test-drb

test-drb@ccmp.vtda.org

101090 discussions

by jnc＠mercury.lcs.mit.edu

> From: Johnny Billquist > But for people who actually wants to read several hundred K of > MACRO-11... Here is your chance... :-) Ah. Was going to ask what the TCP/IP itself was written in. Well, at least it's an 8-bit machine - think about writing a TCP/IP in PDP-10 MACRO... :-) Noel

11 years, 6 months

Dan Tumey

by robert.jarratt＠ntlworld.com

It is David Tumey and he is on the Greenkeys list. Regards Rob > -----Original Message----- > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Bill > Sudbrink > Sent: 14 January 2015 22:24 > To: cctalk at classiccmp.org > Subject: Dan Tumey > > Is he on this list? The University of Iowa's PDP-8 restoration site says he is > producing beautiful replacement Teletype hammer pads: > > http://homepage.cs.uiowa.edu/~jones/pdp8/UI-8/log.shtml > > I'd love to get a few for my tty. > > Bill S.

11 years, 6 months

front panel LED help sought

by alexandre.tabajara＠gmail.com

Jay, leds hasn't changed much from years ago. Electronicaly, i believe any led of same size/format/color will fit. Of course i can dig deeper if you want enviado do meu telemovel Em 14/01/2015 19:25, "Jay West" <jwest at classiccmp.org> escreveu: Yep, I'm still working on "restoration" of the Microdata Reality. I say "restoration", because due to another restoration project that actually has a deadline, I only have time to clean up the microdata and repair just obvious visual brokenness, not actually start testing/repairing it electronically. That will come after the "deadline project" J As most know, schematics and detailed documentation are nonexistent for this machine. I've done the rack, the disc drive, the tape drive, and the power supply. On to the last item, the front panel. Virtually all of the LED's on the front panel board had so much mouse pee that the leads on the LEDS actually corroded through, so I need to replace them all. Without schematics, can anyone suggest how I might go about determining a suitable replacement LED from an electrical perspective? Pictures at www.ezwind.net/microdata/restoration Best, J

11 years, 6 months

Mauchly video uploaded

by evan＠snarc.net

Cctalk'rs, Very exciting news to share tonight. Al Katz and Sol Libes, who co-founded the Trenton Computer Festival based on Roger Amidon's idea, gave we "MARCHins" permission to publish their video of ENIAC's John Mauchly keynoting the 1977 show. It was the first TCF keynote: there wasn't one at the 1976 show. Claude Kagan (a Western Electric engineer who also ran a 1960s/1970s high school computer club here in central New Jersey) gave the introduction. There are also remarks by Kay Mauchly, who was an ENIAC programmer, followed by some audience Q&A. A few minutes of the video are choppy due to the original source. Please share this far and wide! Video is in two parts so here's the playlist: https://www.youtube.com/playlist?list=PL_e5fSxflvrxXO5Ddh9ZXX-cli94zF3Pc

11 years, 6 months

NTP on classiccmp

by jwest＠classiccmp.org

I just noticed that NTP on classiccmp stopped, it has been restarted. My apologies, but you?ll probably want to scroll back ? day to catch any unread messages if you didn?t notice it! J

11 years, 6 months

Free hosting for all classiccmp sites

by jwest＠classiccmp.org

Sean wrote.... ------------ I have Comcast business grade cable Internet to my home and I'm already hosting my own personal site and sites for a few other folks; no data caps; plenty of static IPs; not terribly slow; everything's protected with a Liebert double-conversion UPS... not totally a commercial datacenter in terms of available bandwidth or backup power capacity but nevertheless my uptimes are decent. ------------ I have said many times in the past, but as new list members pop on they are probably not aware of this. I host the classiccmp server (which is not just the classiccmp mailing list, but a growing truckload of user websites that are classiccmp related) gratis. I do not host it on a "Comcast business grade cable internet" connection (there's a contradiction in terms in and of itself...) This is not something I "run out of my home". One of the companies that I own is a hosting provider. We have a rather large-ish datacenter and I have dedicated a set of resources to classiccmp. Our bandwidth is many orders of magnitude greater than a "home or business connection". Not to mention, it's managed bandwidth with load balanced connections to multiple carriers. Our infrastructure is all xenserver based, so spinning up new VM's is a mouseclick. We have quite a few SAN's so storage is not a problem at all. Full HVAC monitoring & control, power backups (oh, and we have two separate powerstations from Ameren UE ON SITE). This infrastructure is professionally managed by my company 24x7. Long story short... it's not a "home" connection. More to the point, since I own the company, rest assured that hosting your site here is not a "till the boss finds out" or "my wife accidentally turned off the computer" type of situation. As a result - I'm happy to host any website, ftp site, wiki, etc. etc. that is classic computer related. As long as it meets that criteria, you can host your site with us for no charge. Best, J

11 years, 6 months

front panel LED help sought

by jnc＠mercury.lcs.mit.edu

> From: Robert Jarratt >> I've replaced LEDs many times without thinking what I am fitting. > "without thinking" is that an impostor pretending to be Tony? :-) :-) Foolish novice! Please consult: http://en.wikipedia.org/wiki/Hacker_koan#Enlightenment for enlightenment. :-) Noel

