test-drb November 1999

test-drb@ccmp.vtda.org

211 participants
749 discussions

Just found schematics to a Tube Mini! 1958! WOW!

by dylanb＠sympatico.ca

This unit is not listed anywhere on the web and have not found it in the list of Digital Computers (though I can't find the page I usually look at). In going through my PDP-8 stuff I found a book called "RCL". This *mini* was built in 1958. I uses delay line memory, has a number of mini-computer functions (many tube flip flops) and it's programmed with wires (i think). It has a bulb front panel with some program control switches. Interfaced to it was a printer and a CRT (maybe more, I am just getting through the memory control schematics). Its memory control system contains: Set address, decimal decoder, subtract 1, read , add, write (all these three have many other function control flip flops), address overflow, decode, print, carry, add+1, end storage... Address system is 8 bit. (256 bits of address space) OOOOOOOOOOOOOO.. (just flipped the page) it *does* have a core memory array. (5 stages X 256 bit) OOOOOOOOOOOOoo (just flipped the page again)... It has a 16 bit A/D converter (tubes) (sorry but OOOOOOOOOO - just flipped the,,,,,....) it has a data register .. Ahhh, this is a 16 bit mini, with core (just found more core memory) Getting an instruction set here - (so far): Add +1 Add Add -1 (subtract) Compliment Add with carry reset (jump?) stop next page - A/D unit (yikes!) many tubes..... CRT display (uses delay line memory ... I think.. if not , no idea yet) Power supply is nasty printer control modules - yuck! Okay, indicator panel (found it) has: 16 bit data bus, 8 bit address bus (light bulbs) Programming - weird, user has access to core memory, has "START, RESET switches), it has a *really weird* tube for "real time".. looks to be a cesium tube or delay tube... many sensors for "real time" more programming instructions: print clear to zero display I thought at first this unit was a counter but I see a whole programming area with different op codes, two types of storage and a printer with CRT. This should qualify as a *kind* of mini... It was meant to work with A/D and D/A with some coded instructions in core memory/wires. Anyone hear of such a unit? Part of it is called "multichannel analyzer" but that is only the a/d subsystem. I only have the schematics so I have to figure stuff out from there. john

25 years

Debugging ONMIBUS cards

by ethan_dicks＠yahoo.com

--- allisonp(a)world.std.com wrote: > No I don't. First off make sure the "tty" is configured correctly. Real > TTYs are wired with keyboard bit 7 high and all 8 reader bits active. > This is hard to duplicate with terminal programs. For now, I'm using a VT220 as an output-only device. I haven't gotten as far as attempting input. > > I'd still love to hear why a KK8A isn't happy with the -8/e frontpanel... > > They are not compatable at the control level not the bus level. The KK8a > was not designed with a "peripheral" reaching into it's registers and data > paths. I'd bet if the kk8a runs in the 8e box the FP can display but only > limited things. That sounds like a reasonable explaination, but how, then, does the DKC8AA "reach into" the KK8A to implement _its_ frontpanel? I would have thought that the OMNIBUS is the OMNIBUS is the OMNIBUS. Thanks, -ethan ===== Infinet has been sold. The domain is going away in February. Please send all replies to erd(a)iname.com __________________________________________________ Do You Yahoo!? Thousands of Stores. Millions of Products. All in one place. Yahoo! Shopping: http://shopping.yahoo.com

25 years

Floppy Drive specifications

by oajones＠bright.net

Can anyone tell me where I can find Floppy Drive specifications on the internet? Right now I am looking for specs on a Mitsubishi MF504B-318U 5 1/4" drive. I forget if this drive is DD or HD. I have some other drives I need to get the specs on too. Thanks in advance... --Alan

