test-drb

test-drb@ccmp.vtda.org

101090 discussions

by charlesmorris800＠centurytel.net

Thinking I had an easy solution to the missing outer slide, I ordered a $40 pair of new heavy-duty rack slides from eBay. Beautiful pieces and ball-bearing slides, decent quality hardware too. Only had to drill a couple of holes in them so they'd match the drive chassis, mounted everything up, and then discovered that they were 1/4" too narrow, no matter how I arranged the brackets, and the drive wouldn't slide between the rack rails. Crap! So I bought two 24" pieces of 2 x 2 x 1/8" angle iron at the local steel place for a whopping $1.40, drilled four holes in each, sanded off the scale/surface rust, bolted them to the rack and slid the drive right in. You can't even see the "homemade" part unless you're really looking, too. Should've done that to start with. If I ever need to service the drive, I'll just slide it back out and set it on the bench... http://s1181.photobucket.com/user/DrCharlesMorris/media/PDP-8/P09-29-15_19.… http://s1181.photobucket.com/user/DrCharlesMorris/media/PDP-8/P09-29-15_19.… However, if anyone should stumble over a set of stock RX sliding rails I'd be interested for the sake of originality ;) Jay, let me know exactly what measurements you would need. There's a pretty good view of the inside rail on the second pic. thanks Charles

10 years, 7 months

VMS and supported VAX hardware

by pontus＠Update.UU.SE

Hi Is there a table of VMS versions and hardware that they support. I know that 7.3 is the last that supports VAX. But before that, are there limitations to what versions run on which hardware. For instance, would VAX/VMS 1.0 run on a VAXstation 4000? Or would 7.3 run on a 11/730? A somewhat open ended question, but I'm rather clueless to the whole thing. Also, what separates MicroVMS from VMS? Thanks, Pontus.

10 years, 7 months

PDP-11/10 repair started

by jnc＠mercury.lcs.mit.edu

> From: Tony Duell > if it behaves as you describe, it would appear that if placed at the > remote end of the bus it could lock the bus by forcing SACK/ asserted > (as the M9302 does) if a grant chain is open [and there's a board with > a pull-up on the grant input just after the break], whereas if it is > placed at the CPU end it can't. YP;IF. But yeah, good point - this smarter board actually works _better_ at the start of the bus, than at the end. Noel

10 years, 7 months

Writing SCSI 9-Track Mag Tapes from Windows/DOS

by marc.verdiell＠gmail.com

John, Your program worked beautifully writing a SIMH format file on my HP 88780 tape! Thanks a million. Nothing like sending direct SCSI commands to tape >from DOS. Drivers are overrated ;-). Marc ================================ Date: Sat, 3 Oct 2015 02:52:36 -0400 From: John Wilson <wilson at dbit.com> My "ST.EXE" program (available from http://www.dbit.com/pub/ibmpc/util/ including source) runs on real DOS (not Windows) and can write from an E11-format .TAP file (which SIMH uses a garbled version of, but they're interchangeable for *even* record lengths which are 99% of the universe) to a real tape[...] John Wilson D Bit ===============================

10 years, 7 months

Swedish Election Vigil 1968, 1976 and 1982

by mattislind＠gmail.com

I just found these on SVT ?ppet Arkiv (Open Archive). Aside from the fact that they are fascinating time documents (cloths, haircuts, way of speaking), these are a little bit of interest to this community. I guess that since computers were not very commonplace at that time, SVT really liked to emphasize how modern they were to actually use computers. In the 1968 they show a guy that explains that the terminal is connected to a (IBM) 360/40 computer. Later on the actual machine is shown. Apparently they replaced IBM by DEC in 1976 since they are showing off two PDP-11/40 this time. And in 1982 they put the machines almost on the scene. http://www.oppetarkiv.se/video/2260421/valvakan-1968 http://www.oppetarkiv.se/video/2432414/valvakan-1976 http://www.oppetarkiv.se/video/2243834/valvakan-1982

10 years, 7 months

PDP-11/10 repair started

by jnc＠mercury.lcs.mit.edu

> From: Tony Duell > Converting between genuine 20mA loop and RS232 is not that hard. Yes, but I'm i) lazy, and ii) overwhelmed with other projects! :-) >> there's a 'SACK Timeout Module' (M8264) which I think performs the >> same function, but at the _start_ of the bus. (I say 'think' because >> this module is poorly documented - e.g. I don't know of anything which >> definitely states which slot to plug it into.) > I remember a 4 bit counter and LEDs, possibly to count errant grants Yeah, that LED counter looks like a nice feature; I should find one, play with it. > I always assumed it went in the last SPC slot Well, looking at the print (it's in the 11/34 Vol. 2 set that's online), it looks like it should work plugged in anywhere; the circuit just seems to look for any BGn/NPG that's been on 'too long', and when it sees one, asserts SACK. More complicated than the M9302 circuit, which depends on being last, plus they could cram that onto the terminator, is probably why they switched to the M9302 approach. Noel

