test-drb April 1999

test-drb@ccmp.vtda.org

170 participants
1190 discussions

Real Hackers, tools of the trade (was Re: Vector Graphic range...)

by CLASSICCMP＠trailing-edge.com

>> > Real hackers carry a Leatherman if 'there just might be something >> > interesting' and a 99MP kit + LogicDart if they know there are machines >> > up for grabs :-). >> >> I guess I'm not a real hacker yet, since I don't even know what a 99MP kit >> is. But I do carry the other items. >It's that red tool roll from Xcellite that DEC field servoids also carry. >It contains Phillips, flatblade, Allen hex, nutdrivers and Bristol spline >drivers. I added Pozidriv blades to mine (essential if working on >European machines). I understand the attraction of those Xcellite sets, especially for field service work where the total weight is a major concern. But they're among the worst "feeling" screwdrivers I've ever used; no matter how I hold them they feel like cheap pieces of junk, and they're always just the wrong size for my hands. Tim.

25 years, 3 months

Rebirth of IMSAI

by allisonp＠world.std.com

<I'm just about to consider firing up one of my old CP/M S-100 boxes just fo <spite and to see if I can get it to run the way I want. It starts with <wanting the CPU board, and I'll probably have to try several, to run the 8 <MHz Z-80H I still have lying about somewhere. Then I want to run the 8" I say go for it. FYI, Murph the NS* horizon turned 21 this year. It's NS* box, and cpu(@ 8mhz), compupro ram, my 765 based floppy and a Teltek MFM controller. I also have a compupro with 512k of static runnign at 6mhz. the killer system however is using a 84c050 z80/10mhz, MMU with 512k static ram (no waits) smart floppy and smart HDC. The floppy and hdc system are 8085 powered and have their own DMA (Ieee696 TMA) interfaces. I started that system back in 81 and for years it was the PC killer. Allison

25 years, 3 months

DECtapeII drives available - contact the person in the post, not me

by mbg＠world.std.com

>Xref: world alt.sys.pdp11:6181 >Path: world!newsswitch.lcs.mit.edu!newsfeed.enteract.com!news.he.net!remarQ73!supernews.com!remarQ.com!remarQ69!news.remarQ.com!not-for-mail >From: "William B. (Bill, Mr. Bill, etc.) Benshoof, II" <mrbill(a)edge.net> >Newsgroups: alt.sys.pdp11 >Subject: DECTAPE II Available >Date: Thu, 01 Apr 1999 08:14:49 -0600 >Organization: M. R. Ducks Productions >Lines: 11 >Message-ID: <37037F59.38E2(a)edge.net> >Reply-To: mrbill(a)edge.net >NNTP-Posting-Host: 209.215.156.33 >NNTP-Posting-Date: Thu, 01 Apr 1999 14:09:59 GMT >X-Trace: 922975799.179.17 MPP1WEAUI9C21D1D7C usenet1.supernews.com >X-Complaints-To: newsabuse(a)remarQ.com >X-Mailer: Mozilla 3.01 (Win95; I) >MIME-Version: 1.0 >Content-Type: text/plain; charset=us-ascii >Content-Transfer-Encoding: 7bit Y'all, I have 8 DECTAPE II tape drives (guts only, no case) available. Anyone Interested? I'm not a regular subscriber, so E-mail me at mrbill(a)edge.net. Peace, Bill Benshoof

25 years, 3 months

Vector Graphic range...

by fauradon＠pclink.com

Nope, most of the time I know what's inside ;-)... This was a rare occasion where I got two of them plus a set of external drives, one with two 5 1/4 the other with a hard drive and a 5 1/4, a humongous daisywheel printer and a complete set of software and documentation for $20. "Do you look at the teeth of a free (or almost) horse?" I just got sidetracked in figuring out what the beast was. I'll have to check it out now. Francois >Don't you guys open your boxes to see what's inside them when you first >get them? > >Sellam Alternate e-mail: dastar(a)siconic.com >--------------------------------------------------------------------------- --- >Don't rub the lamp if you don't want the genie to come out. > > Coming in 1999: Vintage Computer Festival 3.0 > See http://www.vintage.org/vcf for details! > [Last web site update: 02/15/99] >