25 years

Oscilloscopes

by allisonp＠world.std.com

<> I agree but I would not recommend someone dropping a couple hundred bucks <> fix an old 20Mhz scope as I am sure they would not limit their use < <It probably wouldn't cost anything like that much... Most older 'scopes <are easy and cheap to repair. I'd agree. generally most scopes are not to bad to fix but some are definately more avoidable like the really old Valved units. <> *exclusively* to vintage minis. A 20Mhz scope in RF/High speed logic <> troubleshooting/design is totally useless. A 20Mhz scope isn't even very < <_Nonsense_. I've done a heck of a lot of troubleshooting on quite modern <stuff using that 15MHz 'scope I mentioned earlier. It all depends on how <you use your instrument and if you know how to interpret the results. I agree. At the time the PDP-8 was common the 465 was the hotshot on the block and few had one. I remember seeing 316s with the dual trace plug in used for that! <Maybe not Tektronix, but there are still 20 and 30 MHz 'scopes in the <catalogues. And most of them are horrible -- they don't trigger properly, the B&K, Hitachi and Leader are three I know well and they trigger OK, say about as well as most of the HPs. ;) Seriously, they arent Tek, they don't have that nice trigger but many others that are faster don't. Most of the better 20mhz scopes really do see 20 and then some and a few of the off brand faster ones don't. Tek is expensive, DSOs/DPOs are not always interchangable either. All of this is mostly unimportant to troubleshooting a errent core stack. <etc. You'd be _much_ better off spending the money to fix up an old <Tektronix than buying one of those. Of course if you can afford a new Tek <with all the bells and whistles, well that's great!. If you can fix one, some of them can be had for a song. a few are really collectable on their own merits. I'd really like to have a 316! <At least one company seems to define an 'x MHz scope' as : If you turn <the Y gain right up and apply the maximum allowed signal then you'll see <_something_ at 'x MHz'. I am not joking... Some are pretty poor. The NLS MS15 is in that pool. However being battery operated and a 75$ investment back in 76 made it a fair little scope even now. OH, that core... there is a switch on the g111 module and if misset the core will not work. It sets the slice time for the read amps. If wrong the code has stuck bits or worse flakey ones. The other thing that can go off is the current drivers, if the current level is off... no write, no read. Allison

25 years

Oscilloscopes

by edick＠idcomm.com

Going too cheap on a 'scope might be regretted. Buying too recent a low-end instrument might be a disappointment as well. A 20-year-old 465 in really decent functional condition and with al its parts and manuals can be had nearly any day from a retailer of such hardware for $400, including a pair of 100 MHz probes with most of their accessories, and often for less than that. It (including the somewhat less well-suited 'B' version) will do ANYTHING you need on most classic hardware. Knowing that, by itself, is worth quite a bit, because you KNOW when you power it up, it will do what you need. What might be even more interesting is the more or less equivalent TEK 466, which is a storage scope. That will let you do even more than the 465 and, when you can find one, won't cost much more. A current-generation low-end analog 'scope will not begin to do what a 20-25-year-old one will do, because 25 years ago, the 20 MHz scope was the typical workhorse. If you look at today's, it's a toy. If you find a used TEK 935 (?) which was considered a "student" instrument for use in schools, etc, it's all solid-state, which means you don't have to use up $5 in power to warm it up, and spend $5 more for a six-pack to drink while you wait, and, though it hasn't got the high bandwidth, it has the delayed timebase, and two channels triggerable either externally or internally, etc. You shouldn't have to pay even $200 for one of these, complete with the two probes, which, by the way, are probably over half the cost. 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: Tuesday, November 23, 1999 7:47 PM Subject: Re: Oscilloscopes >> I agree but I would not recommend someone dropping a couple hundred bucks to >> fix an old 20Mhz scope as I am sure they would not limit their use > >It probably wouldn't cost anything like that much... Most older 'scopes >are easy and cheap to repair. > >> *exclusively* to vintage minis. A 20Mhz scope in RF/High speed logic >> troubleshooting/design is totally useless. A 20Mhz scope isn't even very > >_Nonsense_. I've done a heck of a lot of troubleshooting on quite modern >stuff using that 15MHz 'scope I mentioned earlier. It all depends on how >you use your instrument and if you know how to interpret the results. > >> good at looking at the color burst of a video signal in any detail. Again, I >> find most folks design/troubleshoot in a variety of areas and that's why we >> need scopes with all the toys. I don't see Tek making any more 20Mhz boxes. > >Maybe not Tektronix, but there are still 20 and 30 MHz 'scopes in the >catalogues. And most of them are horrible -- they don't trigger properly, >etc. You'd be _much_ better off spending the money to fix up an old >Tektronix than buying one of those. Of course if you can afford a new Tek >with all the bells and whistles, well that's great!. > >The other thing is that a Tektronix '20 MHz' scope will, in general >display something useful for signals of a considerably higher frequency >(I've 'pushed' a 50MHz 547 (_really old_) to at least 75 MHz). Yes, the >amplitude calibration is off. All signals look like a sine wave. But you >can still make measurements if you have to. > >At least one company seems to define an 'x MHz scope' as : If you turn >the Y gain right up and apply the maximum allowed signal then you'll see >_something_ at 'x MHz'. I am not joking... > >-tony >

