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    The Purpose of this Thread:

    I'd like this to be a place for members to collect and share information allowing identification, duplication, and even replacement of missing DEC keys in a way a Locksmith could accomplish from standards. (without an original to copy)

    I'm beginning with the more difficult ACE keys, but eventually we should be able to collect information on all DEC keys - CPUs, cabinets, etc...

    Members willing to participate and possessing genuine DEC keys, please post them here, by key number, measured dimensions, and photographically if possible. Please mention the precise CPU it fits, if you know.

    The Begining:

    DEC PDP-11 KEY XX2247

    So, with the work on my VAX 11/730, and a PDP-11/10, the subject of keys has come up. I misplaced the key to my 11/70 (like that? MY 11/70 - haven't seen the machine in 20 years) so the VAX 11/730 is the only key I have, but it's reportedly the same one as was the 11/780 and 11/70 keys. (maybe not... read on)

    I see many posts on the internet referring to the Barrel key (aka - Tubular) number XX2247 as being for "most" PDP-11 CPUs and some VAX machines so I assume this is the same as the one I have.

    Looking into it a little, this is what I've found.

    Background Research:

    This type of key was marketed as ACE by Chicago Lock. (Now CompX)

    As was practice of the day, the number imprinted on each key is an INDEX number, which identifies it's geometry in a master list. This geometry is a CODE, consisting of numbers (1-8 ) for pin depths of pin numbers (1-7) and a rotational offset. Supposedly, "FULL SERVICE" locksmiths could make a new key directly from the CODE.

    I've not found the master list on the internet. I don't know if "modern" locksmiths have it any longer. But since I have a key, and it's presumably one of these, I can MEASURE the pin depths and record them here.

    This should enable anyone to have a duplicate made, and to check my key against theirs and identify it as a XX2247 (or not). My key DEFINITELY fits my 11/730, and turns the CPU lock. For the record, there is a stamped number on this key (MRP6231) - however I think it's a duplicated key and not an original number.

    Barrel Keys:
    • PIN Identification: Holding the key looking into the open barrel end, one sees the cuts. These can be symmetrical around the "Tang" or offset "left" or "right". Mine is "Centered".
    • Counting from the Tang - clockwise, the pin locations are numbered 7-1 in decreasing order. (ACE keys are numbered this way, FORT keys are opposite - increasing order 1-7)
    • PIN Depths: 8 Depths are in 0.016" increments, beginning at 1 = 0.016" and ending with 8 = 0.128"

    ACE Depth Code List: (and another)
    1 = 0.016
    2 = 0.032
    3 = 0.048
    4 = 0.064
    5 = 0.080
    6 = 0.096
    7 = 0.112
    8 = 0.128

    Now, for my key: (in inches)

    This would make the ACE depth "code" (pin#:depthcode) for my key 7654321:7557537 (adjusted) with pins "Symmetrical" (aka "Centered") about the tang.

    In the FORT system, that would be: 1234567:6446426 as the depths and pin order are different in that standard.

    Open Requests:
    1. Please post any use of an XX2247 key not listed below
    2. Anyone who has an original DEC key, especially other than XX2247 - please post
    3. Also, if anyone uses this "code" information to have an "original" key made, please report your success or failure here.

    Thank You.

    Note: If there's enough interest in this topic, I plan to ask the admins to make this forum a "Sticky" so the head post(s) can be re-edited and maintained with the currently established "up to date" key information.


    Confirmed ACE Keys and Uses:

    DEC#      ACE CODE           CPU
    XX2247    7654321:5173757    PDP-8 (Classic)
    XX2247    7654321:5173757    PDP-8/e
    XX2247    7654321:5173757    PDP-8/I
    XX2247    7654321:5173757    PDP-8/L
    XX2247    7654321:5173757    PDP-8/m
    XX2247    7654321:5173757    PDP-11/20
    XX2247    7654321:5173757    PDP-11/30
    Plastic   Un-Cut             PDP-11/44 (any ACE key works)
    XX2247    7654321:5173757    PDP-11/45
    ?         7654321:7557537    PDP-11/730  (VAX)
    Last edited by RSX11M+; October 5, 2013, 03:30 PM. Reason: update key list

    XX2247 Key example

    This post at, shows Pete Turnbull taking a similar approach, documenting his XX2247 key depths.

