test-drb November 2014

test-drb@ccmp.vtda.org

200 participants
279 discussions

by jnc＠mercury.lcs.mit.edu

Does anyone know if an ECO exists to convert a REV11 board (M9400) to 22-bit, in the same way that an ECO exists to convert BDV11's to 22-bit? (On the BDV11, there's a resistor pack with 4 unused pull-up/down pairs, making it a really trivial ECO.) Noel

11 years

ICL Quattro

by supervinx＠libero.it

Hi! Does someone have some links or manuals about the ICL Quattro model 49 PC? I serviced the PSU, but have no response from the serial ports on the back. Can't say what the port numbering is and if they are DCE or DTE (I assume 9600,8,N,1, may be I'm wrong...). Thanks! -- Vincenzo (aka Supervinx) --==ooOoo==-- My computer collection: http://www.supervinx.com/Retrocomputer --==ooOoo==-- You can reach me at: www.supervinx.com www.facebook.com/supervinx http://www.youtube.com/user/supervinx http://www.myspace.com/supervinx

11 years

PDP-11/23 Debugging

by jnc＠mercury.lcs.mit.edu

> Common practise is to set the vectors at X to point to X-2, and put a > HALT instruction in X+2. Ooops, typo. That first "X-2" should be "X+2". Noel

11 years

PDP-11/23 Debugging

by jnc＠mercury.lcs.mit.edu

> From: Ben Sinclair > It halts back to ODT at 00104 Depending on how the vectors are set up, that could be an unhandled clock interrupt. Common practise is to set the vectors at X to point to X-2, and put a HALT instruction in X+2. 0100 is the line clock interrupt vector. > there is a strange modification... On my original M8186, there is a > capacitor on the left, after the first row of chips, when looking at it > from the tab side. You mean the component side? > The "new" one has that capacitor replaced with a piece of perfboard > with two smaller capacitors, and a two pin connector. I have no idea > what that might be Maybe the electrolytic failed, and the person couldn't find the right size replacement, so used two smaller ones in parallel? > When I run the program, it halts at 000014. That means it trapped through location 010 (illegal instruction); the vector there points to location 012; it executed the HALT instruction at 012, and stopped with the PC containing 014 (the location of the next instruction - see the description of the HALT instruction in most versions of the PDP-11 processor manual). To find out the location of the illegal instruction, you need to look on the stack: R6 (the SP) will point to to top of the stack, and the PC and PS at the time the illegal instruction were seen will be the top two things on the stack. (I forget whether they are in (SP) and (SP+2), or (SP+2) and (SP+4). And I forget whether the saved PC is the address of the bad instruction, or if the PC has already been incremented to point at the next instruction.) But I'm not sure that's really going to tell you much. If it's a hardware flaky, the fault may be happening on a perfectly good instuction. > the error address should be in R1, which reads as 004330. I did try and > write to that location, and it reads back fine. But if you trapped through 10, that's not caused by that memory location being a problem. > I'm confused though, because it halts at 000014, but that program > doesn't have an instruction at 000014. .. I would have thought it would > halt on some location that actually had an instruction. After a HALT instruction, the PC points to the _next_ instruction after the HALT. So the HALT was at 012. > What exactly does the aux switch on the front panel control? I assumed > it was power to the AC plug on the back of the machine, but it must do > something else. Well, it depends on what model of box you have, and how it's configured, but on standard DEC LSI11 boxes (the ones with three switches; Restart, Run/Halt, and Aux), the Aux can be configured (and normally is) to turn the Line Clock off and on; the Aux power thing is an optional behaviour. That would definitely fit the symptoms and behaviour you describe. > From the documentation, I don't see that it does anything other than > control that AC plug. There's documentation somewhere (don't recall off the top of my head - it won't be in the processor card stuff, it will be in the box documentation) about how to configure the Aux switch. Basically there are some jumpers on the PCB in the front panel. Noel

11 years

what has happened to the ML archive?