25 years

Oscilloscopes

by allisonp＠world.std.com

<> I know the 20mhz B&K would be more than enough to track 8F core problems < <Sure... But if you're buying a 'scope, it makes sense to get one that <will do all that you might need. So while you don't need a 50MHz 'scope <or whatever to sort out 8/f core memory, you might find it worth getting <one for other work. Hence the B&K 20mhz. I do a lot of slow, audio and assorted control stuff that doesn't require a fast scope. My MS15 (bought used 22years ago) is so I have battery operation for portable use. <You don't _need_ expensive test equipment. I've done a lot of fault <tracing using a cheap analogue multimeter and a Radio Shack logic probe. <And with those 2 instruments I managed to extract enough clues to the <fault to replace the fault component first time (most of the time). ;) so happens... <However, I am also sure that there are people here who could use some <more clues as to the fault, who can't interpret every last piece of <information that they can get from simple instruments. And those people <generally make use of rather more instruments, which perhaps aren't <strictly necessary... There in lies the problem. Sometimes the test setup can cause error. Good tools are a must, but good does not always mean the "best" only that is be fully working and calibrated combined with the knowledge to use it. The key is what ever scope is used to know and understand it well, and I mean very well. Generally this applies to many instruments. I happen to do better than average because back when I couldn't afford I had to make do, that meant getting the most and then some. That and over 30 years of experience is particurally handy at times. Oh, the 465 I had, I sold it real cheap to someone I thought could really use a good scope. He dropped it. ;( Allison

25 years

Oscilloscopes

by dylanb＠sympatico.ca

-----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Tuesday, November 23, 1999 9:43 PM Subject: Re: Oscilloscopes >> I agree but I would not recommend someone dropping a couple hundred bucks to >> fix an old 20Mhz scope as I am sure they would not limit their use > >It probably wouldn't cost anything like that much... Most older 'scopes >are easy and cheap to repair. > We are talking about someone here who is *unable* to fix his own scope. I am sure you or I could fix it for under $5 (providing the CRT and flyback are good)... but in the real world most people *can't* fix their own test equipment. In fact, most general repair shops aren't able to do a fair job.... >> *exclusively* to vintage minis. A 20Mhz scope in RF/High speed logic >> troubleshooting/design is totally useless. A 20Mhz scope isn't even very > >_Nonsense_. I've done a heck of a lot of troubleshooting on quite modern >stuff using that 15MHz 'scope I mentioned earlier. It all depends on how >you use your instrument and if you know how to interpret the results. Tony, I can't see distortion in an oscillator at 61.25Mhz with a 20Mhz scope.... And I have pioneered *alot* of code cracking on video signals and that would not be possible with any old equipment. You *can* do alot of troubleshooting with a 15Mhz scope... but, for instance, I can't see distortion/FSK data on a122.7Mhz oscillator/FM transmitter (that band should mean something to you ;-) ) with a 15Mhz scope. Each to his own... You obviously love working with old test equipment and support old hardware. I don't see a lot of people out there like yourself anymore.. [although I have met a few non-gui UNIX administrators that hate my guts after tossing their servers for NT] .. I like working on the old stuff; sometimes even with the old stuff... but I don't bring that into new world work... That's just me. > >> good at looking at the color burst of a video signal in any detail. Again, I >> find most folks design/troubleshoot in a variety of areas and that's why we >> need scopes with all the toys. I don't see Tek making any more 20Mhz boxes. > >Maybe not Tektronix, but there are still 20 and 30 MHz 'scopes in the >catalogues. And most of them are horrible -- they don't trigger properly, >etc. You'd be _much_ better off spending the money to fix up an old >Tektronix than buying one of those. Of course if you can afford a new Tek >with all the bells and whistles, well that's great!. > I agree, but old scopes are expensive to maintain for someone who is not able to repair it himself. >The other thing is that a Tektronix '20 MHz' scope will, in general >display something useful for signals of a considerably higher frequency >(I've 'pushed' a 50MHz 547 (_really old_) to at least 75 MHz). Yes, the >amplitude calibration is off. All signals look like a sine wave. But you >can still make measurements if you have to. MY POINT! I was refering to RF work above... you don't just buy a scope for old mini digital work.. If you buy an old scope/20Mhz you automatically rule out most high frequency analog work and communications. Digital signals look like sine waves.. ever tried to diagnose a problem with an RF circuit with a minimum bandwidth scope??? The waveform looks like pure garbage.. Hence, the need for a *real* scope. > >At least one company seems to define an 'x MHz scope' as : If you turn >the Y gain right up and apply the maximum allowed signal then you'll see >_something_ at 'x MHz'. I am not joking... > Agreed , I have done it with my 2465 (yes, I have had to look at RF higher than 300Mhz)... In fact, I use to use a dual trace Gould (100Mhz) on 200Mhz work..... with minor grief. All depends on the application. Where are you located in the UK? >-tony >

