short distances used in the PC. The point was to reduce the possibility of line reflections by terminating both ends of a floppy cable. When two of the old drives with 150 ohm terminators were used, one had to be removed simply because driving a 75 ohm-to-Vcc load requires more power than the driver (7438) is rated for.

But later 3.5" and 5.25' drives simply use a large (>1Kohm) terminator and it doesn't matter if both drives have them connected or not.

Thanks for clarifying that!

Mike

tempest
May 24th, 2016, 05:40 AM
I just looked, my cable only has 5.25" drive connectors on it (I think it's original). I'll have to find a cable with both on them, hopefully that won't be difficult.

Stone
May 24th, 2016, 06:45 AM
I've got some NOS universal dual floppy ribbon cables.

tempest
May 24th, 2016, 10:48 AM
Let me check, I may actually have one. If not, I'll take you up on that

Chuck(G)
May 24th, 2016, 11:27 AM
You can also crimp a 34-position female IDC connector onto the cable or get a 5.25" to 3.5" adapter (used to be very common; now quite rare).

tempest
May 25th, 2016, 05:32 PM
Found a spare cable. Now I just need a black 3.5" drive and a holder.

tempest
May 26th, 2016, 11:31 AM
Would this one work? http://www.ebay.com/itm/252143177435 or http://www.ebay.com/itm/222118349278

Stone
May 26th, 2016, 11:42 AM
The idiot selling the second one says it has a

'PATA/IDE/EIDE' interface. :-)

Chuck(G)
May 26th, 2016, 12:54 PM
So he can't count...

tempest
May 27th, 2016, 06:46 AM
So I assume that this (http://www.ebay.com/itm/252143177435) will fit in this (http://www.ebay.com/itm/181936485193) and together they'll fit in a half height slot?

jharre
May 27th, 2016, 07:31 AM
So I assume that this (http://www.ebay.com/itm/252143177435) will fit in this (http://www.ebay.com/itm/181936485193) and together they'll fit in a half height slot?

Yep, that looks like it should work.

Cimonvg
May 27th, 2016, 07:32 AM
hello
a bit related to the subject.. i like the idea of "clean" old floppy controler and a somewhat new 720kb read/write function.
But, when trying to read/write the 720kb , personally i have not made any connection to windows 7 usb flopyy to a 720kb disk. Perhaps i did buy a usb-floppy to cheap ??
Anyhow today , i tried this out and it works :)

Disassemble an old cdrom-writer usb drive. Mount a 120mb LS floppy drive (with IDE interface) instead of the cdrom-drive .


31379

i was able to read + write + (in CMD) format a:
...have not tried installing software that are copyprocted , perhaps it kind of not function ??

PS in windows 7 the drive appears as "matshita ls-120 ver5 00 usb Device"
/cimonvg

Chuck(G)
May 27th, 2016, 07:46 AM
The problem with USB and PATA floppy drives is that they're first cousins to SCSI floppies; that is, they're relative-sector addressed and assume a pre-selected layout. So, they'll do MFM 512x9x2x80, 512x18x2x80 formats--and in some cases, do 1024x8x2x80, but that's it--and it's "normal" sector headers. If you have an unusual ID address header, or a sector that's not 512 bytes, or more than 9 or 18 sectors, it won't understand.

AFAIK, it's been that way since the very first USB floppy drives.

Stone
May 27th, 2016, 08:41 AM
So I assume that this (http://www.ebay.com/itm/252143177435) will fit in this (http://www.ebay.com/itm/181936485193) and together they'll fit in a half height slot?Even the other floppy would work.

The fact that the idiot can't count in no way affects the drive's performance. :-)

Cimonvg
May 27th, 2016, 09:08 AM
Hhello again - just to emphasise , read/write and format 720kB floppy ;)
..just do not format in windows explorer - it says "wrong format", format of an usb-720kb disk is done in CMD c:\format a:/F:720
/cimonvg


hello
....
Anyhow today , i tried this out and it works :)
...
i was able to read + write + (in CMD) format a:
....
/cimonvg

gertk
May 27th, 2016, 09:16 AM
Sometimes you can find one of these:

http://www.ebay.com/itm/EPSON-SD-700-SD-800-Combo-5-25-3-5-Floppy-Drive-/291773421693?hash=item43ef0d187d:g:vDEAAOSwagdXRf0 3

Takes even less space..