by tom_a_sparks＠yahoo.com.au

What has happened to the ML archive? tom

11 years

BLIT display debugging advice

by derschjo＠gmail.com

On 10/26/2014 8:09 PM, Josh Dersch wrote: > On 10/25/2014 10:17 PM, Don North wrote: >> On 10/25/2014 8:14 PM, Josh Dersch wrote: >>> I picked up a Teletype DMD 5620 (aka BLIT) terminal a couple of >>> weeks back and I finally got the keyboard working this week; in the >>> meantime a problem with the display has cropped up. >>> >>> See here for a video: >>> http://yahozna.dyndns.org/scratch/blit/WP_20141023_001.mp4 >>> >>> (apologies for the quality and that it's rotated 90 degrees... you >>> get the general idea). >>> >>> For those without video-playback capability, essentially after >>> warming up for awhile (generally after a couple of minutes) the >>> screen starts shaking horizontally; like the horizontal position is >>> oscillating rapidly. This causes "fringes" on the horizontal edges >>> of the picture, as this oscillation occurs multiple times during the >>> course of a single rescan. Generally it gets worse and worse the >>> longer it's been on, though sometimes it will stabilize for a little >>> while. >>> >>> I thought it might be a bad solder joint and I started prodding >>> around with a dowel when the set was "cold" but I was unable to make >>> the screen jump at all while doing so. I also cleaned the >>> horizontal position and horizontal oscillator pots with some contact >>> cleaner to no real effect. >>> >>> I am not particularly good with CRTs, working on them is not my >>> favorite thing, something about the high voltages I guess :). Anyone >>> have any suggestions? >>> >>> Thanks, >>> Josh >>> >> >> It appears the the screen is jumping in some integral number of >> pixels horizontally, like 32 or 64. I don't see any vertical scan >> line displacement. >> >> I would check that the digital horizontal sync (and blanking if >> available) are rock solid, and that the digital pixel stream is gives >> a stable eye, and >> it solidly locked to the horizontal sync signal. >> >> Based on the short little movie I would suspect more of a digital >> issue than a monitor analog issue, at least for starters. >> >> Don >> >> > > Thanks (to both you and JWS) for the tips. I'll see if I can get a > scope hooked up to the sync signals sometime this week, though the way > the behavior progresses (it gets steadily worse and the amplitude of > the oscillations gets greater) makes me think it's probably not a > problem with the signal coming from the display logic -- a digital > failure I'd expect to stay approximately the same, something that > increases in magnitude over time seems more like an analog thing, but > maybe I'm jumping to conclusions :). > > At any rate, it doesn't appear to be a thermal issue -- I powered it > on this afternoon and it's now immediately showing the issue, much > worse than before; to the extent that I can hear a not-very-pleasant > whining from the flyback that makes me nervous to run it for any > significant length of time as I'm afraid something (like the flyback) > might get damaged. > > I may attempt a recap at some point (when I find time -- I don't know > why I keep getting into new projects when I have no time for them...) > since it's likely due anyway. There are a lot of capacitors to > enumerate and stuffed into a relatively tight space. Did I mention > that I hate working on CRTs? :) > > Thanks again, > - Josh > > Just a a quick follow-up here: I recapped the BLIT this weekend. Recapping the monitor's power supply had no effect but after doing the main PCB it seems to be humming along nicely. I also redid the logic power supply while I was at it. Now to fix the mouse... - Josh

11 years

FS: Apple 20SC Hard Disk, Tape Backup 40SC and Apple CDSC- Zero Footprint Drives for Plus/SE

by slandon110＠gmail.com

More stuff cleaning out from the move Got the following in working condition. These are all zero footprint and fit under the Compact mac machines. Also stacks nicely next to the Mac II Series Apple 20SC External SCSI Hard Drive- Commonly used with the Mac Plus and SE Apple Tape Backup 40SC- Tape Backup drive Uses QIC Tape Apple CDSC Single Speed CD-ROM Drive

11 years

MCT Serial board mystery - Can you crack the pinout code?

by drlegendre＠gmail.com

Decided to take a good shot at putting my only S-100 serial board to use. Figured the place to start was ID'ing the connector pin-outs so I could set up a cable and begin the process. Lacking any docs whatsoever, all I could do was trace out the PCB and try to ascertain what was what. So here's what I've come up with - can +you+ figure out which pin is which? Board has two outputs, J1 & J2. They are standard 10-pin DIP headers, using the standard numbering scheme. We'll look at J1; J2 is essentially the same, but routes to different pins / chips / transistors. Pin 1 - Col. of 2N3906 (Base is driven by opt. 2 of 1458 - see Pin 7) Pin 2 - Pin 28 (DB3) of both 1014 & 1015 UARTs Pin 3 - 1K pull-up to Vcc (12V? Same Vcc as 1458s) Pin 4 - 150R -> 47R -> Pin 6 w/ XNOR input 1A at 150/47 junction Pin 5 - n/c Pin 6 - 47R -> 150R -> Pin 4 w/ XNOR input 1A at 150/47 junction Pin 7 - 1K2 -> opt. 2 of 1458 (see Pin 1) Pin 8 - GND Pin 9 - 1458 opt. 1 Pin 10 - GND So we have what looks like three (3) each Inputs & Outputs, plus a Vcc and GNDs: Inputs - Pin 2, 4, 6 Outputs - Pin 1, 7, 9 Vcc - Pin 3 Gnd - Pin 8, 10 So.. what do +you+ make of it? =)

11 years

FS: Commodore 64 Items. ZoomFloppy, User Port Relay Cart and Comet64

by slandon110＠gmail.com

Just clearing out more stuff, got the following commodore 64 items that need a home Jim Brain's ZoomFloppy- Allows you to connect your 1541 to your PC to make Floppy Disks- Works Great. First $20 shipped takes it Comet64 Internet Modem- Serial to Ethernet Adapter for your C64, Also allows you to use Virtual Disks over the internet. First $25 shipped takes it. User Port Relay Cartridge Essentially a GPIO Cart for the C64, you can turn relays on and off through basic $20 shipped Takes it

11 years

Just Moved: Clearing out sale

by slandon110＠gmail.com

I just moved into a new place, and after moving the amount of computer stuff I have, Ive decided that I need to thin the collection. I have the following Nice original Mac 128k with carry bag, manuals, original ssw disks, boxed external 1200 modem, external floppy disk drive And Imagewriter I- Everything is there except the box, Has boxed Mac Software with it too, MacTerminal, Mac Pascal. MacPaint/MacWrite. Even the original audio cassette tour tape. Mac 512k- Has Aldus Asset Tag on it #201- Former Pagemaker Dev machine, with external hard to find Hard Disk 20, the one that connects to the floppy port. Macintosh Plus- Works but needs a keyboard & Mouse Macintosh Classic- Works but needs a cap job. Make a fair offer on anything. It needs to go

11 years

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test-drb November 2014