Difference between revisions of "RA81 Disk Drive"

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(New page: it's a dec disk drive. for a wealth of information... http://www.pdp-11.nl/peripherals/disk/ra81-info.html The RA81 is a random-access, moving head (Winchester) fixed disk drive and wa...)
 
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it's a dec disk drive.  for a wealth of information...
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[[Image:ra81.jpg|thumb|right|px200|4 RA81's in two cabinets]]
  
http://www.pdp-11.nl/peripherals/disk/ra81-info.html
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The '''RA81''' is a [[Digital Equipment Corporation|DEC]] [[disk|disk drive]], introduced in 1982. It is a moving [[head]] ([[Standard Disk Interconnect|SDI]] [[Winchester disk|Winchester]]) fixed disk drive. It has a non-removable media using a head/disk assembly (HDA) with a capacity of 456 Mbytes.
  
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The RA81 connects to the [[device controller|controller]] via the [[Standard Disk Interconnect]] (SDI) bus. Additional drives can be connected to a controller to increase the data storage capacity. The RA81 can also be connected in a dual-[[hardware port|port]] arrangement permitting time-shared access by two controllers.
  
The RA81 is a random-access, moving head (Winchester) fixed disk drive and was introduced in 1982.
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The RA81 is a self-contained disk drive with built-in cooling system and [[direct current|DC]] [[power supply]]. An RA81 disk drive subsystem is made up of an SDI disk controller and one or more disk drives.
It has a non-removable media using a head/disk assembly (HDA) with a capacity of 456 Mbytes.
 
The RA81 connects to the controller via the Standard Disk Interconnect (SDI) bus. Additional drives can be connected to a controller to increase the data storage capacity. The RA81 can also be connected in a dual-port arrangement permitting time-shared access by two controllers.
 
The RA81 is a self-contained disk drive with built-in cooling system and DC power supply. An RA81 disk drive subsystem is made up of an SDI controller and one or more disk drives.
 
Key figures are the following.  
 
  
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==Specifications==
  
*Storage capacity of 456 Mbyte in 16-bit word format
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Key figures are the following:
*Heat dissipation is 644 Watt nominal
 
*17.4 Megabit/sec peak transfer rate
 
*28 mSec. average positioning rate (average seek time)
 
*7 mSec. maximum positioning rate (cylinder to cylinder)
 
*50 mSec. maximum seek (innermost to outermost cylinder, in total 1258 cylinders)
 
*8.3 mSec. average rotational latency, rotational speed is 3600 RPM
 
  
== BSD disktab ==
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* Storage capacity of 456 Mbyte in 16-bit word format
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* 1258 [[cylinder]]s
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* 17.4 Megabit/sec peak transfer rate
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* 28 mSec. average positioning rate (average seek time)
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* 7 mSec. maximum positioning rate (cylinder to cylinder)
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* 50 mSec. maximum seek (innermost to outermost cylinder)
 +
* 8.3 mSec. average rotational latency
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* 3600 RPM rotational speed
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* Heat dissipation 644 Watt nominal
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==BSD disktab==
 
<pre>
 
<pre>
 
#
 
#
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</pre>
 
</pre>
  
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==External links==
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* [http://www.bitsavers.org/pdf/dec/disc/ra81/ RA81] - documentation at [[Bitsavers]]
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** [http://www.bitsavers.org/pdf/dec/disc/ra81/EK-0RA81-UG-001_RA-81_Disk_Drive_Users_Guide_1982.pdf RA81 Disk Drive User Guide] (EK-0RA81-UG-001)
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** [http://www.bitsavers.org/pdf/dec/disc/ra81/EK-0RA81-SV-001_Svc_Oct82.pdf RA81 Disk Drive Service Manual] (EK-0RA81-SV-001)
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** [http://www.bitsavers.org/pdf/dec/disc/ra81/MP01359_RA81_Oct82.pdf RA81 Field Maintenance Print Set] (MP-01359)
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* [https://www.pdp-11.nl/peripherals/disk/ra81-info.html RA81 information] - Henk Gooijen's extensive RA81 material
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** [https://www.pdp-11.nl/peripherals/disk/ra-images/ra81-open-model.jpg RA81 internals] - fantastic image of a sectioned RA81 drive
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*  [https://archive.org/details/bitsavers_decdiscRA6vesBrochureAug82_2235969 The RA60, RA80 and RA81 Disk Drives] - combined [[RA60]]/[[RA80]]/RA81 sales brochure
  
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[[Category: DEC Disk Drives]]

Revision as of 15:16, 23 January 2023

4 RA81's in two cabinets

The RA81 is a DEC disk drive, introduced in 1982. It is a moving head (SDI Winchester) fixed disk drive. It has a non-removable media using a head/disk assembly (HDA) with a capacity of 456 Mbytes.

The RA81 connects to the controller via the Standard Disk Interconnect (SDI) bus. Additional drives can be connected to a controller to increase the data storage capacity. The RA81 can also be connected in a dual-port arrangement permitting time-shared access by two controllers.

The RA81 is a self-contained disk drive with built-in cooling system and DC power supply. An RA81 disk drive subsystem is made up of an SDI disk controller and one or more disk drives.

Specifications

Key figures are the following:

  • Storage capacity of 456 Mbyte in 16-bit word format
  • 1258 cylinders
  • 17.4 Megabit/sec peak transfer rate
  • 28 mSec. average positioning rate (average seek time)
  • 7 mSec. maximum positioning rate (cylinder to cylinder)
  • 50 mSec. maximum seek (innermost to outermost cylinder)
  • 8.3 mSec. average rotational latency
  • 3600 RPM rotational speed
  • Heat dissipation 644 Watt nominal

BSD disktab

#
# UCB RA81: use a-b-h-g or a-b-h-d-e-f
ucbra81|UCBRA81|DEC UCBRA81 Winchester:\
        :ty=winchester:ns#51:nt#14:nc#1248:\
        :dt=MSCP:\
        :pa#15884:oa#0:ba#8192:fa#1024:\
        :pb#33440:ob#15884:bb#4096:fb#512:tb=swap:\
        :pc#891072:oc#0:bc#8192:fc#1024:\
        :pd#15884:od#242606:bd#4096:fd#512:\
        :pe#307200:oe#258490:be#8192:fe#1024:\
        :pf#325382:of#565690:bf#4096:ff#512:\
        :pg#648466:og#242606:bg#4096:fg#1024:\
        :ph#193282:oh#49324:bh#4096:fh#512:

External links