test-drb July 2018

test-drb@ccmp.vtda.org

148 participants
163 discussions

IP address classes vs CIDR (was Re: Reviving ARPAnet)

by jnc＠mercury.lcs.mit.edu

> From: Eric Smith > which would respond to ARP requests for non-local addresses and reply > with the router's MAC address (on that interface), specifically in > order to make classful-only hosts work on a CIDR network. Yeah, Proxy ARP (an early RFC here: https://www.rfc-editor.org/rfc/rfc1027.txt but IIRC it was people at CMU who first came up with the idea; this RFC is >from people at UT-Austin, documenting it) was originally done to support subnetting (see https://www.rfc-editor.org/rfc/rfc917.txt for more) when it was first introduced - for hosts for which people didn't have the source, but needed to attach it to a subnetted network. Subnetting was a stage before CIDR (which took subnetting and Carl-Herbert Rokitansky's 'supernetting' and mushed them together). Noel

6 years

Which Operating System for my DCC-116 E / Entrex 480 / Nixdorf 620 / Data General Nova 1200 clone ?

by cube1＠charter.net

On 10/4/2017 3:33 PM, Dominique Carlier via cctech wrote: > Hi all > > I start here another topic concerning my research about a new Operating > System for my freshly restored DCC-116 E. > > http://www.zeltrax.com/classiccmp_forum/second_boot/04.jpg > http://www.zeltrax.com/classiccmp_forum/second_boot/02.jpg > > I originally intended to install RDOS on my machine but it seems very > difficult to find the files needed to make a system installation tape. > FIRST: If you have drawings for the DCC, please let me know. I have two of them (long in storage in the house, but they ran when I pulled them from their Unitote/Regitel rack a couple of *decades* ago. There is an RDOS - disk images, available at: http://simh.trailing-edge.com/software.html (Top entry in the list) It is about a 2.5MB disk image. I suggest that you might download SimH and that image, configure SimH as a straight Nova (rather than a /3 or /4) and see if it runs that image OK. If so, there you go! Beyond that, I *might* be able to help, but it will depend on what the status of copyright is on what I have, and whether your system can even run what I do have. I am looking into the copyright part of it - that may take a week or two. (This is something I needed to to anyway). In the meantime: Do you have a way to *write* a tape image? I have an AWS format image of an RDOS starter system. Note, however, that the label on the RDOS starter image I have suggests it may only be appropriate for a NOVA 3 or NOVA 4, so it might not run on your system. So, I'd have to take some time to boot it and try and set up a system for a straight Nova. As this would take several hours, I'm not keen on doing that unless you know that one from SimH will not work for you. I also have some OS and compiler DG floppy images, if you have a DG-compatible floppy setup. Several different operating systems there. Same issue: one would have to see how many are compatible with a straight Nova. I have images of the floppies. Diagnostics for DG systems are notoriously difficult to find. I have a few, in listing format. JRJ

6 years, 2 months

Thicknet/10base5 Test Segment: The Cable is In!

by systems.glitch＠gmail.com

All, A few months ago, I mentioned one of my suppliers had Belden 89880 thicknet Ethernet cable. Well, last week I finally made it down to his warehouse and picked it up! The final bits for a test segment came in today, so I set up a little link between my SPARCstation 10 and DEChub 90: https://imgur.com/a/GDUR36j Anyone interested in cable can email me directly (please change the subject line, it'll get binned into my cctalk folder otherwise). I can provide any level of "kit" from just the cable to fully ready to go. I do have a very few NOS Cabletron ST-500-01 transceiver/non-intrusive tap kits as well. Thanks, Jonathan

