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View Full Version : C: and D: in my 5155, but there's only one physical drive.



rtwo
April 21st, 2010, 04:50 AM
I have one harddisc in my 5155 but I see two drives, C: and D: and both are the same. When I copy something to C: it also appears on D: and when renaming and deleting also.
It runs PC-Dos 3.2 and when using FDISK I can also switch between two discs.
Is this normal for these older computers??

cosam
April 21st, 2010, 05:09 AM
What does your partition table look like? Maybe you have two partitions which exactly overlap.

I wouldn't say it was normal, but I can see it being useful if software expects to find stuff on D: when there is no actual second drive or partition.

rtwo
April 21st, 2010, 05:33 AM
One active partition on the C: drive, and one partition on D:
When using FDISK and when there is more then one drive, you can switch between these drives, you get an option 5 in FDISK.
If there is only one drive, you can only check the partition table (option 4) but can't switch drives.
With my 5155 it is possible to switch between two drives but there is only one.

Marrr
April 21st, 2010, 08:41 AM
Perhaps you're using ASSIGN or SUBST commands? Check your autoexec.bat file...

Edit: come to think of it, ASSIGNed or SUBSTed drives shouldn't appear in FDISK, so it must be something else... either some weird device driver (also check your config.sys), or some mess in the partition table, worth to look at with a disk editor...
BTW: what can you see when you boot from a diskette?

rtwo
April 21st, 2010, 09:46 AM
Even when booting from a diskette and using fdisk, I see two drives, so nothing strange in config.sys or autoexec.bat.
I noticed that there is no real autoexec.bat on this pc, there is a folder c:\sys and in there is a file auto.bat, this one acts like autoexec.bat.
Dos is installed in a folder called c:\bin
I have never seen such thing before, tried to copy auto.bat to root as autoexec.bat but then it does not load, strange.
But as I said, even when booting from diskette gives me two drives.

k2x4b524[
April 21st, 2010, 10:06 AM
sounds like a mirroring configuration of some kind, did they even have raid back then?

Chuck(G)
April 21st, 2010, 10:07 AM
Check the drive select jumpers on the disk drive. It's entirely possible that your controller is seeing the same drive twice.

krebizfan
April 21st, 2010, 11:23 AM
One other possibility is a ghost from some other partitioning software or disk compression software where the "extra" drive isn't correctly hidden. I have seen a single disk showing up as two different but identical disks with such flawed setups before, though never in the partition table itself. But with so many tricky schemes in the past, I expect one might have tried a partition table hack.

In any case, back up the system and delete the partitions to start over. If the problem recurs, then you have a very interesting problem.

Chuck(G)
April 21st, 2010, 12:05 PM
In any case, back up the system and delete the partitions to start over. If the problem recurs, then you have a very interesting problem.

I'll wager a beer at my favorite watering hole that when he does that, he still gets two identical drives.

Some old MFM drives used DIP switches or pluggable headers to determine drive select. Be sure that your drive doesn't have more than one drive select configured. Also, make sure that your drive has the terminator installed if it's the lone drive--a missing terminator can also cause a phantom select.

MikeS
April 21st, 2010, 12:29 PM
I'll wager a beer at my favorite watering hole that when he does that, he still gets two identical drives.

Some old MFM drives used DIP switches or pluggable headers to determine drive select. Be sure that your drive doesn't have more than one drive select configured. Also, make sure that your drive has the terminator installed if it's the lone drive--a missing terminator can also cause a phantom select.Yeah, my money's also on a DS issue.

Before you do anything drastic like playing with the partition table check those DS jumpers or switches and also the cables and connectors; are the cables straight through, i.e. no twists or anything else unusual, and is the terminator installed properly?

Any idea what make/model the drive is?

barythrin
April 21st, 2010, 01:53 PM
Are you sure about the autoexec.bat and config.sys not being there? config.sys is a system file so may be hidden and perhaps a user hid autoexec.bat also. You might see them if you do dir /a (for all files). I don't think I've ever seen a drive show up like you're describing. Possibly a corrupt partition table that has both partitions pointing to the same FAT? What other programs load when the computer starts? I know stacker (haven't used it in 12+ years) creates a second drive letter which can seem confusing but again I don't recall the data being the same.

k2x4b524[
April 21st, 2010, 08:55 PM
but why would the same partition table be showing up on 2 drives, writing the exact same data to both? This one's outta my league, but drive select may be the culprit. If it is, you've found a good way to mirror data on an mfm drive..

