Talk:PDP-1

message: Brouhaha, you say, without explanation, "Flexowriters were NOT based on IBM typewriter mechanisms." All I can say is, when I was a PDP-1 hacker, I looked at the insides of a Flexowriter and I looked at the insides of an IBM electric typewriter of the same period and they certainly looked identical to me. And identical to the typing guts of the Sorobans. Whereas a Royal, for example, looked completely different. These are old memories and perhaps unreliable. 
Why do you say the Flexowriters did not have IBM electric typewriter mechanisms? 
Do mean they were mechanically different? Or do you mean they were manufactured by Friden rather than IBM, which could well have been done under a license or something...
I am, of course, talking about pre-Selectric IBM electric typewriters. Dpbsmith (talk) 12:22, 2 September 2005 (UTC)
replies: text: I personally own a Flexowriter from the early 1960s, and also an IBM Model B electric typewriter (the model the Soroban was based on), and although the mechanisms work on the same general principles, they are not identical.  You're welcome to come to the Computer History Museum and inspect the PDP-1 console Soroban and the Flexowriters that the museum has.  --Brouhaha 01:32, 3 September 2005 (UTC)
replies: text: Well, I recently edited the article and put Bob Mast's comments in as a footnote. If you want to tweak it further, to say that the mechanism was "similar to" instead of "mechanically the same as" an IBM typewriter, be my guest. I have a vague idea that the Flexowriters resembled the _crufty older_ typewriters that _less senior_ secretaries used to use in the mid-1960s and that the Sorobans resembled the _spiffier newer_ ones. I'm not a typewriter maven though. As to the Computer Museum, well, I live near Boston, and I visited it when it was in Marlboro and I visited it when it was in Boston--both when it looked like a computer museum and when it looked like Sesame Street, but I don't get out to Mountain View very often. Does it still have the COBOL tombstone? Dpbsmith (talk) 02:17, 3 September 2005 (UTC)
replies: text: Yes, the COBOL tombstone is still there.  Maybe someday it will be accurate.  The Computer History Museum is much more focused on preserving the artifacts, stories, etc. than the Computer Museum was in its later years.  Anyhow. let me know if you do get to the west coast sometime, as we'd love to have you visit, see the running PDP-1, and tell us about your own PDP-1 experiences.  --Brouhaha 06:49, 3 September 2005 (UTC)
thread_title:  Flexowriters and IBM electric typewriters 

message: Several new articles started last summer have been tagged merge because of what appears to be lack of input (I have contributed only what I learned from the restoration video). What do you think?
Merge into new article PDP-1 Software:
* Colossal Typewriter, Talk, Comments
* Expensive Desk Calculator, Talk, Comments
* Harmony Compiler, Talk, Comments
* T-Square (software), Talk, Comments
* TJ-2, Talk, Comments
Merge with Spacewar
* Expensive Planetarium, Talk, Comments
Merge with TX-0
* Expensive Tape Recorder, Talk, Comments
Thank you for your thoughts. --Susanlesch 12:32, 28 December 2006 (UTC)
replies: text: * In case it helps, I also asked this question in the WikiProjects that looked closest, Early Computers and Computer science (and also asked if there is a Software WikiProject). --Susanlesch 12:38, 28 December 2006 (UTC)
replies: text: *I will remove the merge tags since there is no support. If you should have comments later feel free to leave them on my talk page. Best wishes. -Susanlesch 05:58, 2 January 2007 (UTC)
thread_title: Software

message: I don't agree with the removal of these comments by user Asenine. The comments by Kotok put the PDP-1 into historical perspective, and the fact that they are being made by a PDP-1 pioneer gives them some weight. Dpbsmith (talk) 23:09, 10 August 2008 (UTC)
thread_title: Alan Kotok comments in "current status"

message: The article claimed that it had the equivalent of 9 kilobytes = "9000" bytes.  This seemed dubious to me, especially since redefining pibinary prefixes wasn't even tried before 1999, and especially memory sizes used, and use to this day, binary kilobytes rather than drivemakers' ones.  Somehow, nearly every single reference refers to "kilowords" without spelling out the number.  After viewing a few dozens of pages, the only reference I found was [] which describes the address space which might be different from physically installed memory.  Still, it would be strange for these two to differ without a need, and it's consistent with what "kilobyte" meant for all those years.  Thus, I didn't spend more time and replaced it in the article.KiloByte (talk) 09:34, 2 March 2011 (UTC)
replies: text: I think you're missing the point of the byte equivalence. It's just to provide a comparison to modern computers. In terms of number of bits, it's exact: 4096*18 = 9192*8, but since the word organization is different such comparison has limited value. We should also be clear that we are talking 8 bit bytes.--agr (talk) 20:16, 3 July 2011 (UTC)

text: Regardless, someone needs to fix the egregious error of "six-bit bytes". That's a contradiction in terms. What is probably intended, is "six-bit words". 222.154.87.53 (talk)  —Preceding undated comment added 03:19, 8 December 2015 (UTC)
replies: text: Given that words on the PDP-1 were 18 bits long, clearly "six-bit words" was not what was intended.  The system was not byte-addressable; the 18-bit word was the smallest addressable unit of memory, but it didn't use 18-bit characters, so the smallest addressable unit of memory was not the same as the unit of memory used for a character. Guy Harris (talk) 04:16, 8 December 2015 (UTC)

text: A byte is not the same thing as 8-bits. A byte is just a chunk of data that can hold a small amount of data. Computers in the last 30 years have standardised on 8-bit bytes but in the 1960s bytes were often 6, 7, 8 or 9 bits long.  Stepho  talk  04:35, 8 December 2015 (UTC)

text: The later PDP-1s had the LCH and DCH instructions, which addressed 6-bit bytes.  See <http://archive.computerhistory.org/resources/text/DEC/pdp-1/DEC.pdp_1.1964.102652399.pdf>.  John Sauter (talk) 05:11, 8 December 2015 (UTC)
thread_title: Memory size

message: I'm inclined to replace the main photo for this article with :File:Steve Russell and PDP-1.png. I cropped it from a more distant shot and I think it's a better picture of the PDP-1, while avoiding the fair use issue with the current shot. I'm raising the issue here first since the current shot could be deleted from Wikipedia if we remove it from this article.--agr (talk) 20:16, 3 July 2011 (UTC)
replies: text: Did it.--agr (talk) 02:40, 6 July 2011 (UTC)
thread_title: New main pix?

