Internal Tape Backup Unit (ITBU)

EZDOS322 EZ-Tape V3.22 DOS Backup Software (Thanks to Niels C. Grønlund)
EZT_222 EZ-Tape V2.22 Backup Software (older; self unpacking archive)

188-148 IBM Personal System/2 Internal Tape Backup Unit
190-051 IBM PS/2 ITBU Installation Kit A 65SX and 8580
190-181 IBM PS/2 ITBU Installation Kit B 65SX, 80, 90 and 95
191-093 IBM PS/2 ITBU Installation Kit C 8540, 8565, 8580, 8590 and 8595
193-126 IBM ITBU Installation Kit D Note: Allows PS/2 ITBU drive to be used in:
   VP 6382, 6384, 6387, PS/1 2155, EduQuest 9603, 9604, 9605

itbudiag.exe Internal Tape (ITBU) diags ver 2.0
itbuopt.exe ITBU Opt/Diag & Adapter Diskettes
Looks like the diagnostics are from PS2TAPE from Irwin Magnetic Systems Inc.

Making floppy drive adapter (by Bob Eager)

ITBU Frame
   J8 Pinout
ITBU Installation Kits for PS/2s
ITBU in 95XX Systems
Using ITBU on Later Systems 
AIX Drivers
/etc/backup Inefficiency
ADF Sections

ITBU Main PCB 4302005

C46 2200uF 16V
IC14 Irwin Magnetics 6000034-A
IC15 Zilog Z086112VSC Romless
J1 Vertical riser header 28 pin
J2 Tape drive motor
J3 Drive activity LED
J4 Head positioning stepper
J5 Tape selection switches
J6 Unused drive activity LED?
J7 Tape head
J8 Drive selection
Q8,10,12 IFR9010
Q7,9,11 IFR010
X1 800M9A xtal

ITBU Frame

Sort of a crude design. The read/write head is mounted on a pivoting arm driven by the stepper motor at the rear. Think of a see-saw. The head moves up and down on two vertical shafts.

Note the two switches at the upper right. I believe that they are for write enable and tape capacity.

J8 Pinout

Look at the rear of the drive with the edgecard on the right.

> What is the purpose of the 10 pin header J8 to the immediate left of the edgecard? It has a two wire jumper on the second pin pair from the edgecard.

Rick Ekblaw reaches way up and snags it with:
   Clearly, it's mostly used for tape drive selection.  You'll note that pins 1, 3, 5 and 7 are all tied together (and presumably go to the tape drive SELECT logic), pin 2 connects to the card edge pin 10 (-Motor Enable 0), pin 4 to card edge pin 12 (-Drive Select 1), pin 6 to card edge pin 14 (-Drive Select 0), pin 8 to card edge pin 6 (Reserved), pin 10 to card edge pin 34 (-Ready).  Pin 9 connects to a via on the drive PCB, I didn't bother to trace it out.

You might wonder why card edge pins 10 and 6 would be used for drive selection, since they are not listed as drive selects.  I suspect that the manufacturer of the IBM ITBU (Irwin) used the drive selection pinout of the Sony 34-pin floppy interface (where pins 10, 12, 14 and 6 correspond with drive selects 0, 1, 2 and 3), and since the ITBU was only intended to work with drive select 1, nobody paid attention to the other pins.  The ITBU is similar in design to the Irwin Accutrak A250, but they are not the same drive (the A250 is used in IBM PC/AT compatible designs, the ITBU is designed to work with IBM PS/2 logic levels).  The ITBU is supported by the Irwin EZ-TAPE software.

Internal Tape Backup Unit Installation Kits for PS/2s

The IBM PS/2 Internal Tape Backup Unit is an internally mounted product that performs fixed disk backup and restore for the following IBM PS/2 products.

30F5279 Installation Kit A 65SX, 8580
64F7465 Installation Kit B 65SX, 80, 90 and 95
87F9826 Installation Kit C 8540, 8565, 8580, 8590 and 8595

Not sure of this snippet from the EPRM:
8525, 30, 50, 55, 60, 65, 70, 80, 9556, 57, 76, 77

IBM PS/2 Internal Tape Installed in 95XX (H12308)

Customers that have installed a IBM Internal tape drive in the following machines

**PS/2's that have a third berg connector on floppy cable

And are having trouble using their tape drive. Check to see if the tape drive is connected to the third berg connector (usually the nearest connector to the motherboard).  This cable will usually have a mark on the connector with the following labels:


The tape drive generally will be connected to the second berg, but to be correct it should be installed in the 3rd connector and the 3rd drive bay of these boxes 9577, 9557.
   Installation documentation does not point this out.  It makes more sense to logically connect tape drive to third connector because a second floppy could connect in 2nd berg.

