• Please review our updated Terms and Rules here
  • Exhibitor application for VCF West 2022 is now open! If you are interested in exhibiting, please fill out the form here.
  • Here are the results of the VCF East 2022 Post Event Survey: Survey Results

Ibm 5150 + 3 drives + 1 hd

gerrydoire

Veteran Member
Joined
Aug 25, 2008
Messages
1,145
Incase this is not possible, I figured I'd ask.

I have an IBM 5150, I put in 3 drives, with a card that can handle 4.

All 3 work, 2 360's, 1 1.44meg.

When I throw in a 20 meg seagate and MFM card, this device defaults
to Drive C and, my floppies do not work past the A: drive, is it possible
to have this C Drive boot to another letter, or not possible?

(I did have it working with 2 floppies drives + HD which was a simple layout)

:confused:
 

paul

Veteran Member
Joined
Mar 18, 2004
Messages
808
Location
New Zealand
Does the MFM card have a floppy controller on board? If so and not disabled, it would be in conflict with the dedicated floppy controller
 

gerrydoire

Veteran Member
Joined
Aug 25, 2008
Messages
1,145
Does the MFM card have a floppy controller on board? If so and not disabled, it would be in conflict with the dedicated floppy controller

The MFM controller has no on board floppy abilities.
 

fs5500

Experienced Member
Joined
Nov 5, 2008
Messages
438
As you know, IBM PC 5150/5160 supports 4 FDDs.

If you're willing to add 3EA of Floppy and 1 or 2EA of HDD, Default HDD Drive must be D: (Not C: as common PC)

--> A: B: C: <-- Floppy / D: <-- HDD

But 4EA of Floppy, A: B: C: D: <-- Floppy / E: <-- HDD

To set default HDD Drive C:, you must install 1 or 2 floppy only.

This enable from DOS 1.x to 4.x.

If your DOS version is upper 5.0 or higher, you can use only 2EA of Floppy Drive. (Default HDD is C:)
(In this case, 1EA of FDD can't be recognized correctly on DOS 5.0 or higher.)
 
Last edited:

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
DOS controls the assignment of drive letters.
With three floppy drives, and a hard drive with one partition, then to be expected is:

Boot from DOS 4 or earlier: Floppy drives are assigned A:/B:/C: with hard drive becoming D:
Boot from DOS 5 or later: Floppy drives are assigned A:/B:/D: with hard drive becoming C:
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
(I did have it working with 2 floppies drives + HD which was a simple layout)
Was that using the standard IBM floppy controller, or using the 4-drive floppy controller?

I have an IBM 5150, I put in 3 drives, with a card that can handle 4.
All 3 work, 2 360's, 1 1.44meg.
By "all 3 work", which of the following do you mean:
* All three drives are known to work.
* When connected to the 4-drive floppy controller, they were appearing as A:, B: and C:

I put in 3 drives, with a card that can handle 4.
Does that 4-drive floppy controller have a BIOS expansion ROM. If yours does, what ROM address is that card configured for?
 

gerrydoire

Veteran Member
Joined
Aug 25, 2008
Messages
1,145
I have a card that supports 4 floppy drives, when 3 are connected to it, with no HD, all 3 work as they should.

When I add a MFM Hard drive to the mix, the first floppy works, the next two do not and the HD comes up as C:\:

At boot up time before the MFM Hard Drive kicks in, the floppy controller assigns the floppy drives as A: B: C:,
when the MFM Card boots in, the MFM also assigns the HD as C: leaving two floppies unaccessible.

Ideas?

:)
 

krebizfan

Veteran Member
Joined
May 23, 2009
Messages
5,334
Location
Connecticut
Which cards are being used? It may be possible to floppy controller to place drives as A:, B:, and then put the remaining floppy drives after any hard drives. I know some cards capable of handling 4 internal floppy drives had jumpers to permit this. Without setting jumpers and appropriate drivers, you will be stuck with only 2 floppy drives together with a hard disk.
 

JohnElliott

Veteran Member
Joined
Sep 1, 2006
Messages
578
Location
Sussex, UK
At boot up time before the MFM Hard Drive kicks in, the floppy controller assigns the floppy drives as A: B: C:,
when the MFM Card boots in, the MFM also assigns the HD as C: leaving two floppies unaccessible.

That isn't how it works. Drive letters are assigned by DOS, not card ROMs; at BIOS level, floppy drives are numbered 0, 1, 2, 3 and hard drives 128, 129 etc.

If you use DEBUG to call INT 11h, what are bits 6 and 7 of the value returned?

Code:
debug
-a100
0C72:0100 int 11
0C72:0102 int 3
0C72:0103
-g=100

AX=C823  BX=0000  CX=0000  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=0C72  ES=0C72  SS=0C72  CS=0C72  IP=0102   NV UP EI PL NZ NA PO NC
0C72:0102 CC            INT     3
-

(In this example, run on a single-floppy PC, the value returned in AX was C823 -- ie, bits 6 and 7 were 0. Which you'd expect on a single-floppy PC like the one I was testing on).
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
I have the same 4-drive floppy controller.
I also have an IBM 5150, ST-10 card, and ST-225 drive.