MikeS
April 22nd, 2010, 09:22 AM
but why would the same partition table be showing up on 2 drives, writing the exact same data to both? This one's outta my league, but drive select may be the culprit. If it is, you've found a good way to mirror data on an mfm drive..I think you've misunderstood; I think there's only one actual disk drive but the OS sees it twice, as C and D. ST412/506 type drives have four drive select lines (same as floppies) and jumpers or switches that determine which line the drive will respond to, and normally only one of these jumpers would be selected on the drive. But if DS0 and 1 (C and D) were both jumpered, or there were a short between those two lines in the cable or a connector then the drive would respond to both C and D; also, if the terminating resistor is missing it's possible (although unlikely) that the drive would always be selected and respond to any request regardless of drive number/letter.

Less likely is a fault in the drive that lets it ignore the drive select signal or effectively short the two internally, or something in the OS that directs requests for both C and D to the same select line.

rtwo
April 24th, 2010, 01:26 PM
Thanks guys for all you replies.
No special software or drivers are loaded, config.sys is clean and so is auto.bat (I'll come back to that issue later) and no stacker software, used to use that myself ages ago ;). Booting from a clean disk and using fdisk shows me 2 drives also.
So first I have to check my hard drive for jumpers and/or switches and the terminator resistor. Are those switches marked on the drive, or do I need to have a manual to find out, I don't know what brand/type drive it is, will remove it tommorow to check, and how does that terminator resistor looks like. I know it is easier for you to answer these questions when you know what drive is in there, I'll let you know asap.

auto.bat issue
PC-Dos 3.20 is installed in a \bin folder. In root there is a config.sys, in a \sys folder there is a file called auto.bat (not autoexec.bat). When moving auto.bat to root it wont load on reboot, when renaming it to autoexec.bat in root, it wont load. When renaming it to autoexec.bat in \sys folder, it wont load, so it only loads when it is placed in \sys as auto.bat. There is nothing in config.sys that redirects to \sys ot whatsoever. I know you can do such things with NDOS or 4DOS, but that is not installed. This is NOT normal behaviour for PC-Dos 3.20, is it??, anyone any idea why/how/what?

One more thing, got a second 5155 today, not as nice as the one I have now, but hey, it was cheap.
The second one has the original intel 8088 processor in it, my first one has a Nec V20 in it.
What do you guys think, keep the Nec V20, or replace it with the Intel 8088 for autenticity reasons.
Second one has a 10mb disc in it, (my first has a 20mb disc), I want to know when the 5155's are manufactured but cant find dates on them, I noticed both are 64k-256K motherboards, both hacked up to 640k, the second one has a soldered jumper on it, my firts one is missing the jumper.

Chuck(G)
April 24th, 2010, 02:03 PM
I can offer you things to check if you can identify the hard drive in your 5155. (Note: There was, to the best of my knowledge, no standard IBM HD option for the 5155, so you could have just about anything in that position. I've seen a 5155 with a SCSI drive, for instance).

Keep the V20. In addition to being somewhat faster than the 8088, it uses less power and supports many 80286 instructions (more things will work on your system). On the other hand, if you want to be "authentic", put the 8088 in and have the whole thing bronzed and put it in a glass display case. If it were my system, I'd put the 8088 in some antistatic foam and put it in a bag and tape it inside the case for safekeeping. That way, nothing gets lost.

modem7
April 24th, 2010, 02:38 PM
Second one has a 10mb disc in it, (my first has a 20mb disc), I want to know when the 5155's are manufactured but cant find dates on them, I noticed both are 64k-256K motherboards, both hacked up to 640k, the second one has a soldered jumper on it, my firts one is missing the jumper.
The 5155 was released in February 1984 and withdrawn April 1986. The 5155 uses a 5160 motherboard, with the first units having 256K RAM fitted. No hard drive was supplied. The date codes on the motherboard chips should give you a rough indication of the date-of-manufacture of your units.

