Conference noted::ibmpc-95

Does 1.00.13.AX1T support hard drives larger than 2Gb?  I currently have
1.00.09.AX1 on my P5-90 and would like to install a new drive, perhaps in
the 3Gb range.

Jeff

>>>Does 1.00.13.AX1T support hard drives larger than 2Gb?  

Yes, but your motherboard may not. The 1.00.13.AX1T BIOS supports three
addressing modes:

1) CHS           - The original Cylinder/Head/Sector method (~524MB max I think)
2) Logical Block - LBA method (My tests show it's only good to 2.1GB [4095 cyl])
3) Extended CHS  - This method correctly sized my 5.1GB drive [9022 cyl]

However, even though the BIOS correctly sized my 5.1GB drive using "Extended
CHS", something on my motherboard (Plato MB w/Nepture chipset) couldn't handle
the large drive and limited me to a drive size of 2.1GB (I verified this by
checking out the Intel Motherboard website). 

Bottom line: Just because the BIOS supports large drives, doesn't necessarily
mean it will work. Make sure your motherboard can handle it too.

In my case, I ended out using the EZ-Drive (Dynamic Overlay) which breaks my
drive up into 2.1GB max chunks so that my MB can swallow them.

-Craig

    re .4:
    
�However, even though the BIOS correctly sized my 5.1GB drive using "Extended
�CHS", something on my motherboard (Plato MB w/Nepture chipset) couldn't handle
�the large drive and limited me to a drive size of 2.1GB (I verified this by
�checking out the Intel Motherboard website). 
    
    Can you give a pointer to the info? I'd be curious to know what
    motherboard feature(s) could prevent me from using a >2GB drive (I'm
    planning to get one soon). In fact I can't think of any way the
    motherboard could limit it - isn't it all just a matter of the BIOS
    (� any BIOS bugs), and software (your OS - Windows 95 retail version
    can only handle disks 4GB, and partitions up ti 2GB I believe).
    

>>> Can you give a pointer to the info? 

I can't find the original Intel Motherboard note (it probably expired) but 
there are others. Check out:

             http://cs.intel.com:80/Intel/motherboards/msg00888.htm

Here's an excerpt:
------------------------------------------------------------------------------
The Premiere/PCI II motherboard, commonly referred to as 'Plato', does
not support IDE hard drives larger than 2.1 GB. Some hard drive
manufacturers supply a utility that allows the full capacity of the
hard drive to be accessed. Please contact your hard drive manufacturer
for additional information.

Brian
Intel Technical Support
------------------------------------------------------------------------------

>>>I'd be curious to know what
>>>motherboard feature(s) could prevent me from using a >2GB drive (I'm
>>>planning to get one soon). In fact I can't think of any way the
>>>motherboard could limit it 

I have no idea what part of the Plato MB limits the IDE drive to 2.1GB, but I
can think of some posibilities. For example, let's say the PCI-IDE controller
chip on the Plato MB has a 12-bit cylinder register. That would limit the
cylinder # from 0 to 4095. Even though the BIOS correctly translates a 9022 cyc
disk access using extended CHS, The cylinder # gets truncated when travels from
the PCI to the IDE bus. 

After all, if an ASIC designer was told that the system didn't need to support
more than 2.1GB drives, it's unlikely she/he would implement any more logic
than necessary. I wouldn't. Apparently the designers of the Plato MB didn't
either. 

When I first installed my 5.1GB drive, I tried like crazy to make my system
see it properly without the use of a DDO (Dynamic disk overlay). After that
lesson in futility, I surfed the net for answers and I'm convinced that
the "Intel Technical Support" personel know of what they speak.

-Craig

    re .6: Ok, I didn't think about the on-board controller... still sounds
    strange, I've never heard the controller being a problem. How would the
    disk manager software make things look different to the controller (as
    compared to what the BIOS does)?
    

    There is NO cylinder register on an IDE controller.  It's on the IDE
    disk drive.
    
    An IDE controller is not much more than a bunch of buffers and address
    decode logic.  All the registers are in the drive.
    
    This is why there is a distinction between master_no_slave vs
    master_with_slave_present.  The master drive needs to know if it should
    respond when a register is read.  There is usually a strap on the
    master to tell it.
    