    These are his measurements:

    ACE XX2247
    Key 1    Key 1   Key 2    Key 2 
    0.0770"  1.94mm  0.0785"  1.95mm 
    0.0150"  0.37mm  0.0155"  0.39mm 
    0.1055"  2.68mm  0.1070"  2.72mm 
    0.0435"  1.13mm  0.0455"  1.13mm 
    0.1075"  2.72mm  0.1085"  2.74mm 
    0.0780"  1.96mm  0.0785"  1.98mm 
    0.1075"  2.72mm  0.1095"  2.77mm
    While his purpose was to question the accuracy of his keys, it permits us to convert his measurements to the following "CODE" 7654321:5173757 for two verified XX2247 keys. (confirmed here)

    Based on this, my key is some other DEC key. (VAX 11/730 owners take note)

    Also in that post is dimensional information on another unattributed key:

    ACE XX4306
    0.1070"    2.72mm
    0.0775"    1.97mm
    0.0600"    1.53mm
    0.0615"    1.56mm
    0.0180"    0.45mm
    0.0780"    1.97mm
    0.0780"    1.97mm
    I would list this as ACE CODE 7654321:7544155 for key XX4306
    Last edited by RSX11M+; October 4, 2013, 12:49 PM.





      millimeters inches
      1.95 0.078
      0.4 0.016
      2.75 0.108
      1.15 0.045
      2.7 0.106
      1.95 0.078
      2.8 0.110
      As far as I remember this one came with our PDP-8.


        I've been interested in locks and locksmithing for most of my life, and I'm hoping to enter the ranks of DEC computer collectors in the not too distant future. I don't have any DEC keys yet, but I do have a machine for copying Ace tubular keys as well as a set of tubular depth keys (that is, a set of keys where each one has all 7 positions cut to the same depth, allowing them to be used to cut new keys by code on a plain tubular duplicating machine). Maybe I'll be able to contribute towards this project somehow?


          Originally posted by MattisLind View Post
          XX2247 ... As far as I remember this one came with our PDP-8.
          Thanks for the response and the data point. Can you please tell us which specific PDP-8 model that is (was)?

          Originally posted by NF6X View Post
          ... Maybe I'll be able to contribute towards this project somehow?
          Welcome. It sounds like you'll at least be able to benefit. Potentially, if you can make keys on request, your contribution may be to take orders. I would request that if and when you get to that stage, your keys were marked as DEC keys would be - with the original numbers, but also discreetly marked with your ID somehow so they could be distinguished from originals.


            My ebay MicroVAX came with a similar key that isn't really a key in the usual sense. It looks similar to the keys you mention but it's molded from grey plastic, has only the index pin and no cutouts. The only markings on it are "DIGITAL Antistatic" molded as opposed to engraved or stamped on both sides. The key is used to release a sliding cover that could be used to restrict access to the controls on the side panel.
            "It's all bits on the bus, Cowboy! It's all bits on the bus!" -- Tom Beck, #1ESS Instructor, Southern Bell Opa Locka Training Center


              I can confirm that my XX2247 copy (procured by Crawford about three years ago) that I use in my 8/e is within two thousandths of the others XX2247 measurements. It is a copy made on an ILCO 1137S blank. I used a Starrett No. 449 depth mic.



                If I remember and get around to it, I should compare the depths published here to my depth keys. If they're close, then maybe I should try cutting an XX2247 key by code, and then send it to somebody like Lou to see if it works?


                  I'll gladly test it for you on the 8/e if you like. Someone closer to you in CA will surely volunteer also.

                  Are the blanks still readily available? I'm sure that there are plenty of people looking for this key. For about 20 years I never had one, and was fortunate that my 8/e was locked in the on position.



                    I got my small box of tubular blanks off eBay several years ago. I just checked again, and easily found some there.


                      My PDP-8/M came with a single key, the same ACE XX2247. I didn't feel like taking any chances on losing it so I went to a local locksmith. They made a working copy with no problem. The blank is a 137CLC, Chicago Lock Co. I can get a price if someone needs one. If I recall, it was under $10.

                      I don't have a micrometer to get decent measurements--but they appear close to the ACE XX2247 from Pete Turnbull's Key 1 & Key 2.



                        There's a bloke in France who can cut PDP-11 keys, see his informative page at
                        I ended up borrowing a PDP-11/05 key which was easily duplicated at a 'Mister Minit' key cutter in the local shopping centre.

                        UPDATED in response to RSX11M+'s query - the key is labelled C24 on one side, EDMONDS on the other. They work acceptably, not as smooth as the original but this was to be expected. I used a Dremel rotary brass wire mop to smooth the rough edges.
                        Last edited by 1944GPW; October 4, 2013, 09:06 PM. Reason: Added photos


                          Originally posted by 1944GPW View Post
                          There's a bloke in France who can cut PDP-11 keys, see his informative page at
                          I ended up borrowing a PDP-11/05 key which was easily duplicated at a 'Mister Minit' key cutter in the local shopping centre.

                          Yes, I linked to that site.

                          I'm trying to make an 11/05 (11/10) key myself at the moment... you don't happen to know what blank was used, do you?


                            C24 - Edmonds - Thanks, I'll see if it can be cross-referenced locally.


                              1. I need one of those 11/10 keys too (at the moment I have to jumper around it, sigh)! If someone is prepared to make some duplicates, please count me in to defray costs.

                              2. I can confirm that the XX2247 works with both an 8/L and an 11/20 (early manufacture, labeled simply "PDP-11").