25 years, 3 months

Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

YES! Finally, a point of agreement! One of the S-100 boards I'm looking to place has a component suspended in space above the board, and, in fact floating aboug an inch above one of the regulators. This was undoubtedly built by one of the self-styled experts I had working on automation software back in the early '80's. These guys had me buy all kinds of stuff we ended up not using and they excused the occasional waste by saying they bought a kit in order to save money. Of course they didn't consider that the cost of building it was a cost to me as well. I rather suspect that, in spite of the strange insertion of this floating component, the board worked. On the other hand, I had an expert prototype a low-current highly noise-immune PLL, for use in data/clock separation in hard disk drive interfaces, which was constructed as you describe, with a piece of copper-clad, double-sided, with the upper layer at Vcc and the lower at Vss. It had wires tacked to other wires and suspended inches above the board, while the components were soldered to pads cut from the solid plane, with machined pins soldered through the board and the IC's plugged in belly-up and wires soldered to their pins. It looked pretty tentative, but worked very well. It extracted clock with lock in about 5-6 microseconds all the time! My target was 10 microseconds. What's more, it required only a single supply. Tentative though it was, it had an order to it that you don't easily overlook. About the simulators . . . I've found that fewer and fewer of my clients blindly, and it is blind, believe me, accept a "rock solid" prototype, until after a simulation reveals that it not only does work, but, rationally, should work. The simulator rules out easily overlooked synergies between miscalculations. These are immediately revealed in a simulator when you run sensitivity analyses and worst-case analyses. If the circuit is misdesigned, it often works well at one of the extremes, but doesn't work at nominal spec. Dick -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, April 01, 1999 2:32 PM Subject: Re: Kits vs ready-made (was RE: Rebirth of IMSAI) >> >> senior engineers. The excuse was that "it's not a deliverable," but >> often >> >> the shoddy technique (air-wires, etc) made for problems which couldn't >> > >> >If that's another name for dead-bugging, there's nothing wrong with it if >> >used correctly. In fact IMHO it's the _only_ way to prototype >> >high-frequency circuits with any sort of reliability >> >> >> I have used dead-bug patches quite a few times myself. More specifically, >> dead-bugging is typically gluing or taping an IC onto another's back and >> running wires between it and the appropriate points in the circuit. I don't >> mean that, so much, but using multiple feet of #40 magnet wire with the >> shellac sanded or scraped off and having the scabbed-in IC floating on a web >> of wires 3" above the board . . . ??? > >Oh well, now that I would object to, even on a prototype. When I >dead-bug, all the large compoents (chips, etc) are fixed to the >groundplane (often a piece of copper-clad board). And the ground >connections are made with short pieces of 22swg-ish wire, soldered firmly >(they'd normally support the components even if they weren't stuck down). > >Of course, one other thing is that my circuits have generally been >intended to be used by myself, or perhaps somebody else who can read a >schematic only. I don't give them to unsuspecting 'customers' in that >state. Even so, my prototypes are solidly constructed. > >> >> >And if you trust simulations to correclty predict the behaviour of even >> >simple circuits, well, have I got some storys to tell you... >> > >> Yes, I have a few, too, but . . . Careful now . . . I've spend thousands of >> hours in front of a big tube waiting for a simulation. I am a big believer, >> and believe further, that anyone who claims that simulators don't have a >> place, as some old-timers do, just hasn't investigated sufficiently. > >This list is based on the principle that a new idea/method isn't necessarily >better than the old method. It might be, of course. And that sums up my views >on simulators. > >Oh, simulations have a place, that much is certain. They are very useful >tools if used correctly. > >What I object to in particular is : > >a) Designers who couldn't prototype the circuit if they tried >b) Designers who trust the simulator implicitly (even if the simulator >has no bugs, which is by no means certain, they might not have given it >all the right information) >c) Circuits that are 'delivered' after only having been tested on a >simulator. IMHO the real test of a circuit is does it work when constructed. >d) Simulators that take longer to provide less information that actually >building the circuit >e) Simulators that can't handle some common occurances (one classic FPGA >simulator can't handle external memory linked to the pins on the FPGA, >for example). >f) Designers who fiddle with the simulation 'until it works' rather than >using good solid design principles. Yes, fiddling with real hardware >'until it works' is equally bad, but I've found that because it's easier >to make changes on the simulator than on real hardware, the use of >simulators encourages that behaviour. >g) Simulators that plain get it wrong. Don't get me started here, suffice >it to say that I've spent too long tracking down glitches in other >peoples designs that the simulator claimed didn't exist. > >In short, in the hands of a good designer, a simulator is another useful >tool to be used alongside all the other tools. In the hands of a bad >designer, it generally leads to disaster. But alas Management often >believe the ads that say that %simulation-program allows anybody to do >design. > >-tony >