Chuck(G)
May 27th, 2016, 09:41 AM
Are those rare? I've still got a carton of NOS Teac FD-505s. Maybe I should consider selling them...

glitch
May 27th, 2016, 09:52 AM
I've had a few of them, I generally found them to be less reliable than standard separate drives. Anyone else share that experience?

tempest
May 27th, 2016, 10:06 AM
Are those rare? I've still got a carton of NOS Teac FD-505s. Maybe I should consider selling them...

Well they're not common and they're obviously desirable from a space perspective. I've always avoided them because they were A. Expensive, and B. As Glitch pointed out, usually less reliable.

Also is that a 360K 5.25" or a 1.2MB 5.25"?

krebizfan
May 27th, 2016, 10:14 AM
I thought they were as reliable as other thin drives - considerably reduced compared to standard drives. The paired thin drives are also a pain to clean.

Combo drives only accounted for about 1% of production so rare compared to standard 3.5" drives but much more numerous than 8" drives.

Chuck(G)
May 27th, 2016, 10:50 AM
Also is that a 360K 5.25" or a 1.2MB 5.25"?

1.2MB. The 3.5" part isn't too bad, the 5.25" is a bit less reliable that the single-unit ones; uses leadscrew type positioner, rather than taut-band, probably because of space constraints. Still, for casual floppy use, they'll turn in a lot of mileage.

tempest
May 27th, 2016, 03:22 PM
Bah, 1.2MB 5.25"'s I don't need. 360K or bust!

tempest
June 11th, 2016, 10:13 AM
I got around to trying this today and discovered that my cable won't work because it needs that 5.25" 'edge connector' type connector on both ends as the card itself has the same connector as the 5.25" drive. My cable has the standard 3.5" connector on the end of it.

What kind of cable do I specifically need to do this?

Chuck(G)
June 11th, 2016, 10:31 AM
Again, the simplest thing to do is to crimp a 34-pin IDC connector onto the cable next to the standard Berg connector.

Like this (http://www.ebay.com/itm/2-Pack-34-Pin-Card-Edge-Female-IDC-Connector-for-Flat-Ribbon-Cable-FC-034C-/270850810044?hash=item3f0ff760bc:g:j9gAAOSwFNZWznQ F)

You can do the crimping carefully with a small machinist's vise, a bench vise, a pair of Channelocks, a Vise-Grip tool--or preferably, with a tool made for the purpose. Use a piece of wood to protect the contact edge; make sure that the cable is straight and that pin 1 (striped) on the cable matches the little triangle on the connector. You'll be fine.

krebizfan
June 11th, 2016, 10:42 AM
I got around to trying this today and discovered that my cable won't work because it needs that 5.25" 'edge connector' type connector on both ends as the card itself has the same connector as the 5.25" drive. My cable has the standard 3.5" connector on the end of it.

What kind of cable do I specifically need to do this?

I am not sure if any floppy cable had edge connectors at both ends and a pin connector for a 3.5" floppy. Early floppy cables for IBM PCs had all edge connectors and later cables that had both pins and edge connectors typically had a pin connector for the controller side. If you have a spare floppy cable, you could replace connectors to match your needs.

There used to be a whole array of adapters to switch edge connectors to pin connectors. If you can find appropriate versions of that, your existing cables and drives could be made to work. I didn't find any in a quick web search. What is likely to be faster than trying to find scarce adapters from 30 years ago is to get a replacement floppy card with a pin connector.

Chuck(G)
June 11th, 2016, 10:52 AM
I've got a few of the adapters, but they're pretty thin on the ground. They used to be packaged with the 3.5"-to-5.25" floppy adapter kits, along with a power cable adapter--but all that seems to be ancient history.

All "combo" floppy cables I've ever seen have 5 connectors--two card-edge, next to two pin connectors and a pin connector at the controller end. The card-edge FDCs lasted but a short time.

DDS
June 11th, 2016, 11:16 AM
I've seen 5.25" to 3.5" bay adapters on auction within the last couple of weeks with the pin to card edge adapter included. I also saw an auction recently where they were selling the adapters by themselves. Just keep your eyes open because they do come up from time to time. There are also auctions for vintage floppy cables like this one:

http://www.ebay.com/itm/Vintage-PATA-IDE-SERIAL-RIBBON-Cables-for-OLD-HDD-5-25-Old-Floppies-and-More-/181631978790?hash=item2a4a1c0d26:g:rTQAAOxySoJTRxc V

Take a look at this one:

http://www.ebay.com/itm/Teac-CS-235R-CS235R-5-25-Adaptor-Kit-For-3-5-Micro-FDD/370570148894?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D36862%26meid%3De0f58a1f527f4e8ca8d5b6469a93 3e2a%26pid%3D100011%26rk%3D4%26rkt%3D10%26sd%3D222 111418023

The adapter you're looking for is in the middle of the picture.