    Slaves respond when the drive select bit is set one way.
    
    Masters respond when the drive select bit is set the other way.
    
    Masters respond in both cases if there is no slave drive present.
    
    When actually asked to do work, only the selected drive does anything.
    
    Steveg

re .7: How would the disk manager software make things look different to the
       controller 

I don't understand the details, but basicly the EZ-Drive DDO hooks into 
Int 13h ROM BIOS call and replaces the ROM BIOS CHS translation with its own.
It plays games with the true number of Cyl,Heads,Sectors of the drive versus
the number of Cyl,Heads,Sectors it tells DOS/system. In my case it tells DOS
that my drive has 255 heads. It never lets the system see more than 4095 cyl. 
Bottom line is that my system it happy to see 3 drives; a 2.1GB drive C:,
a 2.1GB drive D:, and a 900MB drive E:. However, if I boot DOS off a floppy, it
can't see my 5.1GB drive unless the DDO is loaded first. 

re .8: buffers vs registers

OK, but my only point was that somehow the cyl # needs to get from the CPU to
the IDE drive. The field that holds this variable needs to be 14 bits wide to
support a 5.1GB drive directly. My motherboard HW truncates this to 12 bits
somewhere between the CPU and IDE Drive. and that's why I can't use extended
CHS to map my drive. Whether the pins, etch, buffers, or registers limit the
cyl # field to 12 bits, I don't know (or care). 

I was just trying to warn folk: "even though your BIOS can reconize a large
drive, you may still be limited by your motherboard HW". I was. Using a DDO
was my only solution.

I don't know....

I also believe the motherboard IDE interface is little more than a data
path, i.e., buffering electrons, no "smarts" that could mess it up.

It's all up to either the hard drive itself, or the BIOS or OS.  If your
motherboard truncates the field to 12 bits, I think it must be happening
in its BIOS. If the BIOS claims to support larger disks but doesn't, then
perhaps they messed up the BIOS implementation.

    
    I ran into a glitch recently. I have Arcada backup for W95 and when I
    added the patch to go to 1.1 from Seagate my performance went down,
    video started to get a bit slower, etc...I am using OnTrack Disk
    Manager for a Quantum 1280 EIDE drive. I used it for all 4 partitions
    on the drive and am now considering using BIOS as I found out from the
    previous owner it supports the bigger drives (shows LBA in WinBIOS,
    etc...). My concern is this:
    
    If I just reformat C: and do NOT use OnTrack will I run into problems
    on the other partitions? If so, I will then have to reformat them
    through normal DOS format command, correct?
    
    Now, If I go through these hoops (I was thinking of reinstalling
    software again due to running low on C: as it is and reinstalling them
    to D: to conserve on C: a bit. If I have my partitions on tape, can I
    do a restore of the other 3 partitions D-F without running into
    trouble? I know I can't restore C: due to the backup having the overlay
    hidden file there to reroute the BIOS calls for the mapping of the
    drive. I was hoping to do this as painless as possible, and it will be
    a bit more work to reinstall everything all over again due to having to
    dig for the cdroms, archives, etc...of whatever I have on it! And also
    have to reset my browser back up again to reconnect to the web through
    my provider.
    
    Thanks in advance!
    
    

A big problem for your whole scheme:  Boot sector large drive support like Disk
Manager don't work on a per-partition basis.  They apply to the entire drive.

I think you have two choices:

1)  Cross your fingers and hope that just maybe the BIOS's LBA support uses the
same scheme as Disk Managers.  Find out by setting the BIOS for LBA and the
correct parameters for your drive and booting from a floppy (not using the "hit
space now to boot from floppy" that Disk Manager does, but actually booting
directly from the floppy without having the hard disk involved).  If you can
access all the partitions on the hard drive you are in luck!  "All" you should
need to do is figure out how to refresh the boot sector on the hard drive to
remove the Disk Manager (not easy!).

2)  Back up everything, change the BIOS as above, blow everything away and
re-init the disk, restore everything.  Again, it will be difficult to actually
expunge all traces of Disk Manager.   Ontrak may be able to tell you how to do
it reliably for either case 1 or 2.

