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old tape drives.

RobS

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I would love a vacuum column type drives of any vintage or condition to use with a pdp8 straight 8
'Hachti' in Germany got himself a Honeywell tape drive to use with his Series 16 computer. His experiences are documented here: http://h316.org/stuff/tape_drive/ Even though his kit is all Honeywell the tape drive native electronics is Series 200 technology and involves an interface with uPac technology to work with the Series 16 - and apparently that was Honeywell's official way of doing things. I know a former Series 16 engineer who had to work on the interfaces between the two technologies at Honeywell and apparently they had different signals, timings, protocols, pretty much everything. Honeywell did tend to acquire technology from other companies rather than sticking to their own brand, which is why I'm trying to keep to just their own original technology in my Series 200 project. Hachti has to contend with getting the Series 200 logic to work as well as the Series 16 and on top of that he has failures in the vacuum system because old rubber diaphragms are leaking. Some months ago I sent him some replacement vacuum sensors from my collection to fix the leaks, but he's probably still got a lot of work to do to get the thing working and it is really well-made really heavy equipment. Therefore I agree that looking for any drive of any vintage in any condition may be unwise.

Personally I do have some parts from Honeywell tape drives but wouldn't want a complete drive. I still have tape reel motors with hubs, a pressure/vacuum pump and some solenoid valves with the electronics to operate them, but I'm hoping that I can eventually use them another way in my Honeywell 200 project. If we ever finish building the machine I'd like to equip it to whistle Land of Hope and Glory while drinking a glass of water to give it a bit of British flair even though that capability wasn't in the original American specification. I think that would be a better conversation piece than a tape drive. There have been suggestions that our respective replica projects are mad but there's a subtle difference between being mad and being British. Maybe one day I'll find out what it is.
 

Chuck(G)

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Even if you did you would instantly discover that IBM's drives are completely incompatible with DEC's systems.

Indeed; that held for most mainframe manufacturers. Building your own controller to comply with the original interface standards could turn out to be a huge project. And not all tape drives included formatters, so there's yet another level to figure out. Then there's the matter of power supplies.

Suppose you came across an old CDC 600-series drive, say, a 606 or 607. It's heavy--800 lbs. or so. It requires 3-phase 208V 60Hz AC (although I believe that there's a European option). Logic levels are -16 and 0 volts; special connectors. No formatter. Then there's the matter of getting unobtainium components for maintenance and repair.

It'd be great as a museum exhibit. Although the drive was wonderful in its heyday, I'd hate to try and get one to interface to anything made in the last 25 years.
 
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RobS

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Kent, England
Suppose you came across an old CDC 600-series drive, say, a 606 or 607. It's heavy--800 lbs. or so. It requires 3-phase 208V 60Hz AC (although I believe that there's a European option).

I have no doubt that interfacing the logic would be a headache but the power requirements could probably be met by a modern static phase converter providing 3-phase power at whatever voltage and frequency is required from a domestic single phase supply. Such devices are available at ratings from 1 to 10 kilowatts to operate industrial machine shop equipment in a domestic setting, provided that one is prepared to treat a tape drive as an item of engineering equipment rather than a household computer peripheral. That thought reminds me of this picture, which purports to show my favourite machine in a domestic setting: http://www.flickr.com/photos/mindspigot/2470218177/in/pool-60655796@N00/ I can't see my wife being so happy with that setup.
 

RobS

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That thought reminds me of this picture, which purports to show my favourite machine in a domestic setting: http://www.flickr.com/photos/mindspigot/2470218177/in/pool-60655796@N00/ I can't see my wife being so happy with that setup.

