how fast were drum memories?

[Mike Loewen]

    The manual says 125A per phase (3-phase, 208V) starting current.

    I remember spin-down as 20 minutes, but that was a long time ago.  :-)

On Fri, 11 May 2018, Paul Anderson wrote:

> The good old days...
>
> I recall the Q-7 drums would take about 15 minutes to come to a stop when
> turned off, and would power up in seven seconds or less. Surge current was
> around 115 amps?
>
> Paul
>
> On Thu, May 10, 2018 at 3:46 PM, Mike Loewen via cctalk <
> cctalk at classiccmp.org> wrote:
>
>> On Thu, 10 May 2018, Al Kossow via cctalk wrote:
>>
>> On 5/10/18 10:37 AM, Al Kossow via cctalk wrote:
>>>
>>>>
>>>>
>>>> On 5/10/18 9:29 AM, Paul Koning via cctalk wrote:
>>>>
>>>> One that comes to mind is the DEC RS04.  It spins at roughly 3600 rpm (a
>>>>> hair less, so obviously a 2 pole induction motor running off 3-phase 60 Hz
>>>>> power).
>>>>>
>>>> Vermont Research drums (model 1175B) spun at 3450 rpm 3ph 220v, The HP
>>>> 2773 on the 2000A TSB was from VR so I expect RPM
>>>> would be similar for most drums of similar diameter.
>>>>
>>>
>>> Just checked, and the LGP-30 and RPC-4000 drums are both listed as 3600
>>> rpm
>>>
>>
>>    The drums on the SAGE system (12 on each side), are listed as follows:
>>
>> Diameter:       10.7"
>> Width:          12.5"
>> Weight:         105 lbs (cylinder, only), 450 lbs for entire drum assembly
>> Speed:          2914 rpm
>> Heads:          Up to 12 R/W bars, with up to 40 heads on each bar, 1
>> erase bar
>>                 6 pairs, one for Compuuter-to-Drum (CD), one for
>>                 Other-than-computer-to-Drum (OD)
>>                 Head spacing 0.3" apart on each bar
>> Drum Layout:    2048 registers on 33 channels (tracks), 6 fields
>>                 Channel spacing is 0.050"
>> Access Time:    Maximum 20ms, average 10ms
>> Write Current:  110ma
>>
>>    The R/W bars are arranged in pairs (CD and OD) so that I/O devices can
>> access the drum independently of the computer.
>>
>>    More than you ever wanted to know about SAGE drums (thanks, Al!):
>>
>> http://bitsavers.org/pdf/ibm/sage/3-42-0_Drum_System_Sep58.pdf
>>
>>    Here's one of the earlier style R/W heads:
>>
>> http://q7.neurotica.com/Oldtech/SAGE/DrumHead-1L.jpg
>>
>>
>> Mike Loewen                             mloewen at cpumagic.scol.pa.us
>> Old Technology                          http://q7.neurotica.com/Oldtech/
>>
>

Mike Loewen				mloewen at cpumagic.scol.pa.us
Old Technology				http://q7.neurotica.com/Oldtech/