test-drb

test-drb@ccmp.vtda.org

101090 discussions

by jnc＠mercury.lcs.mit.edu

So, the MM11-U manual (EK-MF11U-MM-003) describes (pg. 3-12) a set of jumpers (W5-W7) on the G235 card (X and Y selection line current generators - those for the inhibit lines are on the G114) which adjust the bias current for the selection line generators. It goes on to say: "Jumpers W5-W7 are factory cut to adjust the bias current to its optimal value and they should not be changed." There's apparently a similar adjustment for the timing of the sense strobe (although I can't find the description of that circuitry). So I have two observations, based on this. The first is that the original procedure for setting those jumpers is likely lost, it's probably only in some internal DEC documentation. The manual says (Section 5.4.2, "Sense Strobe Delay and Drive Current Adjustments"): "Correction of any failure in either the sense strobe delay or drive current circuits on the G235 module that would require reconfiguration of the jumpers within these circuits should _not_ be attempted in the field. Replace the faulty module with a spare G235 module and return the faulty G235 module to the factor for repair." These cards are old, component values may have drifted, and so perhaps these might need to be adjusted - but we'll need to work out a procedures for doing so, if so. We _do_ seem to have a test to know _if_ the bias current is properly adjusted - see Section 5.3.4, "Drive Current Checks", and also for the strobe delay (Section 5.3.3, "Sense Strobe Delay Checks"). So I guess in theory, if a G235 card fails one of these tests, we could change the smallest value jumper, and see if that made things worse or better, and then loop. So perhaps all is not lost. The second is that I was worried that these boards were 'tuned' to be part of a set. E.g. one of the components, in the circuit that the W5-W7 jumpers are part of, is a thermistor on the core stack board. I couldn't tell if the jumpers were just for dealing with component variations on the G235 board, or if they also include variation elsewhere - i.e. that MM11-U's came as tuned board sets which should not be 'mix and matched'. However, that second chunk of text I quoted alleviated that concern: apparently one _can_ replace one G235 with another, without swapping out all the boards in the set. Which means that the 'mixing and matching' that has happened to these boards since they were removed from their machines (I myself am guilty of this - I pulled a couple of MM11-U sets, and didn't carefully keep the boards in their original sets) has probably not caused any problems. Noel

9 years, 9 months

cctalk Digest, Vol 20, Issue 29

by fred＠MISER.MISERNET.NET

On Mon, 29 Feb 2016 cctalk-request at classiccmp.org wrote: > From: Murray McCullough <c.murray.mccullough at gmail.com> > Subject: Techno-savvy... > Message-ID: > <CAMvyYF-YXr8XFD4q9d1uZrOBBfUgnS=e=NTM8zSGTermw-tT2A at mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > What is a techno-savvy student? Can classic computers possibly give an > answer? I used early microcomputers in my electronics classroom I > taught in the 70?s. Computers back then were rather primitive, not > much better than calculators, but did mimic human learning ? well [story cut] I liked this story, reminded me of my education in the late 80's early 90's - I was the "computer go to guy" so instead of the shiny new PS/2's the district had recently purchased they "stuck" me witth the 5150 in the back that no one wanted to use. The things I was able to make that thing do with just two floppies.... :) > > So what is a techno-savvy student now: Conversant in using a > technological gadget to enhance his/her life? Or being able to build a > computing workstation in high school? Or for simply possessing a basic [chop] Whenever this comes up in the context of today's youth (where they tell me they'll take my job one day) I just have to laugh. The vast majority (not all, as that would be unfair, and I have met some younger than me folks that know their stuff) of youth today know how to USE the device, but not necessarily how to fix it if it breaks physically or logically (I'll leave out that fixing of these tablets/phones/pads physically is usually a board swap ....). As Kirk said in Star Trek II, The Wrath of Khan, "You have to learn WHY things work on a starship." Fred

9 years, 9 months

'motherboard' etymology

by jules.richardson99＠gmail.com

Does anyone know the origins of the term 'motherboard'? I've always associated it with computers and assumed that it started appearing somewhere around 1980, with the fading out of passive backplane systems and arrival of machines which put more functionality onto a 'core' PCB into which other cards were plugged. I don't recall ever seeing it used when referencing earlier big iron, but maybe I've just missed it. I had the case lid off a Fluke digital multimeter which hails from 1972 earlier, and was surprised to see it written as part of a warning there ("ensure that all cards are securely plugged into the motherboard before applying power", or similar - unfortunately I didn't grab a photo at the time). cheers Jules