Give me some time and I'll see how my setup behaves.
 

fs5500

Experienced Member
Joined
Nov 5, 2008
Messages
438
You had better test it from DOS 1.x, 2.x, 3.x, 4.x, 5.x, 6.x

I think the result must be nearly same from DOS 2.x to 4.x.
I also tested PCE IBM 5150 emulator with original 5150 and 5160 config
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
I have just tried my setup of the hardware. All worked as expected.

Scenario 1 - No Hard Drive Controller

First, I fitted my 5150 with the FDC-344 floppy controller (UNIQUE) and three floppy drives:
On first connector: 360K + 1.2M
On second connector: 1.44M

Put a DOS 6.22 boot disk into the 360K drive, and then booted.
Appeared was:

fdc_344_1.jpg


Above, even though it is DOS that assigns drive letters, the FDC-344 BIOS displayed what I guess was its predictions about the future drive assignments.
All three floppy drives worked (as A: / B: / C: ).

Ran DEBUG and determined that the FDC-344 controller BIOS sits at CA000. No jumpers to change that. So, no possible BIOS ROM address conflict with the IBM/Xebec hard drive controller that I was about to insert (it sits at C8000).

Scenario 2 - Added Hard Drive Controller, With IBM DOS 3.3 on Hard Drive

Removed boot floppy.
Fitted 200W clone power supply into 5150 (to cater for hard drive power consumption).

Added an IBM/Xebec hard drive controller (Variation #2 shown [here]).
Added a Seagate ST-412 preloaded with IBM DOS 3.3

Booted.

The FDC-344 controller displayed exactly the same text as it did before on the previous boot, and during that time I saw all three floppy drives being searched.
The 5150 booted from the hard drive.
DOS assigned drive letters as follows: A=360K, B=1.2M, C=1.44M, D=hard_drive
That was as expected (pre DOS 5).

At the D:> prompt (hard drive), trying to run programs resulted in the 1.44M drive being searched. That turned out to be because the hard drive's AUTOEXEC.BAT contained PATH=C:\DOS

All floppy drives behaved as expected. I could read data on all of them.

Scenario 3 - MS-DOS 6.22 on Hard Drive

Reformatted the hard drive with MS-DOS 6.22
Booted.

The FDC-344 controller displayed exactly the same text as it did before on the previous boot, and during that time I saw all three floppy drives being searched.
The 5150 booted from the hard drive.
DOS assigned drive letters as follows: A=360K, B=1.2M, D=1.44M, C=hard_drive

As expected (DOS 5 or later), the hard drive now had the C: assignment.

The drive letter assignment was different to what the FDC-344 put on screen, proving that the FDC-344 BIOS (running early) is not well positioned to predict how DOS will assign drive letters.

All floppy drives behaved as expected. I could read data on all of them.
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
Further to my previous post.
Sometimes a CTRL-ALT-DEL would result in the display of "FDC Error !" and there was no access to the floppy drives.
A cold (hard) boot was required to fix that.
 

modem7

Veteran Member
Joined
May 29, 2006
Messages
7,789
Location
Melbourne, Australia
After realising my mistake, IBM/Xebec controller instead of Seagate ST-10, I tried an ST-10/ST-225 combination in the setup.

Power on.
After a while, the ST-10 displayed:

ST10 v2.4
Hard Drive 1: ST225


Then, the FDC-344 floppy controller displayed its block of text.
Then, the 5150 booted from the ST-225 (loaded with MS-DOS 6.22).

The ST-225 appeared as C: and I was able to read files on all three floppy drives (A=360K, B=1.2M, D=1.44M).

So, everything as expected.

To note is that I had the ST-10 jumpered for the default setting (BIOS at C8000), as pictured [here].
 

Lutiana

Administrator
Staff member
Joined
Mar 26, 2009
Messages
3,203
Location
Dublin, CA USA
What happens when you have 2 floppies and the MFM drive installed? Do all 3 work as expected (ie A: B: are floppy and C: is HDD)?
 

gerrydoire

Veteran Member
Joined
Aug 25, 2008
Messages
1,145
After realising my mistake, IBM/Xebec controller instead of Seagate ST-10, I tried an ST-10/ST-225 combination in the setup.

Power on.
After a while, the ST-10 displayed:

ST10 v2.4
Hard Drive 1: ST225


Then, the FDC-344 floppy controller displayed its block of text.
Then, the 5150 booted from the ST-225 (loaded with MS-DOS 6.22).

The ST-225 appeared as C: and I was able to read files on all three floppy drives (A=360K, B=1.2M, D=1.44M).

So, everything as expected.

To note is that I had the ST-10 jumpered for the default setting (BIOS at C8000), as pictured [here].


I'm going to try all of this and see if I can replicate the results :)
 

Anonymous Coward

Veteran Member
Joined
Aug 11, 2004
Messages
1,534
Location
Shandong, China
At least your Unique FDC controllers work. I could never get mine to work with high density drives. I tried multiple systems too. I think my BIOS might be buggered. Could you provide me with a copy of the one you are using?
 
Top