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IBM PC AT CMOS Battery Trouble

risko404

Member
Joined
Dec 22, 2010
Messages
15
I just recently recieved an IBM PC AT Computer in the mail. It turns on and tries to read from the floppy disk drives and hard drive but the cmos battery is dead. It gives me error 161 and says to enter setup. The people on ebay told me it was dead so I bought it thinking I could find the cmos bettery on the motherboard. Well, I have had no luck finding anything that looks like a cmos battery. I have no idea what a cmos battery looks like in an IBM AT so I need someone to tell me what it looks like, or just send me a picture, or tell me where it's located. There are many little chips on the mobo but I can't seem to find out which one it is, or maybe its attached somewhere in the case that I can't see. If someone could help me with this, I would be very grateful. Also could someone tell me what I press on the keyboard to enter the setup on an IBM AT, because I couldn't figure it out. Thanks.
 
There is no battery on the IBM-AT 5170 Mainboard. There are only pins near the keyboard connector for an external battery. To enter the setup you need the IBM-Diagnostics diskette. There is no build in bios-setup.
 
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so if there is no battery built in for the IBM PC AT, what type would i need to buy? also, my ibm at has a 20mb full height 5.25 hard drive, but it doesn't boot from it, it won't boot from a dos floppy either. what should i do to get this thing to work?
 
so if there is no battery built in for the IBM PC AT, what type would i need to buy?

Look for a Rayovac 844 or equivalent 4.5 volt Lithium battery. Actually any non-rechargeable battery between about 4 and 6 volts can be used, as long as it has the widely spaced 2-wire connector for the motherboard.

Prices vary widely; this one is about as cheap as I could find:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370420937872

Or you can use a 3 or 4 AA cell battery holder and just put in regular AA batteries, as a cheaper alternative.
 
Our Wiki has an entry for the IBM AT. It contains details of the battery.
http://wiki.vintage-computer.com/index.php/IBM_PC_AT_(5170)
That Wiki entry may also contain other information about the IBM AT that you will find useful.

Also could someone tell me what I press on the keyboard to enter the setup on an IBM AT, because I couldn't figure it out. Thanks.

There a few methods of restoring the IBM AT's setup. Which one you use will probably depend on your abilities and the resources at your disposal. Four possible methods follow.

* Use the 'IBM Diagnostics for the IBM AT' floppy (as already mentioned by Matel).

* Create a 5.25" boot floppy that contains the GSETUP.EXE program. Boot from the floppy then run GSETUP. GSETUP is available at http://members.dodo.com.au/~slappanel555/software/GSETUP.ZIP

* Use the procedure at http://members.dodo.com.au/~slappanel555/5170_gsetup.htm This involves temporarily connecting a 1.44MB drive.

* When the IBM AT boots in BASIC, type in some BASIC code. We have a Windows program that will generate the required BASIC code for your AT's particular setup. Detailed at http://www.vintage-computer.com/vcforum/archive/index.php/t-15197.html

also, my ibm at has a 20mb full height 5.25 hard drive
That will no doubt be an IBM type 2 drive. Whichever setup method you use, you need to specify "2" as the hard drive type number.
 
well i replaced the battery and i made the generic setup boot disk with a 5.25 floppy disk but when i tried to boot the ibm at with it, there was an error that said non-system disk replace disk and press any key. i tried using a formatted 360k floppy and then i formattted a disk as 1.2mb and then putting the gsetup file on it, but it still didn't work. can someone tell me how i'm suppose to do this because i don't know what else to do.
 
Do you have another system that runs DOS? If so, what happens when you format a 360K disk in system mode? That is, using something like:

FORMAT /S A:
 
I'm sure Chuck intended:
FORMAT A: /S

Actually, on my system, it works either way. I've gotten into the Unix habit of putting switches first, then the object term. But at least on MS-DOS 7.0, you can do stuff like:

FORMAT /S A: /F:720

and it'll still work. Maybe that's not true on early versions of DOS, however.
 
Do you have another system that runs DOS? If so, what happens when you format a 360K disk in system mode? That is, using something like:

FORMAT /S A:

The /S (or any other switch) has to go after the drive letter, not before it.
 
Depends on the version of DOS you're using. (see posts above). On later versions of DOS switches can go before or after the drive letter--or both.

Although the /? help in Windows XP still indicates that the drive or path should go first, it seems MS modified the command line parsing to allow more flexibility, such as "DIR /W C:\WINDOWS". However, it's still best to follow the "traditional" syntax, so your commands have more chance of working correctly on older versions of DOS or Windows.
 
Although the /? help in Windows XP still indicates that the drive or path should go first, it seems MS modified the command line parsing to allow more flexibility, such as "DIR /W C:\WINDOWS". However, it's still best to follow the "traditional" syntax, so your commands have more chance of working correctly on older versions of DOS or Windows.

Yes, and 20 years ago, I might have done just that. But increasingly, I find myself using programs that are either ports to Windows of *nix programs or using *nix itself, which expects to see switches before the command-line arguments. Indeed, even hoary old Microsoft C for 16-bit platforms demands that you put the switches before the source file name--and that's on a program that was written by Microsoft for DOS that claims a copyright going back to 1984!

I'll have to verify when Microsoft got religion. I suspect the old way still obtains with DOS 4.0, but changes at DOS 5. I'm surprised that they didn't do it at DOS 2.0, when they undertook "the great Xenix-ification" of DOS.
 
well i got a battery and duck taped it inside of the case, and plugged it up to the mobo. apparently it works because i can now boot from a dos 3.30 floppy but c: isn't recognized as the hard drive. i also was able to put in the floppy with gsetup.exe on it and it opened the setup program. so now i need someone to guide me through the process to get the hard drive working again. as i said before, i have a full height 5.25 hard drive, the sticker on it says it has a capacity of 20mb, and it turns on when i boot up the pc. i am suspecting that the floppy drive on the bottom of the pc, (below the floppy drive with a circle and a star on it) is dead. because whenever i put a floppy disk in it, it gives me the following error: General Failure error reading drive B. that happened when i put a 360k floppy disk in it. the floppy drive above it, (the one with the circle and star symbol on it) reads my 360k floppy disks just fine. the problem is i don't know which drive is the 360k drive and which one is the 1.2mb drive. if someone could help me setup my hard drive and identify my floppy drives, i would greatly appreciate it.
 
i think i might need to clean the floppy drives in my ibm at because they leave some dust on my disks when i take them out and sometimes i have to blow inside of the drive to get the floppies to read, could someone maybe send me a link to a tutorial about cleaning an ibm at's floppy drives? thanks.
 
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