test-drb January 2015

test-drb@ccmp.vtda.org

175 participants
253 discussions

by jnc＠mercury.lcs.mit.edu

> From: Jay West > The "two 11/73 machines" deal has been claimed. Just out of interest, what kind of disks did the machines have? Noel

11 years, 1 month

MEM11 Status Update

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > It is the generic bulb panel they used for all of the 8/11/15 panels on > the top of the racks. I think for the -10, too (and that was possibly the initial use, given the 36 wide lamp array - or, at least, they had the -10 usage in mind when they did it). I looked at my DECsystem-10 manual, and I suspect that at least the DF10 (channel), RP10 and TM10 controllers used it (4 rows of 36 lights, in the same aspect ratio), and maybe some of the memory cabinets (MB10, MD10) too - they have the right size, etc but have 4 switches in the lower left corner. Noel

11 years, 1 month

equipment available

by jwest＠classiccmp.org

I received the offer below, contact me off-list if interested. J I have two MicroPDP 11/73 computers I would like to sell. Last time I checked (5 years ago) they were working just fine. They have hard drives, no tape drives and were running DCL. I have no manuals and no console terminal. They are very heavy, so shipping is not an option. I am located in Eastern Pennsylvania, between Allentown and Philadelphia.

11 years, 1 month

MEM11 Status Update

by jnc＠mercury.lcs.mit.edu

> From: Guy Sotomayor > I'm building a "LED" board that attaches to the MEM11. ... I couldn't > resist more blinkin lights. Oh frabjous day! Das blinken-litz!! Excellent!!! Now I'm _really_ going to want a stack of these... :-) > The LED board will display all of the indicators for the RF11 > controller in a layout similar to what was on a real RF11. ... > It's optional and will connect to the MEM11 with a small cable (I plan > on using RS485 drivers for the cable) so the LED board can be a fair > distance away. Hmm. Looking at the original RF11 display panel, some of it may be impossible to really emulate; e.g. it displays the contents of the shift register used to assemble words from the bit stream being read from the disk; it's probably not feasible to emulate that... And of course, many of the error bits only make sense with an actual disk (e.g. the various Timing Track errors). How much bandwidth will you have from the board to the display panel anyway? I assume there will be latches on the display panel, and one sends commands down the link to turn given latches on/off? Looking at the original display panel, although it had the extended memory bits, it didn't show the memory address (it does have the disk address). Maybe we could put that where the shift register display used to be? (And speaking of the original display, I couldn't find a picture of one - does someone have one, or, better yet, an actual RF11, so as to copy the look of it as closely as possible?) > (I haven't looked at doing an overlay to make it look pretty) Oh, yes, please do!!! > it'll be somewhat generic (4 rows of 36 LEDs). I counted up (no doubt you did the same :-), and on the longest row (at the top), there are 30 lights, plus 4 empty spaces for the gaps between blocks, so 36 is good. Will you be grouping them in 3's, with slightly larger gaps between each group of 3? That would really maximize the ability to look just like the old RF11 display panel. And warm white LED's, please (of course :-). I'm really going to have to get going on my UNIBUS PDP-11's. I've mostly been working on the QBUS ones, but if I can have blinking lights... :-) I'm already planning on how I can put /, /bin and the pipe device on separate RF platters, so I can watch the lights and see what the machine is up to.. :-) Noel

11 years, 1 month

MEM11 Status Update

by jnc＠mercury.lcs.mit.edu

> From: Guy Sotomayor > the way that it works is that 144 bits will be shifted out and then > all latched at once. Ah. That will limit the rate at which you can update the lights, though, right? I mean, you won't (be able to) update the panel after every word, will you? Although I suppose even if you only do it after each transfer, that's probably still going to give much the same visual effect. > Will you be grouping them in 3's, with slightly larger gaps between > each group of 3? That would really maximize the ability to look just > like the old RF11 display panel. > No, it'll be just like the DEC panels. All of the LEDs (in this case) > will be evenly spaced. The overlay masked the bulbs that weren't used. Ah, I was faked out by the illustration (not a picture, alas!) in the RF11 manual, it looked like they were grouped. I wasn't sure if the larger spaces between various fields were just bulbs they didn't wire up, or if they were also masked by the overlay; I just looked at some of my KA-11 overlays (now _there's_ a machine with blinking lights! :-), and they are indeed blanked in the overlay, so I would guess/asssume they did the same on the RF11. > From: Bob Rosenbloom > I have an indicator panel that's labeled "Peripheral Indicator Panel > 5406458A" > No overlays or anything to indicate what it was used for. Is it > possibly the disk indicator panel? That sure looks like it. Too bad you don't have the overlay... Now that I think about it, I wonder if that panel was originally used on the KA? The 36 bits are certainly suggestive... I'll have to see if I can find a picture of the disk/tape controller display panel from the KA and see if that could have been it. Noel