11 years, 6 months

Answer: Weekly Classic Computer Trivia Question (20150112)

by dpi＠dustyoldcomputers.com

More discussion ensued than was expected for this question. On a minimal 4k machine (no extended memory and no EAE) and no data break devices operating the longest latency would be that of a memory reference instruction with a defer (indirect address) cycle. On a Straight 8 this would be 4.5 microseconds. A single cycle data break device could have delayed the interrupt indefinitely although I know of no such devices. A three cycle break could extend the delay by an additional three memory cycles (4.5 microseconds) for a total of 9 microseconds. If the machine was equipped with an EAE then the Division instruction would have delayed entry of the interrupt service routine by up to 35 microseconds (on a straight 8). I believe this was a 9 microsecond instruction on the 8/e EAE. If the machine is equipped with extended memory then there is the CIF induced delay. CIF is the Change Instruction Field instruction. This instruction only schedules the change. The actual change does not take place until the next JMP I or JMS I instruction. The interrupts are masked by the CIF until the conclusion of the indirect branch. This is because the interrupt handler would not be able to restore the instruction field correctly in this instance. I have been unable to think of a reason why you would ever want to delay the indirect branch although you certainly could do so. That means the sequence CIF followed by a JMS I would only see the additional delay from the JMS I which is the same as the delay from a memory reference instruction with a defer. The JMP I variant would only be 3 microseconds. And the greatest source of interrupt latency on a straight 8 would have been due to the Option 189 which is the low cost A/D converter. This option added the ability to do 6 to 12 bit A/D conversions as a CPU instruction (6004). It performed a typical successive approximation conversion using the MB and AC registers. When 12 bit conversion were selected this instruction would take 56.6 microseconds to execute according to the manual. I don't have a 189 for my straight 8 but I am planning on hunting down the cards I don't have. And the answer Mr Stearns gave for this question was "No matter what it is faster than Windows." On Mon, Jan 12, 2015 at 9:10 AM, Doug Ingraham <dpi at dustyoldcomputers.com> wrote: > This weeks question comes from Warren Stearns. It is a little obscure and > specific to the PDP-8 family of computers. > > What is the source of the greatest latency in the interrupt system on a > PDP-8. > > I have three answers, two of the answers depends on the options fitted to > an 8. > > Why would this have been an important question? Interrupt latency would > be extremely important in the field of data collection which was one of the > principal early uses of these machines. My particular 8 was used for > exactly this purpose in the Summer when it was hauled to a radar site and > collected weather research data for the Institute of Atmospheric Sciences. > I believe it was used for this from 1969 through 1972. I have several > hundred DECTapes with some of this data. The surprising thing is we don't > see any problems reading DECTapes that haven't been out of their box since > the early 70's. > > Doug Ingraham > PDP-8 S/N 1175 >

11 years, 6 months

Dan Tumey

by wh.sudbrink＠verizon.net

Is he on this list? The University of Iowa's PDP-8 restoration site says he is producing beautiful replacement Teletype hammer pads: http://homepage.cs.uiowa.edu/~jones/pdp8/UI-8/log.shtml I'd love to get a few for my tty. Bill S.

11 years, 6 months

Knowledge Base (was RE: Restoration technique [Was: Re: Bay Area: IBM 4341 and HP3000]

by jwest＠classiccmp.org

So.. about this "knowledgebase" of restoration techniques. Apparently new folks don't know and some older listmembers don't remember... We did start a "wiki" for people to post restoration tips, repair tips, etc. This was done about 8 years ago. When I first brought up the idea there was a lot of discussion on the list as to if it was a good idea or not. Many people had very good thoughts as to why it would be wonderful, and many other people had equally good thoughts as to why it would not be wonderful. In any case, I set it up. We found that there was an initial flurry of posting, and then virtually nothing. Statistics showed it was not used very much at all. There were a handful of issues as I recall (not my implementation of it, but in the general idea of a repair/troubleshooting/restoration "wiki"). I only remember one of them at the moment... and that was that someone would post an article without really having detailed expertise in that given area and then someone that DID have expertise in that area would (for lack of a better term) contramand that article or write a separate one with conflicting info which made it hard for a novice to really sift through the information. In short, everyone has an opinion and at times the articles directly conflicted with another and someone seeking knowledge wouldn't know who to believe. That being said, if people really want to give this another try, I would be happy to turn on the old classiccmp knowledge base (I'm 99% sure it's stored but just not turned on), or I could easily have one of my support staff dump a wiki installation to a folder there (under classiccmp) and we could give it a try again. I'm all for it, but for it to be successful - it has to be due to contribution/acceptance by the membership at large. My proclivity at this point would be to install a new wiki and then pull articles already posted in the old "wiki" into it. And yes, if it's to be in the classiccmp.org domain, I'd have to host it. I have not yet seen a scenario where we'd be willing to point an a-record off-site (but that's not to say some future situation might get a different response). Best, J

11 years, 6 months

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