9 years, 9 months

R: CP/M version 2.1 found

by supervinx＠libero.it

Where do you live? I guess I'm too far to help, but I'd like to have that image and look into it... -------- Messaggio originale -------- Da: David Griffith <dave at 661.org> Data:29/02/2016 09:24 (GMT+01:00) A: cctalk <cctalk at classiccmp.org> Oggetto: CP/M version 2.1 found I found an 8-inch floppy disk labeled with "CP/M V2.0 9/4/79" which is crossed out and replaced below with "CP/M V2.1 7/13/80".? I don't see mention of version 2.1 at http://www.cpm.z80.de.? Do I have something unique?? Who can I trust to image this and put the contents on the net? -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

9 years, 9 months

3B2 Diagnostics

by lists＠loomcom.com

Hi all, There's an image of a 3B2 Diagnostics disk floating around, but I'd like to try to confirm what model of 3B2 it was built for. I'm trying to run the "filledt" program from this diagnostics disk on my 3B2/400 emulator, and seeing some REALLY weird behavior. There are several ways to transfer control in the WE32100 CPU. You can CALL a procedure, which saves minimal state; you can GATE to a procedure, which is what interrupts to, and save more state; or you can CALLPS, which is a full process switch and saves the most state. My simulator can't run the "filledt" program because it is trying to CALL a ROM routine that expects to have been GATE-ed to. The procedure looks back in the stack for the last saved PSW, which isn't there. Sorry for the technical wall of text, but long story short: I don't know whether there is a bug in my simulator leading to this behavior (likely), or whether the 3B2 Diagnostics disk was built for the model 500 or 1000, which have totally different ROMs with different procedures at different vectors. Does anyone have a 3B2 diagnostics disk that is 100% verified to have come with a 3B2/300 or 3B2/400? -Seth -- Seth Morabito web at loomcom.com

9 years, 9 months

MM11-U/UP core memory backplanes

by jnc＠mercury.lcs.mit.edu

> From: Bill Degnan > I will see what else I have available. As far as I have been able to determine, the only backplane that supports the MM11-UP is the MF11-U backplane. Does anyone know of anything else that does? Noel

9 years, 9 months

Fw: new important message

by julian＠twinax.org

Hello! New message, please read <http://hydrodevices.kiev.ua/means.php?4w0> julian at twinax.org

9 years, 9 months

CP/M version 2.1 found

by dave＠661.org

I found an 8-inch floppy disk labeled with "CP/M V2.0 9/4/79" which is crossed out and replaced below with "CP/M V2.1 7/13/80". I don't see mention of version 2.1 at http://www.cpm.z80.de. Do I have something unique? Who can I trust to image this and put the contents on the net? -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

9 years, 9 months

MM11-U/UP core memory backplanes

by jnc＠mercury.lcs.mit.edu

> From: Bill Degnan > My thought is that with my PDP 11/05 with S chassis / BA11-K. Urr, if you're talking about the backplane the CPU is in (which can hold one MM11-U), I think you're out of luck: there's no slot for the M7259 parity controller to plug into (at least, one the one in the -11/05S-10S manual). Noel

9 years, 9 months

Dumb Terminal games (was Re: Looking for a small fast VAX development machine)

by ethan.dicks＠gmail.com

On Tue, Feb 23, 2016 at 12:38 AM, Richard Loken <rlloken at telus.net> wrote: > On Mon, 22 Feb 2016, Mouse wrote: > >>> Computer games require all you can give them [...] >> >> Only if your idea of "games" is "slick-looking realtime 3D-rendering >> games". There are lots of games that work perfectly well on 3100-class >> (and even slower) machines, such as roguelikes (rogue, larn, hack, >> etc), text adventures (ADVENT, DUNGEON, etc), phantasia, Seahaven, >> Klondike...the list is long. > > But those are Computer Games! Not computer games. It is a long time > since I have played rogue. I've been meaning to ask this question since I started cleaning up terminals this year... what are some favorites? Some of the obvious classics are: Adventure Zork (and anything else on a Zmachine) Scott Adams Adventures Wumpus Anything in Dave Ahl's "101 BASIC Computing Games" Empire Star Trek rogue/hack Larn/Ularn But what are some other favorites? I've been running a monthly "retrogaming night" at our Makerspace and so far have brought out a C-64, a PPC Mac, and an 8032 PET. I'm looking to add a PDP-8 (via Oscar Vermuelen's PiDP-8, for portability) and (at first) a simh RT-11 box and/or VAX running VMS, though I have plenty of real DEC gear - it's a matter of transport and storage space). I have a VT220 and an IBM 3101 (very VT52-like with a working terminfo entry) already on site and can add additional terminals if this becomes popular (I may drag in a VT52 just for the excuse to clean one up). I have the Commodore end pretty well covered. I'm looking for suggestions for 80x24 text games that can be played on an ANSI (VT100) terminal and especially non-ANSI (VT52 or that IBM 3101) on Unix/Linux, VMS, and RT-11. So in general, anything that uses curses or direct ANSI sequences or just spews text to a glass tty. -ethan

9 years, 9 months

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