Raven
April 24th, 2010, 05:45 PM
Just because the NEC V20 didn't come with it doesn't mean it isn't "authentic" - as long as it's an era-appropriate upgrade it's still authentic in my book - i.e., you aren't shoving a modern PCI video card (like a GF6200 or something) into a 486.

NeXT
April 24th, 2010, 06:08 PM
Have you checked for a drive splitting option on the hard disk?
My Equity II and it's 40mb MFM drive for the longest time thought it had two 20mb drives until I found out that you could split the drive into two by means of a jumper on the drive. After I removed the jumper I was able to reformat the drive as a single 40mb drive.

MikeS
April 24th, 2010, 11:28 PM
Have you checked for a drive splitting option on the hard disk?
My Equity II and it's 40mb MFM drive for the longest time thought it had two 20mb drives until I found out that you could split the drive into two by means of a jumper on the drive. After I removed the jumper I was able to reformat the drive as a single 40mb drive.But did the drives mirror each other as the OP states in his first post ? I.e. did what you wrote to C also appear on D?

rtwo
April 25th, 2010, 10:45 AM
Ok, had to remove almost everything from my 5155 to get to the harddrive, but I now have the model. It is a Microsience HH-725 made in Singapore dated 1987, it is a 20MB drive, so that is correct. It has one switchblock with 10 dipswitches on it. Switch 3,4 and 10 are up. I found the following on the internet:
SW1
---

+------------------------------+
|+-++-++-++-++-++-++-++-++-++-+|OFF (0)
||x||x||x||x||x||x||x||x||x||x||
|+-++-++-++-++-++-++-++-++-++-+|ON (1)
+-1--2--3--4--5--6--7--8--9--10+
Drive Select 1 --+ | | | +--+--+--+--+ +-- Exerciser
Drive Select 2 -----+ | | Termination
Drive Select 3 --------+ |
Drive Select 4 -----------+

It looks like switch 1 and 2 are on, thus drive 1 and 2 selected, could this be my problem? Termination switches all on.

About the auto.bat, anyone out there who knows what causes this strange issue??

wmmullaney
April 25th, 2010, 10:52 AM
Try it with just the first drive select, that should fix it.

rtwo
April 25th, 2010, 11:49 AM
Switched drive select 2 off, and voila, only one drive visible, C: drive with 20MB disk space.
Created a bootdiskette and copied config.sys and auto.bat to autoexec.bat on diskette, booted from diskette and both config.sys and autoexec.bat where executed. I need to find a clean PC-Dos 3.20 diskette so I can reformat the disk, and install PC-Dos on it, my guess is that the strange auto.bat issue will disapear also.
Anyone knows where I can get (download) PC-Dos 3.20???

Chuck(G)
April 25th, 2010, 12:58 PM
You're welcome.

Yes, you can simply boot from a PC-DOS diskette and FORMAT /S C: and then copy whatever you'd like to the drive.

sombunall
April 25th, 2010, 08:21 PM
I would like to add that I changed a jumper on a floppy connected as B drive on the cable from DS2 to DS1. I saw only an a: drive and when a read from it it would access both a: and b: at the same time even down to the head movements. I thought it was related somehow...

Chuck(G)
April 26th, 2010, 12:52 AM
I would like to add that I changed a jumper on a floppy connected as B drive on the cable from DS2 to DS1. I saw only an a: drive and when a read from it it would access both a: and b: at the same time even down to the head movements. I thought it was related somehow...

It is--you can get the same effect by jumpering both DS1 and DS2 for a floppy. Probably make a huge mess of things when doing a copy A: B:

rtwo
April 29th, 2010, 01:31 AM
It looks like the prior owner of my 5155 had put a customized version of pc-dos 3.2 on this machine. I got my hands on a new 3.2 version, reformatted my drive and everything is working as it should be. My 5155 is working, as brand new, it even looks like new.
Thank you all for your help..