Burns

    Just to stir things up a little...here is something else you may want to 
    check into further before plunking down your hard-earned cash for a big
    EIDE disk drive...
    
    
    PCI EIDE Controller Flaws Discovered
    
    
    BY ROEDY GREEN 
    
    
    
    Introduction
    
    There are serious flaws affecting about one-third of all PCI
    motherboards. The flaws affect any motherboard or EIDE controller
    paddleboard containing the PC-Tech RZ-1000 PCI EIDE controller chip or
    the CMD PCIO 640 PCI EIDE controller chip.
    
    The flaws affect motherboards from ASUSTeK, AT&T, DEC, Dell, Gateway,
    Intel, Micron, NEC, Zeos and others. Since Intel makes so many of the
    motherboards sold under other brand names, the flaws affect many
    machines, both 486 and Pentium PCI.
    
    The flaws show up most frequently when you run a true multitasking
    operating system such as OS/2 Warp or NT. They also show up under
    Windows For WorkGroups in 32-bit mode during tape or floppy backup and
    restore. In theory, the flaws could do damage under DOS, DESQview,
    Windows and Windows For WorkGroups in 16-bit mode, but so far there
    have been no damage reports. Windows-95 contains code to bypass the
    flaws.
    
    The RZ-1000 has two flaws. The CMD-640 has those same two flaws, plus
    three others. To make matters worse, most motherboard manufacturers
    using these two flawed chips connected them up incorrectly. There are
    software bypasses for these flaws. However, the Warp fix for the
    CMD-640 reduces performance by 50 percent.
    
    What are the symptoms? 
    
    When you are using an IDE or EIDE hard disk attached to the EIDE
    motherboard port, the flaws subtly corrupt your files by randomly
    changing bytes every once in a while. The flaws introduce bugs into EXE
    files, subtle errors into your spreadsheets, stray characters into your
    word processing documents, changes to the deductions in last year's tax
    return files, and random changes to engineering design files.
    
    This corruption happens when you are simultaneously using your EIDE or
    IDE hard disk and some other device, most commonly the floppy drive or
    mag tape backup. The same sort of problem may occur on reading a CD-ROM
    drive attached to an EIDE port.
    
    Unfortunately, correcting the problem just stops further file
    corruption. It will not help to clean up the existing damage to your
    files. Right now, the focus is on bypassing the flaws. Preventing
    further corruption is child's play compared with the nightmare of
    trying to track down all the existing random errors in files. Backups,
    even from day one, may be corrupt. If you have either of the flawed
    chips, you will probably never be able to completely eliminate the
    effects of past corruption.
    
    
    Testing For The Flaws 
    
    I wrote two test programs that run under DESQview, Windows, Windows For
    WorkGroups, Windows 95, NT and OS/2. EIDEtest verifies that your hard
    disk is working properly, and CDtest verifies your CD-ROM. If these
    tests fail, it proves you have a serious problem, but not necessarily
    that you have the RZ-1000 or CMD-640 chip.
    
    If the tests pass, you still may have a problem since, especially under
    DOS, DESQview and Windows, the flaws may only show up rarely. If you
    run the tests under Windows 95 they will always pass, even if you have
    the defective chip, because the operating system already bypasses the
    flaws.
    
    What Can You Do If You Have A Flaw? 
    
    Pester the manufacturer. Unfortunately, the EIDE controller chips are
    soldered in. The only way to repair a flaw is to replace the whole
    motherboard, recycling the socketed chips: the CPU, DRAM and SRAM
    cache. It would be very expensive for computer and motherboard
    manufacturers to fix a flaw.
    
    Buy a new, unpopulated Triton PCI motherboard and recycle the CPU, DRAM
    and SRAM cache chips from the old motherboard.
    
    Run the controller in degraded mode. Some BIOSes have a feature to
    disable the EIDE prefetch buffer. Vendors may offer a BIOS upgrade to
    allow you to manually disable prefetch. The BIOS may also turn it off
    automatically if either of the defective chips is present. This will
    bypass both RZ-1000 flaws and two of the five CMD-640 flaws.
    
