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COMPUTER BITS BY GEOFF COHEN An easy way to identify IDE hard disc parameters Losing the CMOS setup in your computer is a real nuisance if you don’t have a copy of the hard disc drive parame­ters. Diskinfo.exe is a nifty little utility program that will automatically retrieve the required disc parameters for you. This article was written in response to an earlier article entitled “CMOS Memory Settings – What To Do If The Battery Goes Flat” (SILICON CHIP, May 1995). In that article, the author described how to re-enter a PC’s CMOS setup values if they were lost. One of the things emphasised in the original article was that all PC owners should keep a record of their hard disc drive parameters for just such an eventuality. Unfortunately, not all owners do that and the relevant information is not always at­tached to the drive unit. I have been designing electronic hardware, writing software and repairing PC problems for many years now, so having PCs crash on me is no novelty. As a full-time computer professional, there are two problems that have given me considerable hassles with PCs over the past few years. These problems are: (1) what to do if the CMOS crashes with a good battery; Fig.1: this screen grab shows the information returned by the program. As well as the number of cylinders, heads and sectors per track, it also includes the drive capacity, its model and serial numbers, the buffer size and the number of bytes per sector. 72  Silicon Chip and (2) finding out the hard disc type if you do not have easy physical access to the drive itself (eg, in laptop PCs), or if the details are not attached to the drive in the first place. Why does the CMOS crash? Let’s take a look at the CMOS memory problem first. In my experience, it is not always a flat battery that causes the CMOS to crash. In fact, some motherboards are prone to losing their CMOS setup when combined with certain power supplies. As a rule of thumb, if this happens with a good battery more often than once every two months, then it’s quite possible that there is a fault on the motherboard, in the power supply or, very occasionally, on a bus card. If this is occurring with your PC and it is still under warranty, you should return it to your supplier as soon as possi­ble. Some intermittent faults can take a long time to track down, since there are usually a lot of possible causes that have to be eliminated. However, if the fault is reported to the supplier before the warranty period expires, they have to fix the problem, even if the warranty period expires before the fault is finally rectified. I have also noticed that CMOS memory problems are more likely to occur in the “el cheapo” motherboard upgrades, although this problem is not as frequent as it once was. I usually find out about it after my customer has had their old “AT” or 386 PC upgraded to a 486 and then, after it fails, can’t get it fixed under warranty, as the “el cheapo” supplier is no longer in business. Just another example of Notes On The Operation Of DISKINFO.EXE Diskinfo.exe is a C utility program written by Geoff Cohen and Alan Vidler. It retrieves the IDE hard disc details from IBM (& compatible) AT, 386, 486 and Pentium PCs, independently of the state of the CMOS or BIOS. This is useful when the CMOS is incor­rect or has no hard disc details entered, as happens with a new motherboard. The Diskinfo.exe program uses the standard ATA (IDE) disc com­mand set, sending commands to and receiving status details and textual data from the ATA disc drive. I found a lot of useful details in AT attachment interface specifications ATA2-R3.DOC, which I downloaded from the Internet before we started writing Diskinfo.exe. Alan Vidler looked at the Linux hard disk I/O source code and did most of the initial design of the program. While the complete list of commands is too long to go into, the basic operation of Diskinfo.exe is: (1). Check if the drive is an IDE type & exit if not; (2). Send the Identify Drive command; (3). Receive the details, format & display on screen; (4). Repeat steps 1-3 for Drive 1 On a more detailed level, the program first checks if Drive 0 (ie, C:) is an ATA (or IDE) drive, by sending the command HD_CURRENT (0x1f6) to I/O port A0. It then waits 20ms, checks if the ready bit (0x40) is set, and exits if it isn’t. Next, it sends the identify drive (0x1f7) command to the I/O port, waits 20ms, then reads the information returned from the ATA disc drive and displays it on the screen. This complete procedure is then repeated for Drive 1 (ie, D:), the only difference being that the commands are sent to I/O port B0 instead of A0. In addition, the