News from the Rolm Front (Feb. 20th 2012)

Together with a companion we visited 'PVA' company near Frankfurt. Acquired lots of technical documentation and a Miltope 8" floppy disc drive.

Here are some closeups

10 kg and the width of a beer bottle / floppy centering mechanism / read/write head and downholder / Front panel

The floppy is designed to withstand shock loads of 15G

This video clip is an IPL (initial program load). It positions the read/write head to tracl 0 (out of 77 total tracks). Track 0 usually holds the boot sector.


News from the Rolm Front (Sept. 29th 2011)

Together with a companion we auctioned a few (10 ones altogether) Rolms 1602, Military designation AN/UYK-19 yesterday for almost nothing. However I had to drive almost 900km to Munich and back. The Toyota Landcruiser could barely hold the masses of equipment. I had to leave behind a nice DEC PDP-11/34. It was just too large and -very- heavy. We two guys almost couldn't lift the frame up. So it had to stay together with all the RL-02 disc drives and masses of other nice gadgets from the past.

The guy selling the Rolms has inherited a warehouse full of antique electronics and computer equipment - unbelievable

some extension cabinets not shown here


This time my prey was much more complete than my first Rolm acquisition. I got two control panels (the nicest piece of a Rolm). A 110-to-220 V power converter for each Rolm. Two rare HUGE floppy disc drives. Two large boxes with cables of all sorts. Extension chassises(?) aplenty. And a large box of extra power supplies. - What a treasure.

Next I will report when the red LEDs on the control panel will light up again.


Current Inventory

 my number  Rolm/ MILTOPE Designation  Description  Options/Comments  No. of items  Comment
 1  1620B  Processor  34, 60  1

Si F1 bis F4 kontrol., OK. Bei J10 110V eingespeist, PwrOn/Reset - keine Reaktion, Netzteil gewechselt - das gleiche :-(

Keine Spannung gem TM-11-7021-201-30 Seite 2-10

 4  1602B  Processor  2, 8J, 11, 15, 21, 35, 60  1  gleiches wie bei 1
 5  1602B  Processor  2, 15, 60  1  gleiches wie bei 1
 11  1602  Processor  6, 2, 10, 21, 30, NO front end, no Pwr.Supply  1  
 15  1602  Processor  2, 7, 10, 21, 30, NO front end, no Pwr.Supply  1  
 6  1626  I/O Processor  2, 11, (X6), 21, 35  1  
 8  1626  I/O Processor  2, 8J, 11(X4), 15, 21, 35, 11  1  
 16  2149  I/O Chassis  2, 10, 30, S045  1  
 10  2150  Interface Chassis  2, 21, 60  1  
 13  2149  I/O Chassis  2, 30, S045, Special  1  
 14  2149  I/O Chassis  2, 11, 14, 20, 30  1  
 7  2141  Memory Chassis  -  1  
 17  2142  Memory Chassis  'Configuration B'  1  
 17  2142  Memory Chassis  empty  1  
 9  2145  Memory Chassis, 64K  -  1  
 3  1635  Control Panel  18, 81(?)  1  
 12  'Special'  Control Panel  -  1  
 18  S001  Control Panel  10, 29, Special, NO Keys!  1  
 18  5605  WCS Micro Control Panel  Model S487  1  
 -  S002  Power Adaptor  with 110V AC socket  2  
 -  S003  Power Adaptor  NO 110V AC socket  3  
 -  'Special'  Power Adaptor  with 110V AC socket  2  
 -  DD400MX 45008  Floppy Disk Drive   28VDC  2  
 -  5686  Power Supply  option 2, for 1602 Processor  2  6 times 1602, only two power supplies :-(
 -  unidentified  Power Supply    2  no label found
 -  5616  Power Supply    3  one labelled 'spor. defect'
 -  5614A  Power Supply    3  



My Rolm 1666B mil-spec Computer

military designation: AN/UYK-64(V)




How it all began
Buying an antique computer
Box arrived
First inspection
Disassembly and repair
Lights On!
How old?
PCB Inventory
Next activities
Right or wrong?
Related Links


How it all began,

...sometime in the late 70's, early 80's. I was a young computer engineer working in a small company doing fascinating programming jobs. There were no PCs and no Microsoft Windows at that time (what a relief...). The equipment being used at that time were either mainframes (IBM 360s and similar heavy iron) or 'Minicomputers'. Don't take 'Mini' in the sense of today's PDAs or alike. The typical minis were Digital Equipment's PDP-11 and Data General's Nova/Eclipse. A well-equipped Nova 3 could easily fill two or three cabinats and weigh 100 kilograms or more. At the beginning, software was punched on card-stacks or papertape.

