test-drb February 2021

test-drb@ccmp.vtda.org

113 participants
93 discussions

by a.carlini＠ntlworld.com

I have three AlphaServer 2100 systems in storage in the UK (Oxfordshire). The storage, however, is due to be demolished (soon, but no fixed date). I won't have room to store these three systems, so if anyone would be interested in offering them a home, then please get in touch! I can probably get some pictures in the next day or two. These systems were SMP Alphas and could sport as many as 4 CPUs. I'm not sure of the configuration of these systems but I can probably find that out soon. They have not been run since ~2003 so they may be in need of some TLC. OTOH they are not rusted to death so you have a chance of getting them back to life. Just so you know what you might be dealing with these systems are about: 700mm H x 430mm W x 810mm L. I can't find the weight in any of my references right now but they are very heavy. Three people can move them up a slight slope with some effort but you would not successfully lift it into a car (assuming that it would fit). I'm planning to dismantle them to move them (i.e. remove PSU/PSUs etc. until they are light enough to move). A tail-lift would probably be the sane way to go (and is, indeed, how they got to their current location. I'm hoping that someone can step forward and offer one or more of these machines a new home. Please contact me off-list (once you're sure you understand what you are getting into :-)). Antonio -- Antonio Carlini antonio at acarlini.com

2 years

H7821 power supply in MicroVAX 3100, SCSI disk enclosures and others

by cctalk＠beyondthepale.ie

The recent discussion on BSC protocol prompted me to dig out my Microvax 3100 with DSH32 synchronous serial interface. It had been idle in storage for several years and it wouldn't power up, only giving a brief flash on the diagnostic LEDs and a quick twitch of the fans. There was a slight smell, like the stale air that comes out of a deflating tyre. I took out the H7821 power supply and found that five identical brown 1800uF 25V electrolytic capacitors on the output side had leaked. The SCSI disk enclosure where the machine's system disk lives required several power cycles to get it to run at all and it died as soon as the disk tried to spin up. It turned out to also contain a H7821 power supply which had a similar issue with the same five brown capacitors, although not as extensive as in the main unit. I found a second disk enclosure which had seen little use and grabbed the power supply out of that to put in the MicroVAX. It worked well enough to test with but there was a ring of goo around the bottom of one of the brown capacitors which was worst affected in the other units. Time to order a batch of replacement capacitors and figure out what else has been damaged. While it is not the worst I have seen, access to these power supplies for repairs is quite difficult and it is really difficult to debug them safely while they are running with the cover off :-( If anyone has anything with H7821 power supplies in them, I suggest checking on these capacitors. If anything with these power supplies is in storage, I suggest ensuring it is stored the normal way up as this should limit the ability of the goo to escape and spread around the power supply. And there I was thought I was being safe enough by removing the nicad battery packs some years ago... Regards, Peter Coghlan.

2 years, 3 months

PDP-11/05 microcode dump?

by jnc＠mercury.lcs.mit.edu

> From: Mattis Lind > Thanks Noel for sorting this out. Eh, de nada. But thank you. >> I wonder if the ucode in the two versions is identical? The uROM chip >> numbers should give it, (if they are the same on both versions, albeit >> in different locations on the board), but I have yet to check. Does >> anyone happen to know? OK, so the situation here is pretty complicated. To start with / make things worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of PROMs. For the data paths board (M7260), both major versions appear to contain the same PROMs (going by the DEC part numbers), but the chip location (Exx) numbers are all different. For the control board (M7261), the C, E ('early' version) and F ('late' version) etch revisions each contain mostly the same PROMs, but apparently with slight differences between the sets of PROMs in each (as reflected in different DEC part numbers). For details see: http://gunkies.org/wiki/PDP-11/05#Control_PROMs to which I have just added all the gory details. As to getting the contents of all of them dumped in machine-readable form - oi vey! >> on the earlier version (prints for that version are in the GT40 prints >> online It turns out that I have hard-copy prints for the "C" etch revision of the M7261, which do not yet appear to be online; the GT40 prints have the "E" etch revision. I will scan the pages for that revision of the board, and put them up 'soon'. (I'm not doing the whole print set, it's about 1" thick, and most of them are for other things anyway, like MM11-L memory, etc.) Noel