25 years

Convergent technologies workSlate, atari computer lot, etc for sale on ebay

by Maddog1331＠aol.com

Hey all, I hate to solicit bids, but thought you folks might be interested in the stuff I have up for auction on ebay. Here is my seller list: <A HREF="http://cgi3.ebay.com/aw-cgi/eBayISAPI.dll?MfcISAPICommand=ViewListedItem s&userid=maddog1331&include=0&since=-1&sort=2&rows=25">http://cgi3.ebay.com/aw -cgi/eBayISAPI.dll?MfcISAPICommand=ViewListedItems&userid=maddog1331&include=0 &since=-1&sort=2&rows=25</A> I have a bunch of stuff, and have to clear some of it out so I can have some room for a couple of nice systems...the apartment is like full! Thanks for looking, and I have other stuff I will be putting on there soon :-) A bunch of Timex Sinclair stuff, among others. Mark

25 years

BA23 available!

by cmcmanis＠mcmanis.com

I have a BA23 that was "hidden" inside a Sigma Design expando cabinet. (looks kinda like a BA123 except that it has a door on the front, incompatible disk mounting slides and a weird "slave" power supply. I believe the BA23 to be in good working order, I'll pull it out and test it (I know the slave PSU is toast) It is in Sunnyvale CA (94087), I'm willing to part with it for 1.5x shipping however shipping in this case is "take it down to the packing store and have them pack and ship it" since I haven't a box or sufficient packing material to cover it. Because it is in the Sigma cabinet it doesn't have the standard "DEC shelf" for mounting in a rack. It does have a uVAX II badge on it and no drives. Email me if you want it, first come first served... --Chuck

25 years

Spare BA* series chassi?

by ethan_dicks＠yahoo.com

--- "Zane H. Healy" <healyzh(a)aracnet.com> wrote: > Good luck, I won't tell you how long it's taken me to get even a spare BA23 > and BA123 as backups. It took me a long time to find a BA123, too. Cost me a bit of money at the time as well. I've never seen them drop from the skies (but I have picked up $50 MicroVAX I's in the past). > Something to consider with the BA123's is that > they're more than just a computer, they're also a small table.. > ...Mine has a LA75 and a VT420 sitting on top of it, Beware of loading the top too heavily. My BA123 has a dent under one caster because someone probably sat on the corner or did something else unnice to it. I pounded it out as best I can, but that caster is still a couple millimeters higher than the other three. -ethan ===== Infinet has been sold. The domain is going away in February. Please send all replies to erd(a)iname.com __________________________________________________ Do You Yahoo!? Thousands of Stores. Millions of Products. All in one place. Yahoo! Shopping: http://shopping.yahoo.com

25 years

← Newer
1
...
20
21
22
23
24
25
26
...
75
Older →

Jump to page:

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb November 1999