Reference Disk Trivia

Reference Disks (refdisk downloads - RAW IMA format)


Create Refdisk/Diags from EXE
   Under OS/2
   Under DOS
DIR Under MS-DOS Mode Win NT/9x
Restoring Special Byte Code
Refdisk Requires Cold Start
Can the Wrong Refdisk Damage My PS/2?
Copying Option ADFs CORRECTLY
Accessing Advanced Diags from the Refdisk
Functions and Relationship of COMMAND.COM and CMD.COM
SC.EXE Trivia
   Running SC.EXE from HD
Common Refdisk Files

Create Refdisk/Diags from EXE

Note: This method doesn't apply if you grab your disk image HERE.

Download the file (rf*.exe for refdisk, rd*.exe for diags) onto your hard disk. Put a blank, formatted 1.44 MB floppy (caution, some options or early refdisks use 720 KB disks) into A:. Then run the executable and follow the instructions...

Under OS/2

  1. Run the self-executable. The following messages will appear:

    Self-extracting diskette image processor (OS/2), Version 1.03
    Please enter a drive letter compatible with a 1.44M 3.5" disk,
    or press ESC to quit:

    At this time, enter "a" for your A drive, or "b" if you have a 1.44MB B drive) and press ENTER to continue.

  2. This screen pops up:

    Press ENTER to continue...

    Repeats four or so times.

  3. Watch for this line! It will dump you out if you only hit enter.

    If you agree, type Y and press ENTER...
  4. Next it prompts you to do the following actions:

    Insert a blank high-density diskette in drive A:.
    Press ENTER to extract, or ESC to exit -
  5. Wait until the following screen appears:

    100 percent
    Extraction Complete
  6. And finally the following screen will appear:

    Press "Y" to do another copy:

    Just hit enter to end this program if you don't need another copy.

Under DOS (and compatible Windows versions)

The procedure is mostly the same, but if you don't want to use the first floppy drive, you have to specify the target drive at the command prompt. Eg.:

rf90954a.exe b:

The first screen is then confirmed simply by pressing ENTER.

DIR Under MS-DOS Mode Win NT/9x

I have created MANY ref/diags disks with W95/NT 4.0 using Windows Explorer/NT Explorer, and NONE of them refused to work. Just double click on the file, and the DOS window pops up. Do NOT do a "DIR" under MS-DOS mode! If you want to surf through the new refdisk, close the MS-DOS window and return to Explorer.

Note: Microsoft uses a 8 byte block on the diskette for labeling purposes in Win95. During execution of the "DIR" command, this 8 byte block is written to by Win95.

IBM uses this same 8 byte block on the diskette for ID purposes. Write protecting the diskette prior to the "DIR" command has shown to safeguard against this exposure. Or, you could exit the MS-DOS mode without doing a "DIR"...

Restoring Special Byte-Code

Warning! Do NOT go to MS-DOS mode under W95 and do a "DIR" command! This will nuke the special byte code created on the refdisk. To put the code back on, use Bob Eager's REFSTAMP.


With some refdisks/option/flash disks, I had trouble under Win NT 4. However, going to the MS-DOS prompt and typing "forcedos *.exe" the self extractor would work.

If you run the self-extractor from a path that contains at least one long file name, you will have this problem. You can also solve it by copying the self extracting program to a path with names equal to or shorter than 8 characters.

Refdisk Requires Cold Start

The correct procedure for using the Personal System/2 reference diskette is to power on the system with the diskette inserted in the diskette drive. Soft booting the reference diskette (ie. Ctrl-Alt-Del) may cause false errors as well as a false indication that a power-on password is already present when you try to set one.

Can the Wrong Refdisk Damage My PS/2?

Normally, no. For non-Flash based systems (50, 55SX, 56, 60, 65, 70, 73, 80 for example) the system has ADFs for the planar, and the POS circuitry identifies the specific features available to the systems programs. If you use the wrong refdisk, the system will tell you that you have been bad, and MUST be punished... (actually, it says the refdisk is not the correct one for the system, the system is now locked, and you must Ctrl-Alt-Del to get it to work again)

Note: For certain Flash-based systems, specifically the 9585 (X vs K / N models) and any system with an upgrade planar (50 thru 80), you CAN duff it up. Reply made upgrade planars under their name (and specific BIOS) AND under the IBM name (and specific BIOS). We are not sure if IBM played about with the POS registers with the re-branded Reply boards, but it sure looks like the ADF resources are different... YMMD

Warning: Making "cooked" reference diskettes to "add features" that are not officially supported by your system (even if the hardware supports it) may really mess things up and might cause your system to reject valid reference diskettes. For more, see the near disaster that resulted from hacking a refdisk on a P75...

Copying Option ADFs to the Refdisk CORRECTLY

Just copying the ADF to the refdisk will NOT always work. Before installing a new adapter, run Systems Programs (or Setup to non-IBM types), choose "Copy an Options Diskette" from the main menu, and stick in a floppy with the new ADF(s) (*.ADF, C*.ADF, I*.ADF, and *.DGS) on it when prompted. Now when you install the new adapter, the refdisk HAS the new ADF(s) on it, and it can autoconfigure without flashing that annoying "The description file for the adapter in Slot x was not found".