Old cables can be canibalized for parts. Once you have some cable and some connectors it's easy enough to build what you need. One of the frequently used tools in my bag of tricks is a rather long 34 conductor cable with one of each type of connector at each position. That produces an almost universal floppy cable that you can use to get things rigged together for testing purposes. Then you can build a "custom" cable for your particular configuration when you're sure what is going to go where.

Stone
June 11th, 2016, 11:33 AM
The adapter you're looking for is in the middle of the picture.No, that isn't what he is looking for.

That one has a female IDC connector AND a male card edge connector while the one he wants is the complete opposite, i.e., a male IDC with 34 pins and a female card edge connector.

FWIW, I have a ~ 15", 34 conductor ribbon cable with a 34 pin male IDC connector at one end and a female card edge connector at the other. Now, that would work to connect the standard controller end connector of the floppy ribbon cable to one that would connect to the 5150's floppy controller.

tempest
June 11th, 2016, 12:49 PM
Again, the simplest thing to do is to crimp a 34-pin IDC connector onto the cable next to the standard Berg connector.

While probably true, I honestly don't have any means of doing that. Does anyone sell one of these pre-crimped?



FWIW, I have a ~ 15", 34 conductor ribbon cable with a 34 pin male IDC connector at one end and a female card edge connector at the other. Now, that would work to connect the standard controller end connector of the floppy ribbon cable to one that would connect to the 5150's floppy controller.
Not sure I follow what you're saying. It sounds like I need a cable like this:

Female Card Edge > Female IDC > [Wire Twist] > Female Card Edge

Does that sound right?

krebizfan
June 11th, 2016, 01:01 PM
While probably true, I honestly don't have any means of doing that. Does anyone sell one of these pre-crimped?


Not sure I follow what you're saying. It sounds like I need a cable like this:

Female Card Edge > Female IDC > [Wire Twist] > Female Card Edge

Does that sound right?

Sounds right. Unfortunately, I don't know of anyone who sells one like that premade. I suggest picking up an extra floppy cable. Cheap and the modification needed is relatively easy.

Chuck(G)
June 11th, 2016, 01:17 PM
Send me a cable and a connector and I'll crimp it on for you. I usually make my own floppy cables anyway.

tempest
June 11th, 2016, 01:24 PM
Send me a cable and a connector and I'll crimp it on for you. I usually make my own floppy cables anyway.

I already have a cable that goes Female IDC > Female IDC > Female IDC > Female Edge Connector > [Twist] > Female IDC > Female Edge Connector. If I'm right all that needs to be changed is to put a female edge connector at the beginning of the chain. If I send it to you, could the extra female edge connector be taken off and put on the end? That would save some time and money.

DDS
June 11th, 2016, 01:37 PM
"That one has a female IDC connector AND a male card edge connector while the one he wants is the complete opposite, i.e., a male IDC with 34 pins and a female card edge connector"

Yep... I see what you mean.

"Female Card Edge > Female IDC > [Wire Twist] > Female Card Edge"

That would be the correct setup if you want the 3.5" drive to be B:. If you want it to be A: it needs to be on the end of the cable after the twist.

Another point to quibble over but it might mess up any searches you do is that technically both of those connector types are IDC or "Insulation Displacement Connector". This refers to the way the connector connects to the ribbon cable, not the way it connects to the floppy drive. The older type is a card edge or keyed card edge connector. The newer type seems to go by various names like pin header connector, header type connector or Berg connector after one of the companies that make them.

tempest
June 11th, 2016, 01:41 PM
That would be the correct setup if you want the 3.5" drive to be B:. If you want it to be A: it needs to be on the end of the cable after the twist.

That actually is what I want since I still want the ability to play 5.25" booters. The 3.5" drive is only for transferring files.

Chuck(G)
June 11th, 2016, 02:14 PM
PM me with your druthers. It wouldn't be impossible that I already have the parts kicking around.

Stone
June 11th, 2016, 02:15 PM
That actually is what I want since I still want the ability to play 5.25" booters. The 3.5" drive is only for transferring files.Either drive can play booters.

Either drive can boot a DOS floppy.