Diskettes were 8 inches and stored a whoppy 160 kilobyts. The larger harddisk-drives were about the size of laundry machines with capacities of around 10 megabytes.

This was the time I fell in love with the Nova's elegant and very clever instruction set. Four general-purpose 16-bit registers, a genial indirect adressing mode-bit and an adress-space of 32K (77777 octal) words. The instruction set was so intuitive that it easily could be memorized (in Octal-code). Should there be no terminal around, instructions could be entered via the 16 data and address toggel-swiches on the Nova's frontpanel. Everything you need for degugging was a Start/Stop, Display/Deposit and Single-Step switch. The military/ruggedized variant of the Nova was the Rolm 1602. An almost indestructible aluminum piece of engineering artwork. The most advanced Rolm was the 1666B, an equivalent to Data General's line of 'Eclipse' superminicomputers. At that time I wouldn't imagine that I ever would own such a treasure (which, besides, went over the counter for $218,000 per piece at that time).



Buying an antique computer,

...when you grow older more and more often you get such sentimental moments... Recently I was surfing the web for reminiscences to the good 'ol computer times. I sympathized to buy some antique computer equipment (people buy Louis-Quatorze chairs for a lot of money and nobody will smile about that...). My favourites were either some original Altair/IMSAI or a real DG Nova. However both of these are very rare and people who own an IMSAI dont'want to give it away anymore. So one Sunday night in my basement hobby-room I discovered this ebay entry:

THIS was the one I was waiting for! I had to have that one. Unfortuntely the guy (yes he's name is 'Guy') who sold the Rolm lived halfway 'round the globe (Sydney, Australia). Surprisingly the airfreight rate was reasonable. I did know the forwarder (BAX Global, both thumbs up) from a previous shipping and so I put an initial bid on the Rolm. Because noone else increased the bit, I won. Money was transferred via PayPal (which took almost a week until it arrived at Guy's account. Meanwhile Guy screwed and glued a plywood box together. The transport was uneventful. Even my concerns about customs was unfounded.



Box arrived, Power and Documentation needed!

A week later I picked up the 60-Kg box at Frankfurt cargo center. What I still needed now was a 240-to-115V transformer. I ordered a 1000W one, factory-new on ebay for just Euro 60. Now there was one last hurdle to take. I got a couple of cables with the Rolm but no power cable. The question now was how the power is wired to the 7-pin socket (J1). The owner of PWA Electronic was very helpful and mailed the pinouts immediately. After some Google searching I found This people sell a lot of outdated military literature. And voila- I found the complete maintenance and repair handbooks. For a few $ I odered the CD which arrived a few days later.



First inspection

This was my second Christmas and of course I had to have a look inside the black box ;-) However I did not follow my temtation to just hook up the power cord. From collectors of antique radios I learned that the electrolytic capacitors will leak and dry out after so many years. If such an electronic circuit is powered up then it will smoke up immediately or even explode. So, one of my first looks went to the power supply. By loosening eight self-retaining screws the power supply can be taken out in a few seconds


Rear (*1) side of power supply (and Rolm) with blower and diffusor to both sides of the box


Sidenote: *1: actually by manufacturer/military terminology this is the front side. But this end really looks more like a vacuum-cleaner than a computer. So I will use front and rear in a reverse sense.


Not a single wire has to be removed if the power supply is pulled out. The contact fingers of the mainframe easily slide into the sockets of the power module. Lots of amps are flowing thru this massive bus bar (lower front). Regard the two guide pins located right and left above the socket. Proper alignment always is assured even if the power supply is inserted in a hurry (because of friendly fire maybe ? ;-))



Disassembly and repair

This capacitor (220uF, 50V) was the only component which was obviously defective. When I removed the transparent coating a smell like old fish escaped. I exchanged it by a new, smaller one of same capacity, voltage and temperature range (mil-spec parts are good for up to 105 °C).


Frontside with all sockets (*1) If all plugs are installed, it is not easy to remove them again, because they are so close together that one hardly can turn the bayonet shells with fingers. For the purpose of installation and removel we used to use special pliars at that time. The 'S' in 1666B-S indicates this is a later semiconductor memory model (the earlier models were of core memory).


*1: the sockets alone cost more than a current personal computer


Inside of the box. All boards are installed, power supply (right) is removed. All boards are multilayer (yes, multilayer was a known but expensive technology in 1984) and covered by an aluminum plate. The chips are thermically bonded to this aluminum plate which distributes the heat to both sides. Using Allen-screw-operated wedges, the board-sandwiches are tightly clamped to the grooves on the sidewalls. This way the waste heat is transferred throught the sidewalls and removed by the right and left heat exchangers which are fed by the blower on the rear end. This construction assures a hermetically sealed confinement. No dust or humidity can enter the internals of the computer. There even was a special tool for board removal.