message “press any key for drive D Information” appears on the screen. It is also worth mentioning that this information can be sent to a file by redirecting the output. This is done by typing (at the A:> prompt): DISKINFO>FILENAME TANSTAAFL1, I guess (1there ain’t no such thing as a free lunch). Another less frequent cause of CMOS problems is the 240V mains power. In particular, mains spikes may propagate through the power supply to the CMOS while the computer is running. This can cause an error the next time the computer is switched on but usually the PC just hangs when the spike arrives. I always recommend fitting a mains spike suppressor for every PC installation. As far as I am concerned, mains spike suppressors are like chicken soup – they may help and they cer­ tainly won’t hurt. For network and small commercial systems, a UPS (uninterruptable power supply) is a must – at least for the server. If you write programs, another source of CMOS errors is the odd program crashing when you try to run it and then going haywire. Of course, this has never happened to me; well, would you believe hardly ever? When a program runs haywire, there is a low but finite probability that it will write odd characters all through your PCs memory and this can very easily put rubbish into the CMOS memory. C and Assembler are really good at this and I have even managed to get normally well-behaved compilers to crash the CMOS, but I really had to work at it. What hard disc is it? Now we get to the difficult part – finding out what type of hard disc is lurking under your PC’s cover when the CMOS thinks you don’t have a hard disc at all. In the past, I have nearly gone mad trying to find what the hard disc parameters were on a PC (ie, the number of heads, cylinders and sectors per track). This is even more difficult if my client is in another city, as I cannot personally open the case and have a look inside. Physically checking for hard disc information has become easier of late, with most manufacturers now printing the specifi­cations on a label attached to the top of the disc drive. Of course, this is no help if you own a disc drive that doesn’t have a specifications label. And even if the information is there, you still have to open your PC to inspect it. This can take a fair amount of time on some PCs, especially if the hard disc is buried in the drive bay beneath one of the floppy disc drives and has to temporarily be removed so that the label can be seen. When servicing older PCs, I have sometimes had to complete­ly remove the hard disc from the computer, just to discover the brand and model, and then try to find the details in assorted lists supplied (sometimes grudgingly) by the hard disc manufac­turers. Sometimes, even this didn’t provide an answer and I was forced to enter the most common hard disc values into the CMOS on a trial and error basis, sometimes spending hours on the more obscure models. Diskinfo.exe Fortunately, these trials are no longer necessary, as there are now some really nifty utilities around which will retrieve the hard disc parameters from a PC, even when the CMOS is com­ p letely cleared (non-computerese for trashed). I normally use one written by myself and Alan Vidler (of AV Software), which we have placed in the public domain. Called DISKINFO.EXE, it provides details on IDE drives. These form the overwhelming majority of the small to medium-capac­ity hard disc drives sold over the last few years. In operation, the program bypasses the system BIOS and accesses the drive (or drives) directly. The disc drive parameters are then displayed on the screen. Fig.1 shows the information returned by the program. As well as the number of cylinders, heads and sectors per track, it also includes the drive capacity, its model and serial numbers, the buffer size and the number of bytes per sector. Note, however, that the software will not work with SCSI drives or with some types of caching controllers and other non-standard controllers (even if they are controlling an IDE drive). If August 1995  73 How To Make A Bootable Diskinfo.Exe Floppy When you receive your copy of DISKINFO.EXE, you will need to copy it to a bootable floppy, so it can be used if your CMOS becomes corrupted as some later date. First, go to the DOS prompt, then put the disc containing DISKINFO.EXE in floppy disc drive A and copy it to drive C by typing: COPY A:DISKINFO.EXE C:\ (or COPY B:DISKINFO.EXE C:\ for drive B. When this has finished, remove the DISKINFO.EXE floppy disc and install the floppy disc that is to become your boot disc in drive A. Now, from the C:> prompt, type: FORMAT A:/S (or FORMAT A:/S/U for MS DOS 6). When this is complete, type: COPY C:\DISKINFO.EXE