message: Ebaychatter0 (talk) 20:40, 6 September 2012 (UTC)
replies: text: The oil in fingerprints is slightly acidic. So it is common in museums (the caption says the picture was taken in a museum) for anybody handling the artefacts to wear gloves.  Stepho  talk  22:46, 6 September 2012 (UTC)
thread_title:  What's with the gloves the gentleman in the pictures is wearing

message: If anyone wants to do some garbage mining, there is a 4th example of the PDP-1 at the dump in Sudbury. This machine originated at Chalk River where it was used for years until they could no longer supply it with the germanium transistors. They cut all the internal cables and shipped it to Science North where it was the centrepiece of a display on information technology in the 1980s. SN dumped it some time in the 90s, the guy I emailed wasn't sure, and it ended up in the dump. Maury Markowitz (talk) 21:00, 8 November 2014 (UTC)
thread_title:   A 4th example... 

message: In 1978, the MITERS (MIT Electronics Research Society; the electronics club) possessed a PDP-1 and a PDP-7.  I believe the PDP-1 was the original one given to MIT by DEC.  A trade was then engineered with DEC:  They were thinking of starting up a Computer History Museum in Boston, which later occurred.  The '1 and the '7 were traded for about 40 pallets of scrap computer equipment, including some PDP 11-34's, perhaps part of a PDP-11-45 (?), some 11-03's, at least one 300 lpm printer, and various other computer hardware.  A Senior in MITERS at this time was Jordin Kare.  Perhaps this is him: https://en.wikipedia.org/wiki/Jordin_Kare      Sluefoot (talk) 04:45, 5 October 2015 (UTC)
thread_title:  1978 Trade of PDP-1 and PDP-7 

message: The newly-added sidebar says that the operating system for the PDP-1 is the BBN Time-Sharing System.
This is somewhat misleading.  
DEC shipped an assembler, a debugger, some utilities and diagnostic software on paper tape.  They all ran stand-alone.
As far as I know, the BBN software was only used at BBN.  At Stanford we wrote our own time-sharing system, which was only used at Stanford.
I expect other customers wrote their own software based only on the software shipped by DEC.
John Sauter (talk) 19:34, 29 August 2020 (UTC)
replies: text: This was one OS that was available/created for the PDP-1. If there are others, please add them to the infobox. Thanks. Ghettoblaster (talk) 19:58, 29 August 2020 (UTC)
thread_title:  Operating System 

message: While many computer history sites describe the PDP-8 as the first minicomputer, this article lists the PDP-1 as a minicomputer. While it seems DEC starting using the term minicomputer only in the 60's and thus by their standards the PDP-8 was their frst minicomputer, it also seems we have classified the PDP-1 as a minicomputer so maybe the idea that this is the first minicomputer should be included in the article unless another contender existed in 1959. Notcharliechaplin (talk) 03:19, 2 September 2022 (UTC)
replies: text: It's a bit of a grey area. minicomputer says that (compared to a mainframe of the same time), a minicomputer must be cheap, small, general purpose instruction set (ie not specifically accounting or scientific instruction sets) and able to connect to many 3rd party peripherals (ie, not tied to only products in its line). The PDP-1 comes close except possibly for its size - small compared to many mainframes but still large compared to something like the PDP-8 or even the PDP-5. That may or may not be excused by the time difference between the PDP-1 and PDP-8 (newer = smaller).  Stepho  talk  05:37, 2 September 2022 (UTC)
replies: text: The PDP-1 was also expensive compared to the later mini computers.  It was like the CDC-160A but with 18-bit memory and built into standard racks.  I think it deserves to be called an ancestor of the mini computer.  10:57, 2 September 2022 (UTC)
replies: text: True, it was more expensive than later minicomputers (eg 1965 PDP-8 for $18,500). But it was also a lot cheaper than mainframes from its own time. 1959 PDP-1 for $120,000 vs 1957 IBM 709 for $1,200,000 .  Stepho  talk  11:44, 2 September 2022 (UTC)
replies: text: Yes, and it therefore had a place in the market.  However, I don't think it can properly be called a minicomputer, considering how that word was defined.  John Sauter (talk) 18:52, 2 September 2022 (UTC)
replies: text: Really? Considering how a minicomputer is defined (see my first comment), it looks to be a perfect fit - compared to mainframes of its time it is cheaper, smaller, general purpose and easily connectable to outside equipment. Also, it only required single phase mains power and air conditioning was not required.  Stepho  talk  01:11, 3 September 2022 (UTC)
replies: text: According to the definition described in the Minicomputer article you cited, the DEC PDP-1 is too expensive to be a mini computer, even though it is less expensive than the IBM 7090.  The article says a minicomputer costs less than $25,000 whereas the PDP-1 costs $120,000. John Sauter (talk) 13:19, 3 September 2022 (UTC)
thread_title:  First minicomputer?