25 years, 3 months

ASR-33 Data Format?

by H.Davies＠latrobe.edu.au

At 21:27 29/03/99 -0800, Sellam Ismail wrote: >On Mon, 29 Mar 1999, Bruce Lane wrote: > >> Actually, ASR-33's ran at 110 Baud rather than BPS. > >Same difference. No, Baud and BPS are different. Baud is the number of signalling changes per second. Normally, each signal change gives one bit and then Baud == BPS, but if you encode more than one bit per signal change then they are not the same. This is easily achieved if you have different voltages mean different values. For example, if you use -10V, -5V, 5V and 10V to encode 0, 1, 2 and 3 then the bit rate is twice the baud rate. Huw Davies | e-mail: Huw.Davies(a)latrobe.edu.au Information Technology Services | Phone: +61 3 9479 1550 Fax: +61 3 9479 1999 La Trobe University | "If God had wanted soccer played in the Melbourne Australia 3083 | air, the sky would be painted green"

25 years, 3 months

Classic color video

by bill＠chipware.com

> What were they? I assume one was the termination switch. Well, I'm home now and I realize that I was using a Panasonic TR-120, not my Amdek (I wonder where that's buried?). The only switch that makes a difference is labled: Hi-Z 75 <ohm symbol> It looks good in the "Hi-Z" position although I can now see that if I turn up the brightness and contrast all the way I can just make out the display in the 75ohm position. I've just spent a couple of minutes fooling with the pot shaft sticking out of the back panel and, sure enough, it makes a difference in the behavior of the color regions that the color test program displays. I'll try it on my "good" TV in a little while.

25 years, 3 months

PDP-11/34A rebuild project Was: Re: Post-move diary

by mbg＠world.std.com

>I've got it in the wrong way round several times and it's never done any >damage. It just doesn't work (no display at all IIRC). > >Berg cables in DEC machines are rarely keyed, alas. Actually, I can point to a number of counter-examples of that... Anyway, I'm simply going to keep the cables in the machine in case I want to do it at a later time... I have so many other things to do with the machine to get it running first... >I've found the VT11 prints - sort of. I've got the schematics of the 3 >boards : > >M7013 Display Control >A320 Display Generator >M7104 Bus control + bootstrap They might be useful at some point... but not yet (I haven't even found my VT11 boardset, if I have one). >What I don't have is any information on the backplane. So I don't think >I'll be of much use at the moment. Again, problem is moot until I have more of the required pieces... I'll keep you in mind for the other info though at some point... >I know I don't have the LPS printset. I do have a minimally-configured >LPS somewhere, though. I haven't opened mine up yet to see what I have... if you can easily get to yours, it might help to have info on board order, and UNIBUS connection point... (I take it a terminator has to be in the LPS since it connects to the UNIBUS itself...) BTW - It was pointed out to me that the file containing the picture of my haul was somehow protected... I've taken care of it. Look for a trip writeup with pictures in the near future (I've got it mostly written, I just have to insert the thumbnails and links to the full pictures)... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+