**PS/2's that have 3 berg connectors on them could also be 8590 and 8595.

Note:  In the case of machines running 4680 OS, the 2nd connector of the cable should be used. Keep in mind that DIAGNOSTICS MAY FAIL WHEN THE TAPE DRIVE IS ATTACHED TO THE 2ND DROP.

ITBU Use on Later Systems

>I have never been able to get the PS2-Tape working on 9595 type 4 complex. No problems on an 8595 or a SCSI MB 77. 

Peter utters:
Yep. They added "security stuff" to the FDD interface in the 9595-series and I guess that louses up the interface a bit and causes incompatibility with the old floppy streamer. I had one of those Irwin derivatives running in an 8595-AKD in the company back in '92 or so. Never got it to work in later machines.

The unit allows the user to transfer up to 80MB or 120MB of data from a fixed disk to a removable tape cartridge. The tape drive slides into the Diskette Drive B slot in the PS/2. 

The ITBU uses a 3.5" mini tape cartridge. The following cartridges are supported:
DC2080 formatted Rhomat 80MB
DC2120 formatted Rhomat 120MB

Any media that meet the specification in the Proposed ANSI Standard X335/87-218 "Unrecorded  Magnetic Tape Mini-cartridge"  for Information Exchange. 

The tape unit requires the IBM PS/2 ITBU Backup program for operation. This program is not provided with this option. (PCTOOLS V-7.x and other Utilities) 

Accelerator Cards  Irwin 4100MC 1-Mbit (MCA)  ADF Sections for 4100MC


  • Supports Models 50, 60, 70, and 80
  • Up to 80Mb storage capacity
  • Supports data interchange between PS/2 Models 50, 60, 70, or 80
  • Internal unit 3.25" form factor
  • Slides into existing diskette controller (Drive B position)
  • Accurate head positioning using closed-loop embedded servo
  • Uses 1/4" tape mini-cartridges
  • Backup rate approximately 2Mb/minute.

        The use of extended length mini-tape cartridges with the PS/2 Internal Tape Backup Program and the PS/2 Internal Tape Backup Unit will allow users to store and retrieve up to 120Mb of data on one minicartridge. Ed. When did this happen? 

Installing the Tape Unit 
   Install the Tape Unit in an empty Slot or Tray. Connect the B-diskette drive cable to the ITBU connector. Install the model-required tape cover plate. On the backup copy of the Reference Diskette, install the Diagnose and @ADF-file with the COPY an OPTION diskette function. 

Cleaning the Tape Unit Read/Write Head 
   It is recommended that periodically the ITBU read/write head should be cleaned. The head must be cleaned if there are read or write / format errors or a large number of bad blocks. This should be done by using a cleaner cartridge.

ITBU AIX Drivers

>Can aix 1.2 talk to the internal tape unit?  That's the one that sits in the second drive bay on a model 70. If so, what device does it respond to?

Harry Haas:
   It seems that IBM must have forgotten this drive when they put together AIX. After much searching I found that I had to file an RPQ (?) with IBM. For me, all this meant was calling my IBM rep and giving her this number: Model DGL, RPQ# P91038, and agree to pay $17.50 when the disk arrives. What I got was the "IBM AIX/PS/2 Internal Tape Device Driver 5799-DGL"
Now this was back when I was running Ver. 1.1, so 1.2 MAY have the driver built in. I believe you would find it under: /usr/lpp/itbu

The driver works fairly well, but you cannot mount the drive, only backup and restore to/from it. Also the documentation on the RPQ is vertually non-existant. You have to read through the file:
/usr/lpp/itbu/doc/ (the manual page that comes with it.)

Jerry Queirolo:
   I ordered an IRWIN Accutrack A250 to make the transition as easy as possible. The A250
*is* an ITBU, just with rails and faceplates for clone chassis, not PS/2's.

PS/2 ITBU and '/etc/backup' inefficiency (from Don Reif)

Still wondering why '/etc/backup' can't dump more than 40 MB to an 80 MB (DC2080) or 120 MB (DC2120) tape cartridge in an ITBU?  If so, then read on.