6 years, 3 months

Strange third party board in PDP-11/45

by jnc＠mercury.lcs.mit.edu

> As to what _else_ it is doing, and why it has the cable to the main > card... I think that it must intercept MSYN from the processor and only > let it pass if there's no hit in the cache. > (To explain why it would need to do that... normally with the MS11, > there's a static partitioning between FastBus memory and UNIBUS A > memory. So when the CPU goes to do a memory cycle, it can put the > address out on both the UNIBUS and FastBus, with the certainty that it > will only get a reply on one. So, my guess was wrong there. I had _assumed_ that when doing a memory operation, the CPU started a cycle on both busses, to minimize the delay on the UNIBUS cycle if the MS11 on the FastBus didn't have that location. (I had previously checked, and there is an 'I have that location' signal which the MS11 sends back, making the concept of a cache possible.) Well, no. In the "KB11-A CPU Maintenance Manual" (DEC-11-HKBB-D), section 7.7.1 ("Bus Control Introduction"), it says: If the address applies to a Fastbus device, that device will respond in time to inhibit the UNIBUS MSYN signal (It turns out the KB11-A is very clever; it has to delay for a bit after asserting the address, etc, signals on the UNIBUS, for de-skew, before it can assert MSYN, and during that delay, in parallel, it checks to see if the MS11 has that location.) So my theory about what that double-card does (prevent an MSYN sent to main memory on a cache hit) is apparently wrong. Which leaves the question of what that card _does_ do... The cache _does_ need to have the A and B UNIBUS tied together, so that it can snoop UNIBUS memory cycles (which are on the A UNIBUS) via the B UNIBUS (which is what it has access to on the backplane), _but_ it doesn't need a special card, with i) active logic, and b) a cable back to the main board, to do that - a regular M9200 will do that. The cable back to the main card, and the logic on the two dual-width cards, mean it wants to interfere somehow in the connection between the A and B UNIBUS. But if not the MSYN thing, what else could it be? I have pondered that question, but I can't think of anything. It can't be doing anything with interrupts or DMA, I would think, so no grant interception. So what else could it be? Anyone have any ideas? Noel

6 years, 3 months

RK05 spindle pulleys - trade 50Hz vs 60Hz?

by gerardcjat＠free.fr

Why don't you simply power it through an inverter that will output 60 Hz, eventually even "down to" 120 V , true sine wave, of course ??? They are not that expensive by now. And be carefull : motor designed for 60 Hz, running "under" 50 Hz, OR THE OPPOSITE, I do not recall !!!, display a significant reduced life time. I have to check which is which, but I know this is a question of saturated magnetic field. Better check first.

6 years, 3 months

VCFMW drop offs, pick ups, visits

by useddec＠gmail.com

I'm looking forward to seeing everyone going to VCFMW. I'm going to try to go up Friday and leave late Saturday. It's always great when people swing by the house, but try to give me some warning, especially with me going up Friday. I hope to have a path dug into my last 25 foot storage unit and retrieve a ton of micro-Vax II parts along with a ton of other items. I still have a few 3000 alphas, about 10 3100s, a few 4000s, 5000s, 6 or so BA11-N (11/03L/23) boxes, BA23s, LA120s, and 1000's of other parts. Also some REMEX interfaces and a bunch of paper tape readers and maybe punches I'm getting tired of looking at. Please contact me off list if you have any requests or questions. Feel free to send me wish lists. Thanks, Paul

6 years, 3 months

Pair of Portmaster II's

by db＠db.net

I have two Livingston PM-11's (http://portmasters.com/faq.html) and I haven't needed either of these in a long time. Is anyone interested in them? Diane -- - db at FreeBSD.org db at db.net http://www.db.net/~db

6 years, 4 months

Australian Computer Museum in trouble.

by geremin＠iprimus.com.au

Australian COMPUTER MUSEUM -- Dispersal Days -- Villawood NSW. We have been told that BULLDOZERS will demolish our Villawood storage space in 2 weeks. We have yet to find a suitable/affordable alternate space so ... "OPEN DOOR DAYS" The old fruit shop at 888 Woodville Road, VILLAWWOOD, will be open for anyone who cares to come and take anything away and help preserve our computing heritage. Hours: Sat 28th/Sun29th 9am to 9pm, then Monday-Friday 10am to 10pm, repeat the next week. Off-street parking, easiest access is from south (Hume Hwy), see Google Maps. Bring your Car, Van or Ute and enough muscle to help empty our shed. Please tell your friends and/or work colleagues. -- <b>John GEREMIN, Honorary Treasurer, 0427 10 20 60.</b> Australian Computer Museum Society Inc. PO Box 4005, Homebush, NSW, 2140. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 4 months

DECstation firmware archive?

by aek＠bitsavers.org

Are the firmware eproms for the DECstation archived anywhere?

6 years, 4 months

Australian Computer Museum - HELP

by geremin＠iprimus.com.au

The building housing the Australian Computer Museum is scheduled to be demolished in 2 weeks. Anyone in Sydney (or nearby) is invited to HELP preserve the collection by providing storage (for doco or big or small items) until we get a proper home. Please email INFO at ACMS.ORG.AU for more details, or call John 0427 10 20 60 in Australia. -- <b>John GEREMIN, Honorary Treasurer, 0427 10 20 60.</b> Australian Computer Museum Society Inc. PO Box 4005, Homebush, NSW, 2140. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 4 months

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test-drb July 2018