If you are installing an IBM option, you may need both the ADF -AND- *.DGS (IBM adapters have *.dgs files). Early systems use a single floppy for all setup and diagnostic files, while later systems use two floppies, one for setup files, the other for diagnostic files.

Note: Non-IBM adapters do not have a *.DGS file and will not show up under Advanced Diagnostics. You will need the stand-alone diagnostics from the adapter's manufacturer.

Note: If you are running an IBM adapter without a *.DGS, it will still work, just that you can't run diagnostics on it.

Functions and Relationship of COMMAND.COM and CMD.COM (from WBST)

Each RefDisk has its own, unique COMMAND.COM which:

Checks for correct system unit type (via Int 15h AH=C0h call and test of the returned values, primarily the Model-Submodel-Revision bytes, but possibly others for specific feature support).

Displays the announcement "splash" screen

Implements any delay -or- key-press processing before entering Main Menu display

Invokes CMD.COM when CTRL-A is pressed [Advanced Diagnostics].
   Note: CMD.COM must accept a parameter to distinguish between "Advanced" and "Test the Computer" invocations.

SC.EXE Trivia

>Time for wild speculation and downright baseless opinions. Which version of IBM PC Dos would work best with the 1990 vintage SC.EXE?

From Peter:
   The pre-1992 versions of the reference / diagnostic disks were mainly based on PC-DOS 4.0 (4.01) - which caused several problems with bigger harddisks. IBM replaced the versions with a PC-DOS 5 based system after complaints.

The SC.EXE however should not query the DOS version number, because the modified COMMAND.COM used on the reference disks does not return any DOS version number at all. So it will -most likely- run under any DOS version 4.0 and above. I -at least- had no problem booting up a Mod. 70 for example under PC DOS 7 - putting the refdisk in A: and type "SC" at the A:> prompt.

Run SC.EXE from HD?

From Rich Wolos
   Probably don't qualify for any titles, but we did put the refdisk files on several Model 70 hard drives at the shop. (in \refdisk directory).

Found we usually could run SC.EXE (set config) to add/remove memory, also adapter cards if the ADF's were there, and also setclock.exe and few others. Someone discovered you could type c:\refdisk>command and that would bring up the opening refdisk menu.

Common Refdisk Files



BACKUP.EXE Backs up reference and diagnostics disk, or does it back up the CMOS contents to floppy?


DIAGS COM The big enchilada that calls up the *.dgs files and runs diagnostics.

KP.COM Keyboard password utility (KP.COM) locks the keyboard temporarily without turning the system off.


PASSWORD.COM Power-On Password application?

POSTERR.COM Brings up a simple message in case of a POST error...

RECV35.COM (Thanks, David Beem!) A parallel port Interlink (before there was such a thing). IBM sold an option of a dongle that was attached to the DB25 PS/2 parallel port & had a Centronics 36-pin connection on the other side. The option included a diskette with the file for running on the other system with the printer cable to connect to the dongle. On the PS/2 you could map the others' drives to copy files (It was marketed as a way to transfer files from the older 5-1/4 format to the new 3.5 format used on the PS/2.). Look at the Data Migration Facility

SETCLOCK.COM Sets the date/time. Runs from command line.

SETRATE.COM Sets typematic rate for KB. Runs from command line.

SC.EXE The big enchilada for setting configuration. Will run and configure from command line in a pure DOS (MS or PC) environment.

UPDATE.EXE Updates BIOS in CMOS? Or does it update CMOS info on floppy?

USERINT EXE User Interface

DSPREVL.EXE "Display Release Level" (?) where it shows BIOS and ref/diags levels.

IBMCACHE.COM The installation program IBMCACHE.COM copies IBMCACHE.SYS
from the backup copy of the Reference Diskette to the root directory of fixed disk drive C, and creates or modifies the fixed disk CONFIG.SYS tile to contain a statement with this format:

device = \ibmcache.sys [sssss] [/E] [/Pn]

[sssss] is the cache size in K Bytes, and is specified as a decimal value. The valid range is 16 to 512 if low memory is used, 16 to 15360 if extended memory is used. The default cache size is 64KB for low memory, 128KB for extended memory.

[/E] tells IBMCACHE.SYS to use extended memory. The default condition is for IBMCACHE.SYS to use low memory.
Note: High-speed communications may overrun and create data Errors if the cache is in extended memory. Also, IBMCACHE.SYS is compatible with VDISKSYS, but may possibly conflict with other extended memory applications.

[/Pn] is the cache page size in sectors. Valid values for n are 2, 4, and 8. The default page size is 4. Some application programs may perform better with different page size values.

IBMCACHE.SYS IBMCACHE.SYS is a device driver that allows a portion of the computer memory to be used as a fixed disk cache (see the DOS manual for information about device drivers and the Buffers command). It can speed up application programs by keeping in the cache fixed disk data that is accessed repeatedly. When an application program requests fixed disk data that is already in the cache, the data is sent directly to the application program. This is quicker than if the data had to be read from the fixed disk again. Only one IBMCACHE.SYS device driver can be installed. It uses about 8KB of memory plus the size of the cache. All fixed disks attached to the computer are supported.

INSTALL.COM I think this is "User Install" where you can install utilities like KP.COM and PASSWORD.COM.

DASDDRVR.SYS Full description HERE.


DISK386.SYS Slight details HERE.



Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 08 May 2024 - Changelog | About | Legal & Contact