25 years, 3 months

Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

Your commment below about production is true enough, but such arrangements built sloppily will suffer from day-to-day use in an environment where cards are being move about. I'd say one should glue the part down and keep the haywires as short as possible. By the way, in the aerospace industry, 25 pieces is a long run. Almost everything is built in small quantity because you're only building one or two of those rockets or satellites, and by the time you do it again, the design requirements have changed. Dick -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, March 31, 1999 5:40 PM Subject: Re: Kits vs ready-made (was RE: Rebirth of IMSAI) >> >> The classic example is an IC suspended over a PCB by means of the little >> pieces of #40 wire which connect it to the circuit. They're not always a > >Well I'd probably stick the IC down to something, and use thicker wire >(stander wire-wrap wire is quite good for this), but I really don't see >the problem with doing this for experimental/prototype circuits, even >ones that are going to be used. I've done it many times and it's never >given any trouble. > >> terrible way to do things, and they've even been blessed by the analog >> weenies at NatSemi, but their use in modifying or even building circuits >> intended for some practical use is an abomination. Experimentation, well, >> OK, but to use it repeatedly? . . . > >Well, obviously you don't want to use it in production (far too >labour-intensive), but that should be the only problem if it's properly done. > >-tony >

25 years, 3 months

Kits vs ready-made (was RE: Rebirth of IMSAI)

by edick＠idcomm.com

take a look below, please. Dick -----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, March 31, 1999 5:40 PM Subject: Re: Kits vs ready-made (was RE: Rebirth of IMSAI) >> >> Unfortunately, in today's climate ("NOTHING's MY fault!") people buy a kit > >Yes, that attitude is _very_ annoying.... > >> A degree in engineering isn't sufficient qualification, either. Some of the >> crappiest work I ever saw while in the aerospace industry, was by fairly > >Oh, don't get me started on that. I have no engineering qualifications at >all, but, even if I say so myself, I could out-design, out-construct, and >plain out-hack a number of people with degrees in engineering that I met... > >A few classic cases that spring to mind : > >One chap said 'There are no 362.8 Ohm resistors in the box'. I said I >wasn't supprised and asked him what on earth he wanted it for. The >answer : An LED current limiting resistor. That was the value that the >formula had given, so that was obviously the value he needed. > >Another person had problems with a simple RC low-pass filter. And he >certainly had no idea about making sensible approximations. > >The only problem that comes from this is that mangement-droids seem to >think that qualifications imply competence/knowledge. So I'm stuck unable >to get a job :-( > >> senior engineers. The excuse was that "it's not a deliverable," but often >> the shoddy technique (air-wires, etc) made for problems which couldn't > >If that's another name for dead-bugging, there's nothing wrong with it if >used correctly. In fact IMHO it's the _only_ way to prototype >high-frequency circuits with any sort of reliability I have used dead-bug patches quite a few times myself. More specifically, dead-bugging is typically gluing or taping an IC onto another's back and running wires between it and the appropriate points in the circuit. I don't mean that, so much, but using multiple feet of #40 magnet wire with the shellac sanded or scraped off and having the scabbed-in IC floating on a web of wires 3" above the board . . . ??? >And if you trust simulations to correclty predict the behaviour of even >simple circuits, well, have I got some storys to tell you... > Yes, I have a few, too, but . . . Careful now . . . I've spend thousands of hours in front of a big tube waiting for a simulation. I am a big believer, and believe further, that anyone who claims that simulators don't have a place, as some old-timers do, just hasn't investigated sufficiently. > >-tony >

25 years, 3 months

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test-drb April 1999