2 years, 10 months

Sovier/Russian 132-pin PGA Ceramic IC Packaging

by pbirkel＠gmail.com

In item https://www.ebay.com/itm/265045229011 I am curious as to whether the gold islands on the top-side are functional test-points giving electrical access to the underside pins? Was there a clip designed to attach to the top-side of these chips for use in circuit analysis? Was this design unique to Russian manufacture (I don't recall ever seeing this design previously)? paul

2 years, 10 months

Massbus - was: Re: VAX 11/750

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning > There's a good reason why the big disks on many DEC machines were Massbus > devices until MSCP arrived. It's quite clear on Unibus PDP-11s, which > needed Massbus both for speed and for a cleaner answer to more-than-18 > bit addressing. I follow the first sentence, but I'm confused by the second, especially "a cleaner answer to more-than-18 bit addressing". The UNIBUS MASSBUS controller/adapter, the RH11, only has 18-bit addressing on the main memory side. It does have more than 18-bit addressing on the device side, but so does the RP11 (sort of). Are you thinking of the RH70? That does have access to more than 2^18 bytes of main memory, but that's because it connects to the -11/70 memory bus (as well as the UNIBUS, which is only used for control, not data). Similar questions about the speed point; passing data through an RH11 doesn't increase the speed of the UNIBUS? Yes, the RH70 is faster, but that's because of its connection to the -11/70 memory bus. Noel

3 years, 2 months

ISO: Stabilization feet for DEC H960 rack

by derschjo＠gmail.com

I realize these are uncommon; curious if anyone has a spare pair somewhere (hey, that rhymes.) I'd like to be able to pull out the CPU on my 11/70 without worrying about the whole thing tipping over and crushing people I care about. It's the little things, really... Thanks! - Josh

3 years, 2 months

Any interest in a Floating Point Systems AP-120 array processor?

by derschjo＠gmail.com

I picked this up a number of years ago for reasons that entirely escape me. It's certainly neat, but I don't see myself ever actually using it and it's large and heavy. Documented here: http://bitsavers.trailing-edge.com/pdf/fps/7259-02_AP-120B_procHbk.pdf Mine appears to have a DEC-style interface but I'm unsure what it talks to on the DEC side of things. I can take pictures if there's interest, but it's fairly nondescript, just a large white box with rack-mount ears and a small panel with some switches on it. It's in the Seattle area if anyone wants it, and it's free! Shipping is... not something I really want to think about right now. - Josh

3 years, 2 months

ISO: Stabilization feet for DEC H960 rack

by jnc＠mercury.lcs.mit.edu

> From: Steven Malikoff > I have yet to machine the bolt head tapers to the originals but lost > the photo of one that was posted here some time ago. By "bolt head tapers", do you mean the special bolts with countersunk heads, or the countersunk holes in the extension feet? Whichever it was, I can provide photos and/or measurements, as needed. Noel

3 years, 2 months

DOS/Batch 10 source disks

by aek＠bitsavers.org

Did someone on the list buy the pair of source RK05's on eBay? https://www.ebay.com/itm/PDP-11-Program-Monitor-V10-02-CUSP-and-Device-Driv… I bought the fortran source disk that was listed at the same time, but didn't go after these because of the cost and I may already have it in the archived DECtapes on bitsavers.

3 years, 2 months

Electronics Plus

by jwest＠classiccmp.org

In case this link only made it to discord, I'm (re-?)posting here. Cindy has been extremely helpful and generous and giving of her time to all in this hobby. It is a very worthy cause. https://www.gofundme.com/f/electronics-plus Not too much more to hit their goal. Lets see if we can put them over, I'm pretty sure most of us have benefited from her efforts. Cindy, a few things have changed on my end with retirement, but I may be able to get that website back online for you. Please reach out to me directly and I'll check. Best, J

3 years, 2 months

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test-drb February 2021