    Buy a PCI EIDE paddleboard controller, such as the Promise 2300+ or the
    BusLogic BT-910, to replace the one on the motherboard. You must
    disable the EIDE controller on the motherboard. This fix will waste one
    of your precious slots. Be careful. You could be leaping out of the
    RZ-1000 frying pan into the CMD-640 fire, since paddleboards often use
    the CMD-640.
    
    Buy a SCSI hard disk and CD-ROM, and avoid using the EIDE ports
    entirely. Under OS/2 and Linux, SCSI gives better performance, but
    costs more. DOS, Windows, Windows For WorkGroups and Windows 95 are
    unable to exploit the advanced features of SCSI, but at least avoid the
    EIDE flaws when you go to pure SCSI.
    
    Find a software work-around. There are fixes for Warp to bypass all the
    flaws in the RZ-1000 and CMD-640. Fixpack 5 and pre-release Fixpack 9
    do not bypass the flaws. Now that Intel and IBM have revealed the
    technical details, all the operating system writers can patch their
    EIDE drivers to bypass the flaws. There are also fixes for NT 3.1 and
    3.5.
    
    Get a BIOS upgrade. For DOS, DESQview, and Windows 3.1, to bypass the
    flaws you may need a new BIOS: an EPROM chip. If you have a flash BIOS,
    you can update it simply by downloading a file. Most BIOSes already
    have code to bypass the flaws for DOS, DESQview and Windows. However,
    more advanced operating systems bypass the BIOS, so even a smart BIOS
    will not protect you. However, the BIOS CMOS settings may allow you to
    disable prefetch, which also protects you in even true multitasking
    operating systems.
    
    
    Cut the trace. Cut the trace on the motherboard from the floppy
    changeline to the EIDE controller. However, this only bypasses one of
    the CMD-640's five flaws and one of the RZ-1000's two flaws.
    
    Whatever method you use to bypass the flaws, retest with EIDEtest and
    CDTest afterwards to be sure your fix worked and you caught all the
    problems.
    
    Cleaning Up The Mess 
    
    Once you have bypassed the flaws, you can start working on the problem
    of cleaning up your files.
    
    The first thing to do is to re-install your operating system and all
    your application programs. This will replace any damaged EXE and DLL
    files.
    
    Catching errors in your data files is more difficult. Keep your eyes
    peeled for any improbable spreadsheet results. You may have to hire a
    programmer to write you some comb programs to sniff through your
    databases, looking for suspicious values.
    
    If you routinely use the verify feature of Lotus Magellan, it can
    detect changes to files that should not have changed. This may help you
    uncover some of the damage. The flaws are not polite enough to redate
    the files they corrupt. :-)
    
    If you have backups from before the time you bought the faulty machine,
    you can restore them and re-key everything.
    
    Most people will not be so fortunate. All their backups will also be
    corrupt.
    
    Most people with flaws will just have to put up with random errors
    dotting their data files ever after.
    
    What Are the Flaws? 
    
    IBM confirmed the RZ-100 has two different flaws:
    
    In prefetch mode, multi-sector reads often fail.
    
    The chip erroneously responds to floppy status commands and corrupts
    the hard disk or CD-ROM I/O in the process.
    
    IBM confirmed the CMD-640 has five different flaws. It has the same
    prefetch problem as the RZ-1000. It has the same floppy status problem
    as the RZ-1000. It does not support simultaneous I/O on the primary and
    secondary EIDE ports. There is confusion over legacy and PCI mode.
    Finally, it does not support 32-bit writes.
    
    Test Programs 
    
    When requesting files on the Internet,you must generally use lower
    case.
    
    Below are the addresses for Roedy Green's EIDEtest and CDTest programs
    for DOS, DESQview, Windows, Windows For WorkGroups, Windows 95, NT,
    OS/2 and Warp. By the time you read this newer version, I will likely
    have posted newer versions. 
    
    ftp://garbo.uwasa.fi/pc/diskutil/
    
    ftp://ftp.cdrom.com/.4/os2/incoming/eidete16.zip
    
    Intel's RZ-1000 chip detect program:
    
    http://www.intel.com/procs/support/rz1000/rztest.exe
    
    Intel's CMD-640 and RZ-1000 chip detect program, coming soon:
    
    http://www.intel.com/procs/support/ctrltest/
    
    IOTest from PowerQuest, the makers of Partition Magic, a Warp test for
    the flaws.
    