A: After this is completed, you can test that the boot disc functions correctly by rebooting the PC with this disc still in drive A. When the PC has booted up, you need to press <Enter> twice to get past the time & date questions. If you now type DISKINFO at the A:> prompt, the screen should display data simi­lar to that shown in Fig.1. It would, of course, be a good idea to write this informa­tion down now, rather than after the CMOS information is lost. I always write the hard disc parameters (number of heads, cylinders and sectors per track) on a self-adhesive label and stick it to the back of the PC. a non-supported controller is found, a reject message is displayed and the program exits. Alternatively, with some caching controllers, the program will display nonsense results and fail to show the Model Number, Firmware Revision number or Serial Number. In either case, this doesn’t cause any problems since the program cannot write to the disc or alter any of its parameters. Assuming that your CMOS has crashed, the procedure is to first restore all the CMOS settings (see the May 1995 article), except for the hard disc type. This should initially be left at “None” (sometimes called “Type 0” or “No Hard Disc”). Now return to the Main Menu of the CMOS Setup utility and carefully check the menu items. Many late-mod- el PCs have an option which will automatically fill in the hard disc numbers for you. This menu item is usually called “IDE HDD (Hard Disc Drive) Auto Detect”, or someting similar. If your PC has this option, then select it and press the <Enter> key. This will run a HDD auto detect utility and will write the correct hard disc details (number of heads, cylinders and sectors per track) into the CMOS memory. You then only need to return to the Main Menu of the CMOS Setup and save these corrected settings. The PC will now reboot with the hard disc running normally. If your PC does not have this option, you will need to boot the machine from a floppy disc containing the DISKINFO.EXE utility. When you run the utility (ie, type DISKINFO at the A:> prompt), it will show a screen similar to that shown in Fig.1. Note the number of cylinders, heads and sectors per track, then remove the floppy disc, reboot your PC and again proceed to the CMOS Setup screen. This is usually accomplished by pressing the <Del> key when prompted to do so, as described in the earlier article. Now go to the Standard CMOS Setup, select Hard Disc C Fig.2: most manufacturers now print the disc drive (sometimes called Hard parameters on an attached label. 74  Silicon Chip Disc 0) and select Type 47 (may also be called “User” or “User Defined”). As indicated by the legends at the bottom of the screen, you select the entries using the arrow keys and modify the entries using the Page Up and Page down keys. The hard disc parameters that you obtained from DISKINFO.EXE (and wrote down) are now entered. This is done by selecting the relevant heading and entering the appropriate value directly via the keyboard. These headings are: Cyl = number of cylinders; Head = number of heads; and Sect = number of Sectors per track. The other two hard disc entries are not critical. I usually enter 65535 for WPcomp (sometimes called Precomp) and 1024 for Lzone (sometimes called LandZone). The Setup screen should now show the correct hard disc size underneath the “Size” head­ing. All you need to do now is to return to the CMOS Setup’s Main Menu and save these new settings. Your computer should now boot normally from the hard disc drive, just as it used to before the CMOS setup was lost. As a final point, note that if you have a SCSI hard disc, you must always choose “Type 0” for this type of drive. I have received frantic calls from customers with SCSI hard discs, asking why their PC won’t boot up after they have restored (or changed) the CMOS Setup. Despite what is in the hard disc manual, they sometimes choose a “Type 47”, often because of a helpful friend who “knows all about computers” and thinks that a “Type 0” is incorrect. Of course, when they attempt to boot up the PC, it either hangs or gives a hard disc error message. The remedy is simple – just reset the hard disc to a Type 0. Obtaining DISKINFO.EXE The program DISKINFO.EXE is available for $10 (incl. p&p) from Silicon Chip Publications (see software advert), or directly from the Author at PO Box 136, Kippax, ACT, 2615. Alternatively, you can email me at gcohen<at>pcug.org.au for a copy via the Internet. I log on to the Internet daily, or via Compuserve at 100026,307 (but I only check here once a week). I am also available at any of these addresses for anyone who has problems that they SC can’t solve on their own.