I use a disk with this on it:

'Boot-B:' which is a program that creates a new boot sector for a disk in drive A: which when booted will pass the boot process over to the B: drive.

I've been using this for years to simplify many floppy issues.

With this utility you can boot from A: or B: at will regardless of their size/format.

Stone
June 11th, 2016, 03:20 PM
Not sure I follow what you're saying. It sounds like I need a cable like this:I think you missed the point. The cable I described will plug in to the cable you already have and make it compatible with the card edge connector on your floppy controller.

tempest
June 18th, 2016, 04:38 PM
Ok I got my cable and I'm still having trouble. I use my DOS 5 boot disk to get to a DOS prompt, but when I tried to access the 3.5" drive (I have it as the B drive) both disk drive lights went on. I attempted to format the 3.5" and it seemed to think it was a 360K disk then said it couldn't read the boot sector. Do I have to configure something for the system to recognize the 3.5" drive as 720K? The motherboard is already set to two drives so that's no it.

krebizfan
June 18th, 2016, 04:47 PM
This might help: http://minuszerodegrees.net/5150_5160/720k/5150_5160_720k_driversys.htm

DRIVER.SYS should permit formatting.

tempest
June 18th, 2016, 04:56 PM
Yeah I just read that. I had two problems:

1. I was using a 1.44MB disk (don't know how that snuck in my 720K pile)
2. I didn't have that drive enabled

I don't have a hard drive up and running at the moment, so my testing will have to wait until next week. I tried formatting a 720K disk on my DOS 6.22 box but I can't read it using DOS 5 (it says Sector Not Found). I assume this is because I formatted it in DOS 6 and not because the drive is bad. Interestingly when I tried format again (without the driver) it tried formatting it as a 360K disk but said Invalid Media Track 0 is Bad. I'm worried that my 3.5" drive may not be working, but I can't test that until I get my hard drive running.

krebizfan
June 18th, 2016, 05:00 PM
DOS 6.22 should produce a disk that DOS 5 can read. FAT-16 stayed the same. So either one drive is out of alignment or dirty or something screwy is going on.

tempest
June 18th, 2016, 05:06 PM
DOS 6.22 should produce a disk that DOS 5 can read. FAT-16 stayed the same. So either one drive is out of alignment or dirty or something screwy is going on.

I was afraid of that. How do I diagnose this?

krebizfan
June 18th, 2016, 05:24 PM
I was afraid of that. How do I diagnose this?

I would try cleaning both drives first. Opening up and making sure the heads are still attached could save a lot of fruitless debugging. Checking for alignment is hard and the proper tools are long gone. I would try an expendable install diskette in 720kB format. Publishers likely will have close to perfect alignment so if a drive fails to read the install disk, that drive probably has major problems.

If not that, the issue is really complex and expect to be offered many incorrect solutions before anyone figures out what is wrong.

Chuck(G)
June 18th, 2016, 06:27 PM
You want a drive (5.25") on the far end (A:) and only a 3.5" drive on the middle (B:). Only one drive light should be lit at any one time. You can use a 1.44M drive if you have to. To get an easy 720K from a pile of 1.44M disks, cover over (with opaque tape or label, the density indicator hole.

Both drives should be set to the second drive select. (sometimes DS1; sometimes DS2, depending on how the manufacturer counts).

If both drive lights come on immediately on power-up, you've got one connector of the cable turned upside-down somewhere. (note the the "twist" is closest to the pin 1/2 edge.)

tempest
June 18th, 2016, 07:08 PM
That's how I have the cable connected. The drive light issue only happened once, no idea why but it seems to have gone away.

How do you set the drive select? Jumpers? Maybe that's the problem?

tempest
June 19th, 2016, 01:32 PM
It's the darn floppy drive. Plugged another one in and it works like a charm.

Chuck(G)
June 19th, 2016, 01:34 PM
Floppy drive faceplates vary from manufacturer to manufacturer. They're not interchangeable. Some use a couple of screws, other have tabs molded into the faceplate that snap into slots in the drive body.

tempest
June 19th, 2016, 02:59 PM
Yeah I just noticed that the one on my black drive has side snaps where the one on the beige drive has top and bottom snaps. Looks like I'll just have to snag a new black one off ebay or deal with the horrors of a beige drive in a black case (nooooooo!).

Chuck(G)
June 19th, 2016, 04:09 PM
You can also get a rattle-can of safe-for-plastic black paint. Who's gonna know? :)