It just occurred to me that the setup in that spoof picture was quite plausible. The lower tape drive on the right of the picture was a Keytape machine, which was used to encode input from the keyboard onto mag tape to be transferred to the full height drive next to it to feed into the computer on the left. The project that I'm now working on involves using the logic boards from seven of those Keytape machines along with some other boards to build the computer CPU shown. While my mother-in-law tolerated my storing the logic boards in her garden shed for almost forty years I doubt that I could have got away with storing seven complete Keytape machines there. My wife isn't convinced about having just the CPU sitting in the house once it's built either. No, tape drives really aren't suitable as domestic pets.
 

rorypoole

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I have no doubt that interfacing the logic would be a headache but the power requirements could probably be met by a modern static phase converter providing 3-phase power at whatever voltage and frequency is required from a domestic single phase supply. Such devices are available at ratings from 1 to 10 kilowatts to operate industrial machine shop equipment in a domestic setting, provided that one is prepared to treat a tape drive as an item of engineering equipment rather than a household computer peripheral. That thought reminds me of this picture, which purports to show my favourite machine in a domestic setting: http://www.flickr.com/photos/mindspigot/2470218177/in/pool-60655796@N00/ I can't see my wife being so happy with that setup.

I think the smoke, crumbs and sticky fingers would not do the Honeywell 200 much good! I would find it much easier to sort the power supply problems than the logic interface
 

Chuck(G)

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I have no doubt that interfacing the logic would be a headache but the power requirements could probably be met by a modern static phase converter providing 3-phase power at whatever voltage and frequency is required from a domestic single phase supply. Such devices are available at ratings from 1 to 10 kilowatts to operate industrial machine shop equipment in a domestic setting, provided that one is prepared to treat a tape drive as an item of engineering equipment rather than a household computer peripheral. That thought reminds me of this picture, which purports to show my favourite machine in a domestic setting: http://www.flickr.com/photos/mindspigot/2470218177/in/pool-60655796@N00/ I can't see my wife being so happy with that setup.

Yup, pretty much a 3-phase motor with one leg capacitively coupled to the line. I've set a couple up for friends with old lathes. It works okay, but real 3-phase distribution is better. At least the tape drives didn't require the 3-phase 400Hz AC that the mainframes did. Those were always MG sets--I don't know where you'd find one now.
 

RobS

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Messages
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Kent, England
Yup, pretty much a 3-phase motor with one leg capacitively coupled to the line. I've set a couple up for friends with old lathes. It works okay, but real 3-phase distribution is better. At least the tape drives didn't require the 3-phase 400Hz AC that the mainframes did. Those were always MG sets--I don't know where you'd find one now.

I was actually thinking of a full digital phase converter, some of which do AC-DC-AC conversion, the solid state equivalent of an MG set in effect. On machine tools this allows the motor speed to be varied by varying the frequency of the supply rather than the voltage. I think that kind of device can actually provide 400Hz 3-phase power if necessary and it's quieter than an MG set.

The Honeywell 200 installation used at our company in the 1960s had an MG unit in the loft above the computer room to provide the 60Hz supply from our British 50Hz mains. Our office was above shops, so all the heavy stuff that would normally be in a basement was in the roof space and the computer room ceiling had to be reinforced to take the weight of the MG unit. Eventually the roof space became so full with equipment, document and paper stock storage and so on that the architects advised that the whole building could collapse, so departments like computer operations and printing services had to move out. It hadn't helped that the trend towards open plan offices had resulted in many of the internal walls being removed over the years as well. The company has almost ceased to exist now but the building is still standing. Solid state solutions don't make life so complicated.
 

Chuck(G)

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I was actually thinking of a full digital phase converter, some of which do AC-DC-AC conversion, the solid state equivalent of an MG set in effect. On machine tools this allows the motor speed to be varied by varying the frequency of the supply rather than the voltage. I think that kind of device can actually provide 400Hz 3-phase power if necessary and it's quieter than an MG set.

I think a VFD drive while probably very useful, is probably overkill. One benefit of a traditional MG set is the ability to "coast" over minor service interruptions, however. I recall that the 400Hz power supplies used in the CDC mainframes were scarcely more than transformers, a 3-phase Variac to adjust the voltage and a full-wave "star" rectifier setup. Brutal and simple--that's probably why they were used.
 
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