    http://www.powerquest.com/download/iotest.zip
    
    Fixes
    
    Warp bypass for the RZ-1000 chip flaws:
    
    ftp://service.boulder.ibm.com/ps/products/os2/fixes/v3.0warp/english-us/pj19409/pj19409.zip
    
    Warp bypass for the CMD-640 chip flaws:
    
    ftp://ftpos2.cdrom.com/pub/os2/drivers/cmd640x.zip
    
    Microsoft Windows NT 3.1 ATDISK.SYS fix for the CMD-640 chip:
    
    http://www.microsoft.com/KB/softlib/mslfiles/pciatdsk.exe
    
    Microsoft Windows NT 3.5 fix for the CMD-640 chip:
    
    CMD's BBS at (714) 454-1134. 
    File 640XNT35.ZIP 
    
    Essays
    
    Roedy Green's FAQ (Frequently Asked Questions) a 19-page unabridged
    version of this article. 
    
    ftp://garbo.uwasa.fi/pc/diskutil/eidete16.zip
    ftp://ftp.cdrom.com/.4/os2/incoming/eidete16.zip
    
    PowerQuest essay:
    
    http://www.powerquest.com/
    
    Intel's FAQ
    
    http://www.intel.com/procs/support/rz1000
    
    PC-Tech's essay:
    
    http://www.mei.micron.com/rz1000/rz1000.txt
    
    Catch Pat Duffy's ([email protected]) essays each Sunday in:
    
    comp.os.os2.misc, comp.os.os2.setup.misc, comp.os.os2.setup.storage and
    comp.sys.ibm.pc.hardware.misc 
    
    Check out Pat Duffy's Web site at: 
    
    http://warp.eecs.berkeley.edu/os2/workbench/work.htm
    ftp://ftp.netcom.com/pub/ab/abe/
    
    Roedy Green is a computer consultant who prefers to work on Forth, C++,
    Delphi, DOS, OS/2 and Internet Web projects. If you send $5 (US or
    Canadian) to cover duplication, postage, and handling, he will send you
    a diskette containing the relevant test programs, fixes, Internet
    postings and essays. Send email to: [email protected] or discuss this
    problem on the Internet newsgroup in: comp.os.os2.bugs.
    
    You can also write via snail mail:
    
    Roedy Green, Canadian Mind Products #601 - 1330 Burrard Street,
    Vancouver, BC CANADA V6Z 2B8 (604) 685-8412
    
    

    
    re: .12
    
    Thanks for the info. Under #1 I will probably just have to enable it as
    I think I accidentally did that (detect hard disk) awhile ago. To
    remove OnTrac(k) I think I should only have to remove the hidden
    overlay file and remove it from the config.sys/w40 files *if* this
    works. I will be redoing the disk anyways in the next 2-3 weeks as I am
    going to include it when I sell the motherboard to a relative and go
    straight SCSI on the coming Pentium clone motherboard. I think I should
    be able to restore my DOS games and such on one partition to the SCSI
    with no problems at that point. I just have a lot of things to look at
    as far as software is concerned on my C: drive to see what I have on
    there and what I want to reload onto the new setup.
    
    If I have DOS 6.22 on there as well as W95, which fdisk do I use? It
    was prepped under DOS when I did the installation(s), ie DOS, the
    loaded W95, and other packages later. If I use DOS fdisk I lose W95
    info on the boot sector. What will happen if I go into W95 and drop to
    a DOS prompt and run its fdisk? Will I still be able to abort W95 boot
    and have my DOS 6.22 loaded instead? That is an interesting question as
    I don't think I've read it in here, nor know anyone who's done this!
    
    Thanks!
    
    Mike
    

    For infomation that I've heard, you should fdisk and format with DOS
    6.22 and not Win95 versions. There's not problem later on loading
    Win95, but you will have problems with the Win95 version of fdisk.
    
    Also, I've noticed that ever thought you never enable doublespace, if
    you boot the system and select the step-by-step approach, you'll get
    the question about loading doublespace as the first question.
    
    regards,
    
    glen kelley