test-drb October 1999

test-drb@ccmp.vtda.org

216 participants
748 discussions

Media interchange sillinesss (Was: floppy controller IC (wasRe:

by Glenatacme＠aol.com

In a message dated 9/30/99 8:36:50 PM EST, cisin(a)xenosoft.com writes: << Nevertheless, YMMV! >> YMMV? << Although I've had a moderate amount of experience of it NEVER working reliably, some folk seem to have a knack for using the wrong coercivity media and having it work just fine. Hmmm. >> Perhaps it's my own personal magnetism ;>) Glen Goodwin 0/0

24 years, 7 months

RCA 1861, NTSC and a DEC VR-201

by pete＠dunnington.u-net.com

On Oct 1, 1:28, Tony Duell wrote: > Indeed (although occassionally you get a board where almost every > resistor is one of the strange E96 values for not really good reason). And surprisingly often in an RC circuit where the capacitor is +/-20% tolerance :-( > I am also convinced that a lot of transistors are chosen because that's > what the designer happened to have in stock :-). Yes there are critical > ones, but I could tell you some good stories about substituting all sorts > of transistors with 2N3904s and 2N3906s and still having the device work > _perfectly_. There are other transistors besides 2N3904s and 2N3906s? You mean BC109/184s, right? :-) -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 7 months

PDP-11/44 (configuration and identification)

by west＠tseinc.com

Closer examination of my newly acquired 11/44 shows the following cards (right to left, as when standing at the front panel looking back towards the power supply).... CIM/M7090 open slot open slot DATAPATH/M7094 CONTROL/M7095 MFM/M7096 CACHE/M7097 UBI/M7098 open slot Standard Memories MM-144 open slot open slot open slot M9202 side 1 M9202 side 2 way down towards the front is a G727A Grant Continuity (about 2"x2") open slot open slot open slot open slot open slot open slot M9302 Most of these cards intuitively make sense as to their function. But what is MFM and UBI? The standard memories MM-144 looks like half the sockets are populated - I'm thinking 512K? Is this a runnable system or do I have to add cards or move cards to get a boot console alive? The system id tag says 11/44-XX upgraded to 11/44-CA. What's the CA designation? There were 3 cables screwed to a metal bar just thrown inside the cpu chassis: One was a Berg14 to Berg24, BC44D-09. Wheres this go from/to? One was Berg24-DB25F, BC44A-10. I'm guessing system console :) One was 20 pin DIP ribbon to berg20, and the berg 20 plugged into a little adapter that presented DB25. Any ideas? Lastly, the front panel switch. Appears 3 position, set left, set center, and momentary right returning to center. Is this correct operation or is the switch messed up? Anyone have a spare TU58? <Grin>! Just curious about most of this, don't really have time yet to work on it (still slaving over HP2100's and 7900A and 7906)! Jay West

24 years, 7 months

color video terminals for twinaxial

by rhblake＠bigfoot.com

Anyone know of a really good reseller of used/operational color VDT's that work on twinax line? We're getting a lot of them dying at work (IO's and Decision Data brand) and they aren't worth the $150 an hour they want to repair them. Any info is appreciated. I'm in the central US so the closer the better.

24 years, 7 months

No subject

by sescom＠sescom.com

I would like to buy a manual for a TEK 5l4N. Please respond to Franklin J Miller, SESCOM inc. 702-565-3400 or email sescom(a)sescom.com

24 years, 7 months

New addition to the collection....PDP-11

by CLASSICCMP＠trailing-edge.com

>A PDP-11/44. It would appear that inside the cpu chassis is a CIM? card, >about 5 cards that make up the cpu, and a memory card. There also looks to >be two other cards, one I'm guessing just joins the backplane sections >together, and the last looks like a bus terminator of some type. Do I have >enough to test and start playing with? I've never seen a Unibus machine, but >I'm guessing the CIM is for hooking up a console and getting some type of >boot processor program visible? Indeed, you do plug the console terminal into the connector labeled "Console terminal" on the CIM :-). The other 5 cards you should have are the M7094, M7095, M7096, M7097, and M7098. If you turn on the 11/44 without backplane continuity, you'll likely get a "CP didn't start". With all those empty slots, you don't have backplane continuity! -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

24 years, 7 months

HELP! DHV-11 switch settings...

by CLASSICCMP＠trailing-edge.com

>I need to set a DHV-11 to CSR 160440 and I don't have the docs, is the dip >switch dedicated to the CSR or are some of the bits not included? I need >this for the VCF tomorrow! There are two 8-switch packs: 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 O O O O C O O C O O O C C O O O \---/ \---/ \------/ \---/ \---/ 6 0 4 4 3 0 \------------------------/ \---------/ | \ Sets the CSR to 160440 Sets the Vector (low digit is always 0, high to 300 (low digit always 0) digits are 16 or 17) -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

24 years, 7 months

HELP! DHV-11 switch settings...

by cmcmanis＠freegate.com

I need to set a DHV-11 to CSR 160440 and I don't have the docs, is the dip switch dedicated to the CSR or are some of the bits not included? I need this for the VCF tomorrow! --Chuck

24 years, 7 months

Media interchange sillinesss (Was: floppy controller IC (was Re:

by edick＠idcomm.com

Well. . . it wouldn't have made much sense for the folks who made media to admit that they were merely charging more for the media marked "double-sided" when they were alike in every other way. It seemed that the only real difference in many cases was that some diskettes simply were priced higher. The old 8" drives required you punch holes in the appropriate places and cover the old ones if you used "single-sided" media in a 2-sided drive, having punched the hole, which was the only difference. Since they were available, this swapping of media from one application to another happened all the time where I did much of my work back in the mid-80's, and I'm not referring to merely a few dozen of each drive type, as we were testing and qualifying drives by the thousands. That was pretty boring work and, seeing lots of different media, it became obvious when there really wasn't a difference other than the label. Dick -----Original Message----- From: Chuck McManis <cmcmanis(a)mcmanis.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Thursday, September 30, 1999 11:55 AM Subject: Re: Media interchange sillinesss (Was: floppy controller IC (was Re: >Fascinating stuff, the old "HD/DD/SD" debate rages even today. Fortunately >half of the conversation gets filtered on this end. > >Fred's absolutely correct. > >I can add only one Factoid that was true in 1986 which was that Sony and >Verbatim had both admitted that they were only made double sided diskette >media and the single sided disks were in fact double sided capable. But >_nobody_ ever claimed they used a single emulsion for both HD and DD disks. >For formats where the emulsion was the same for SD vs DD disks they did use >the same media. > >--Chuck

24 years, 7 months

Freguson Big Board and Big Board II

by edick＠idcomm.com

Have any of you guys got definitive and detailed information about these early 1980's single-board computers? I've got a pile of them with very little doc and none on the BB-II. I'd like to determine whether any or all of these babies work before I offer to give away stuff that's totally useless because it's broken. Several of these have been hacked extensively and I'd like to restore them to their minimal but functional configuration. Further, the BB-II has a SASI interface which would, if it worked, help me to sift through a pile of SASI bridge controllers. All in all, that would be a REALLY big help. I also have come onto rumors that there are published hacks to the BB-I which bring it up to speeds comparable with the -II version. Any help with that would be appreciated as well. thanx in advance, Dick

24 years, 7 months

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test-drb October 1999