Backplane with wiring. Note the many wires on the forward boards. I assume this could be the connections to several multiple serial I/O interface bords. Probably a computer used for data communiction. I have to investivate deeper in this.



Lights On!

Changing all the remaining capacitors just for safety reasons is not feasible. So I slipped the power supply in and... time has come!

Big surprise - All lights are on, fan is running (my hands shaking for excitement). Reset and BITE do respond when depressed. So... is this machine really computing now? - I cannot tell at the moment, but it looks not bad.



How old is this Guy?

No, not me, I mean the Rolm...

This is Rolm is of serial number 618. The PCBs of the power supply carry 1981 as date of manufacture. The warranty seals on the case shows '25th Nov 1986'. So it's 20 years since the case was open the last time. The front side of the Rolm carries an 'ETM' (operation time logger). That one shows 690 hours of operation. This confirms with the overall good condition. The mechanical components show only very little wear (and no bullet holes at all).



PCB Inventory

This is the inventory of printed circuit boards of my Rolm. The card cage has a total of 22 slots. Between slot 11 and 12 there is an solid aluminum divider separating the card cage into two departments. All slots except slots 13 to 15 and 19 to 22 are occupied.

 Slot #
 Module name, Description, Options  Model #  Serial #  QC Seal Date

 Priority/Load Module A  3566  11090  18.Dec. 85

 Adaptor, Fixed Disc  4055  384  17.Dec. 85

 Floppy Disc Interface  3382  953  2.Juni 85


 Async Line Multiplexer

Options 8(4), 9(75,300,1200,2400), 90(x4)

 S617  193  18. Dec. 85


 Async Line Multiplexer

Options 8(3), 9(75,300,1200,2400), 90(x4)

 S617  219  18. Dec. 85


 Async Line Multiplexer

Options 8(2), 9(75,300,1200,2400), 90(x4)

 S617  138  5. Sept. 85


 Async Line Multiplexer

Options 8(1), 9(75,300,1200,2400), 90(x4)

 S617  201  18. Dec. 85


  Async Line Multiplexer

Options 9(75,300,1200,2400), 90(x4)

 S617  229  18. Dec. 85


 Processor Card Set,


 5711  807  18. Dec. 85


 Processor Card Set,


 5711  585  18. Dec. 85


 Processor Card Set,

CPU Data, Options 45 (2400)

 5711  809  18. Dec. 85


 Processor Card Set


 5711  919  18. Dec. 85




 ERCC Controller  1754  507  18. Dec. 85

 High Density Memory Control  1753A  370  12. Dec. 85

 Semiconductor Memory Module 512K (*1)  2032  287  15. Aug. 85






*1: of course kiloBITS, makes a whoppy 65 kilobyte of main memory


Next activities

Next activities will be to find out if the processor is really working. Because this type ofcomputers don't have an external operating panel with lights and toggle-switches, the only way to get access to the CPU is via the system console (virtual control panel). A PC running HyperTerminal will make a good candidate for a system console. The Boot ROM of the Rolm also contains a kind of interpreter which allows to modify memory locations and accumulator contents. It could even be possible that there are hardware tests implemented - but this at a later date.



Right or Wrong?

(1) Real computers don't need a Reset/Reboot-button (only Windows PC's do)


Wrong! the Rolm got Three(!) of them. A 'Power-On Reset', a 'Run Reset' and a 'BITE/Boot' button.


(2) Real computers don't crash (only Windows PC's do)


Wrong! Proof: aim with a calibre .50 BMP weapon on the Rolm and you can watch the crash ;-))

Sidenote: destruction of army electronics material to prevent enemy use shall be accomplished in accordance with TM 750-244-2.



Related Links

this company still sevices Data General and Rolm computers

this company offers emulation software to run DG and Rolm native programs on modern equipment, even personal computers

besides other business activities also this German company services Rolm equipment. The owner of this company was very supportive when I asked for a pin-layout of the Rolm's power

connector. Thanks for this




If the kind reader of this lines is also interested in historic Rolm and DG computers, please don't hesitate to contact me at:

ga at loeff dot de


Or if you even could tell me where I could get (preferrably as an inexpensive surplus item) this 7-pin power plug, then you'd save my day ;-)

This is a treaded socket (threads on the outside). I could decipher 'SAE 18-9' - maybe the thread designation. The outside diameter is about 28.5mm. The upper five pins are about 1.2mm in diameter. The two larger pins below are about 2.4mm in diameter


Got one for free from PWA Electronics, Thanks, guys.