10 years, 7 months

PDP-11/10 repair started

by jnc＠mercury.lcs.mit.edu

> From: Tony Duell > Yes, it is a pity that the later board set (a) has the jumper to > disable the built-in console port and (b) has the switchable divider > allowing higher baud rates so you generally don't need to :-) Well, except for those of us who don't have any 20mA gear, and want to standardize on EIA... :-) > Adjusting the RC clock is not hard given a frequency counter, and it > doesn't have to be that precise. The prints actually give the time for the pulse width on the two different speed groups, so a well-calibrated 'scope should do it. >> So, how did the M9302 see a 'grant' to start the whole process? Noise >> on an open input? Or maybe it powers up in that state? > The grants are the only (I think) unibus signals to be active high. Yup. A source of great confusion to me when I started working with the QBUS, where they are asserted _low_! I'd done a couple of DMA network interfaces on the UNIBUS, and so was totally familiar with how it worked, and when I recently switched to QBUS (I had used LSI-11's extensively BITD, but not done any hardware on them), that (and a few other similar quirks) really threw me until I got a grip on them! > So if the grant chain is open at any point, the next device along > (which might be the terminator) will have a grant input which is pulled > high by the pull-up resistor. Not always! Some devices (e.g. KW11-P) do have a pull-up, but others (e.g. DL11) only have a pull-down. I looked through a couple of UNIBUS handbooks, to see if there was a spec for how to terminate a grant line, and there isn't, which probably explains the variance in practice. But any which do have a pull-up will generate a bogus 'grant' when there's a break in the grant line between them and their upstream. But my theory of noise on an open input may not apply (unless there are devices with _neither_ pull-up not pull-down - I'l too lazy to exhaustively look at UNIBUS device prints ;-). > when that device gets the grant signal it will handle SACK and also > will not pass the grant on to subsequent devices ... So obviously there > is no way the grant should get all the way to the terminator. But in > some cases (I think a device deasserting the request before it gets the > grant is one) the grant can get all the way along the bus. Exactly. Device is requesting interrupt, but is e.g. reset at the same time the CPU grants the interrupt - result, unwanted grant. > I am not sure why that was deemed to be a problem on later machines and > not older ones (which run quite happily with the M930 terminator at > each end of the bus) I think the deal is that an un-wanted grant can cause things to come to a halt until a 'grant timeout' (the '75 Peripherals Handbook says this is 5-10 usec) happens, so the M9302 speeds that up. Interestingly, I think the M9302 was a _later_ solution to this problem in the 11/34. In the early ones, there's a 'SACK Timeout Module' (M8264) which I think performs the same function, but at the _start_ of the bus. (I say 'think' because this module is poorly documented - e.g. I don't know of anything which definitely states which slot to plug it into.) Noel

10 years, 7 months

PDP-11/10 repair started

by henk.gooijen＠hotmail.com

I have spent some time on the ill PDP-11/10 this weekend. I have this machine already a few years, but I recently got an empty H960 rack, which would be the perfect home for this PDP-11/10. When I picked up this 11/10, the story with it was "not good". "We put the boards in the backplane and switched on the machine. When we saw smoke, we turned it off. We did not know that the boards had to go in specific slots ..."! This machine is an 11/10"S" with 16KW core in the 9-slot CPU backplane. So, possibly the +20V core supply voltage fried ICs. However, a visual inspection did not show any blown ICs. After removing all boards (stored in ESD-safe bags), I first checked the power supply. All voltages are present on the backplanes. DC LO and AC LO are at 4.6V and have a ripple of 130 mV. Seems acceptable to me. Next, I placed the two CPU boards in the backplane. Of course in the correct slots :-) and connected the console ribbon cable. Power on... The RUN LED stays on. Alas, it is not the infamous NPG problem. The console is not responsive, although ENABLE/HALT and then START makes DATA/ADRRS LED 0 go on. But that's all. Seems like some fault finding is needed in the CPU and console. I downloaded "DEC-11-H05AA-A-D_1105um.pdf". In the back are some tests that you can do. I hope to find the problem by elimination. Chapter 6.11 describes a few useful checks to verify the console stand alone. Great! All 8 tests check out just fine, but ... the data pattern on the LEDs is "inverted"! The manual says for test numbers 5, 6, 7, and 8 that the LED pattern must be 052525, 031463, 007417, and 0003777 respectively. I got exactly the opposite data: 125252, 146314, 170360, and 177400. Looking at the schematic I could only explain that by a defective 7404 hex inverter, no longer inverting the input signal. But that seemed too weird to be true, and I was not sure whether that would be a correct assumption anyway. Back home I downloaded "EK-KD11B-MM-001_Jan75.pdf" as a preparation to some microstepping/debugging of the CPU. To my surprise, in the back is a chapter 5.11 "Console maintenance". It describes exactly the same tests, but now the LED data is different ... it is what I am seeing! So, I am happy to say that the console is eliminated as a problem source. I guess that the first manual is not for the 11/10 "S" version, although it surprises me that there would be a difference in the console hardware. I dug up 3 double-width extender boards and the KM11 maintenance panels, getting ready to do some microstepping as described in the manual(s). Keeping both manuals side by side! If you have some ideas how to proceed checking the CPU, I'm all ears! greetz, - Henk, PA8PDP

10 years, 7 months

COS-310 "BAD DATE"

by michael.99.thompson＠gmail.com

> > Date: Sun, 4 Oct 2015 15:01:46 -0500 > From: Jay Jaeger <cube1 at charter.net> > Subject: Re: COS-310 "BAD DATE" > > I doubt that any PDP-8 family OS checks for licensing of any sort. > > Back in those days, DEC used the format DD-MMM-YY for dates, so try > something like: > > 04-OCT-78 > > JRJ > Thanks Jay, that worked! It is different syntax from the COS 300/310 manual that I have. Time to find a different COS manual. -- Michael Thompson

10 years, 7 months

Trivia Question: Pixar Image

by michael.99.thompson＠gmail.com

> > Date: Mon, 5 Oct 2015 10:10:52 -0500 > From: Ben Sinclair <ben at bensinclair.com> > Subject: Re: Trivia Question: Pixar Image Computer > > Are any Pixar Image Computers in the hands of collectors? I would love > to have one of those, even if it didn't do anything! > > -- > Ben Sinclair > ben at bensinclair.com > The RICM has two: http://www.ricomputermuseum.org/Home/equipment/pixar-image-computer -- Michael Thompson

10 years, 7 months

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