It turns out that the 'backup' program (when invoked with -f/dev/rst0) defaults to a tape density (d) of 700 bytes per inch and a tape length(s) of 4500 feet.  That works out to a limit of 36,000 1K blocks per tape cartridge.  In other words, 'backup' does not automatically determine the type of cartridge installed and write an amount of data appropriate to the installed cartridge.

The documentation tells us we CAN'T change the density parameter or the tape length parameter when used with the ITBU. This morning I tried playing around with the -d and -s parameters and I can now say that the documentation is wrong.  It is possible to tweak these values and have 'backup' use much more of the tape cartridges.

There are several known facts:

The ITBU hardware uses 32 data tracks.

A DC2080 tape is 205.0 feet long, therefore use -s 6560.
A DC2120 tape is 307.5 feet long, therefore use -s 9840.

A little on the conservative side, I want 'backup' to use only 75 MB of a DC2080 tape and 115 MB of a DC2120 tape (to allow for bad blocks which should be formatted out).  So ...

Total Capacity = tape density * tape length * 12

tape density = Total Capacity / (tape length * 12)
   = 75 MB / (6560 * 12)
   = approximately 1000 bytes per inch

The tape density is the same for both DC2080 and DC2120 tapes, the increased capacity is due only to the increased tape length.

For DC2080 tapes:

find . -print ! /etc/backup -s 6560 -d 1000 -i -v -f/dev/rst0

For DC2120 tapes:

find . -print ! /etc/backup -s 9840 -d 1000 -i -v -f/dev/rst0

From Tim Clarke:
   Originally, IBM PS/2 Internal Tape Backup Program (DOS) which was effectively Irwin EZ-TAPE. This latter was still locatable via:
Central Point CP Backup (included in PC Tools v6.x+ and PC-DOS v6.1+) is a nice friendly DOS/Win3.x package that supports it. Also, IBM's later DualStor Backup Program (DOS/Windows and OS/2 versions), if you can find a copy. There are W95 fixes for the DOS/Windows version still around on the IBM PC Co. BBS FTP site.

> Is there a utility for formatting rhomat tapes of 120 meg?  I have formatted many of the 80 meg but my utility doesn't include 120 meg and they show only 80 meg when using that utility. 

Bob Eager says:
   You need to realize (if you don't that is) that there are TWO different lengths of tape you can get. One is the 205 foot version, and the other is 307.5 feet. The numbers are somewhat confusing and depend on whether pre-formatted, but DC2000 is usually the 205' one, so is DC2080 (80, you see). DC2120 is the 307.5' version and is not usually formatted (confusing!).
   If you have a 205' tape you CANNOT format it to a greater density. The Rhomat format is already packing more onto the tape than most formats do.  Of course, compressed you may be able to double the capacity but that is not a formatting issue.

> The 2120 will work; so will the 2080. However, it needs to be the Rhomat format with special servo tracks. Either get Rhomat format tapes, or get  truly blank tapes and format them (takes 2-3 hours).

Just to expound on that last point a bit:  When Bob says "truly blank", he means it.  I had received a small herd (30 to 40) of DC2120 Ximat tapes that I wanted to reformat and use in the ITBU.  Since I have a Taberaser 409 available to me at work (a 40-plus pound monster of a tape degausser, intended to work with reel tapes, including the old wide reel-to-reel video tapes), I figured that erasing the DC2120 tapes would be easy.  Each one I tried would start running the format procedure, and fail after an hour or so.  Then I got the word that they had to be *really* erased to reformat to Rhomat.  So I took the tapes back to the Taberaser, placed them metal side up, and hit each one with 4 erase cycles.  Every single tape then formatted properly (running PMTAPE under OS/2, of course, but I would expect that the DOS version of the ITBU tape program would work as well).

Rick Ekblaw

@707E.ADF Irwin 4100MC Controller

I/O Addresses
      <"10F0h-10F7h"  io 10f0h-10f7h>, 12F0h-12F7h, 14F0h-14F7h, 18F0h-18F7h, 20F0h-20F7h, 28F0h-28F7h, 30F0h-30F7h

Interrupt Request Level
       <"5">, 6 (share with Diskette), 10, 11

Arbitration Level
    DMA channel the adapter will use to transfer data.
     <"1">, 2 (share with Diskette), 3, 4, 5, 6, 7

Fairness On/Off
   Fairness controls whether the adapter will release control of the bus to another device when it has been using it exclusively.
          <"On">, Off

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