11 years, 1 month

Building an 8008 SBC with modern components

by computerdoc＠sc.rr.com

Hi Guys, Has anyone ever built an 8008 SBC using modern components like CPLDs and/or FPGAs in place of the ancient hard to get parts used in the first 8008 based microcomputer? I'm looking at trying to do it on a small PCB, but obviously not sure of the exact size yet. Any ideas, thoughts anyone? Kip Koon <mailto:computerdoc at sc.rr.com> computerdoc at sc.rr.com <http://www.cocopedia.com/wiki/index.php/Kip_Koon> http://www.cocopedia.com/wiki/index.php/Kip_Koon

11 years, 1 month

Weekly Classic Computer Trivia Question (20150121)

by dpi＠dustyoldcomputers.com

Many of us on this list are collectors of one sort of computer or another. I don't think of myself as a collector so much as a caretaker of my PDP-8. Of the things it has been fairly easy to get in recent years are the CPU and its related cards for the models that were produced in fairly large numbers. What is not easy to get are peripherals for these machines. So here is a question relating to the Type 750 high speed paper tape reader found on the early models. A few years back we were working on getting the CPU back in good working order. We needed to read in the diagnostic paper tapes but the reader was not reliable. Went through the tuning procedure and found that it was trying to read the tape at nearly 450 cps. After tuning it up the full speed now sits at 342 cps. The question is how many frames does it have to read before it reaches full speed? A) 1 B) 10 C) 50 D) 100 This is probably a somewhat squishy number and would depend somewhat on tuning. I wrote a couple of programs to determine this so I could add correct delays to my emulator. I was able to obtain a 3 microsecond resolution count of the delay. How that was accomplished might make for another trivia question.

11 years, 1 month

Sugru (moldable rubber) for ???

by j＠ckrubin.us

This seems like some pretty cool stuff that might be useful in restoration work. Has anyone tried it? http://sugru.com/about

11 years, 1 month

Releasing Cover Off of Nashua RL02 Pack?

by leec2124＠gmail.com

I have a couple of Nashua brand third-party RL02 packs I'd like to remove the cover from, shown here: https://plus.google.com/photos/104239531634140817575/albums/610685195575310… The DEC RL02 packs have a slider release on the handle that one can use to remove the bottom cover before inserting the pack in the RL02 drive. However, the Nashua packs are missing this mechanism, and just lifting the handle does not release the bottom cover. Any hints on how to release the bottom cover off these packs? Thanks! Lee Courtney

11 years, 1 month

Maxtor XT-2190

by tshoppa＠wmata.com

Al writes: > On 1/19/15 10:43 AM, Tom Gardner wrote: >> FWIW, microstepping goes back to at least the CDC SMD of the mid-70s >> and even some stepper motor drives were microstepped. So there is no >> question the XT2190 can do it. > Obviously, though with the limited documentation it would take some reverse engineering of the Maxtor servo system to do it. There is no way provided to do it from the 34 pin edge connector that I can see. My belief (perhaps unfounded) always was that when a XT2190 begins emitting "squeals and beeps" it is because the MFM interface has asserted "recovery mode" and it is microstepping. Oh, 20 years I was abandoning XT2190's whenever I could! I dreaded walking into the lab to find the RD54's emitting squeaks and beeps indicating problems reading them. Are the squeals and beeps from the head positioner, or is there a separate piezo element for those? It was really loud and obvious and would not be surprised if there was a piezo beeper just for making them. Then again firmware in the drive may have known how to make the head positioner squeal too. Perhaps the squeals and beeps were not recovery mode but simply re-calibrating on track zero.

11 years, 1 month

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test-drb January 2015