test-drb December 2000

test-drb@ccmp.vtda.org

192 participants
490 discussions

by cmcmanis＠mcmanis.com

Hello Everyone, I had one of those DEC MMJ->DB-25 things come apart on me and expected to see the MMJ connector wired to the DB-25 in the now familiar mode we see in the FAQ, however instead there is an ST 20 pin chip betwixt the MMJ and the DB25! This might explain why they work better than the wired together solution :-) The chip is labeled HTAM1B4 (looks like a house number) then under that is P 9236 (date code I suspect) and then under that "Philippines". Can anyone guess the "real" part number for this chip? no power or passives at all so I presume it runs on phantom power. looking at the PCB I'd guess its wired up as follows: pin 1 - GND 20 - GND 2 - MMJ-5 19 - DB-2 3 - MMJ-2 18 - DB-3 4 - MMJ-6 17 - DB-20 5 - MMJ-1 16 - DB-7 6 - GND 15 - GND 7 - GND 14 - GND 8 - MMJ-4 13 - DB-8 9 - MMJ-3 12 - DB-8 10 - GND 11 - GND The DB25 is a female (DTE?) and while I'm sure of the DB pin numbers the MMJ numbers may be reversed, since I'm never sure if pin 1 on the MMJ is the left pin looking into the connector body or the right pin. (I assume the left pin above) --Chuck

23 years, 3 months

OT (sortof) wanted items (cart & logic analyzer stuff)

by mcguire＠neurotica.com

On December 30, Richard Erlacher wrote: > What kind of equipment to you intend to work on with this new LA? I've used Just general hacking. I'm doing more and more digital stuff (mostly PIC-based) and up 'til now a logic probe, a pulse generator, a DMM, and a fast 'scope have been all I've needed for troubleshooting. I've just been thinking a decent multichannel analyzer might be a nice addition to the bench. > the HP 1630 though it's been about 15 years. It has some nice features. > With today's fairly flexible (I/O) devices, however, you might find it > interesting to build one that uses your PC as a display and acquires the > sample memory contents from the device via the EPP. If you're really > ambitious, perhaps USB would be appealing. It's certainly popular enough. Eh...that would mean getting a PeeCee. Thanks for the suggestion though...it's definitely a cool idea. > If you're determined to buy a logic analyzer, the crux of the task is to > find a unit that's not only fully functional but also fully complete. You > need the documentation ... all of it, and you need the complete set of pods > and whatever mechanism, usually an interface board, that is required to > support it. You'll ultimately be disappointed if it's possible to have more > channels than what you've got, so it's important you have enough channel > boards, pods, and probe clips to support them all. There are usually pod > testers that come with a new logic analyzer, and those often are the first > thing that gets lost. Those are extremely necessary when you're having > trouble gettin a setup to work, because they're the only way you have of > restoring your confidence in the instrument. If there's some sort of method > for storing and processing the sample data, either internally or externally, > you certainly will want that capability. A spare pod is pretty useful, too, > unless you think you will find one, which I, having searched the market > pretty thoroughly at various times, doubt very much. I did find on, > however. Understood. I have pretty good sources for test equipment and docs, so I'll be able to shop around a bit, and try-before-I-buy. > I've had several logic analyzers, and, in '92-93, due to the need for > portability, decided to replace my bench-bound model for a portable, a TEK > 1240, which is the monochrome (cheaper) version of their portable of the > mid-late '80's. I found any number of incomplete LA's. Mostly, the pods > and the sample boards were partly or completely missing. Documentation was > not common, and, though I found some pods for sale, they were not complete, > and none I was offered had documentation. Unfortunately, it's too easy to > develop excessive or erroneous expectations of what the instrument will do > if you don't have doc's so you'd better have them. I found several > 1240/41's for <$250, but those were without pods, several were without the > required sample boards, and none had documentation. I found pods, often > costing more than $250 for a pair, again without documentation and, worse, > without the lead sets and probe clips that you need to attach to a device I've looked at the Tek 1240/1241...both seemed pretty nice. From my sources, though, they get awfully expensive (>$800) if they're complete with lots of options, pods, clips, and docs. > Before you buy, be ceratin that YOUR preferred triggering methods are > supported. I've found triggering the most critical problem of logic > analyzer application, and if there's even a single conceivable mode that > isn't supported, THAT's the one you'll need, ... trust me. Sounds good to me. Thanks for the advice! -Dave McGuire

23 years, 3 months

VT78 - lots of questions

by djg＠drs-esg.com

From: pete(a)dunnington.u-net.com (Pete Turnbull) >That wasn't what I meant. Berg label the connector pins starting from the >opposite end of the connector from the rest of the world, so what I meant >was that on actual connectors, the pins are: > ... Thanks, I have updated the document. I had less trouble building it in the first place than figuring out what I built. The adapter has a normal 3M in it and I had though I got the pin 1 backward on it. Apparently when I built it I knew they were opposite but since forgot.

23 years, 3 months

VT78 - lots of questions

by ajp166＠bellatlantic.net

From: Tony Duell <ard(a)p850ug1.demon.co.uk> >> >Yes, and although the Rainbow has a Z80 in it (which could run 8080 >code), IIRC, the internal VT100 emulator runs on the 8088 processor in >the 'bow. Killer CP/M-80 machine and it also ran CP/M-86 better than most. What was odd is it's one of the rare machines that had DOS with more than 640k! Allison

23 years, 3 months

OT: help...

by ajp166＠bellatlantic.net

From: Tony Duell <ard(a)p850ug1.demon.co.uk> >Over here, virtually all large-ish screen TVs have what's called a SCART >socket. This is a 21 pin connector carrying 2 channels of audio in and >out (4 connections), composite video in and out (the input is also used >for composite sync in in RGB mode), RGB input, blanking, etc, and lots of >grounds. Never seen one here. This set does take composite video in and audio in via jack on front (Sharp). >I've never seen a monitor with a hot chassis. I know the original 110V >version of the TRS80 model 1 monitor was (I have the service manual), and >had an opto-isolated video input, but surely all more recent monitors >have isolating PSUs? Many do, but I was thinking more of TVsets. >About the worst you'll find over here is some varient of the IPSALO >circuit (IPSALO == Integrated Power Supply And Line Output, Line Output >being what we call the horizontal output stage). Comon config here in smaller or lowend sets. >With these, the flyback is on the hot side of the PSU, as is the >horizontal deflection yoke. The horizontal drive signal is opto-isolated, >the horizontal osciallator, vertical deflection, video circuitry, >tuner/IF strip, etc are all isolated from the power line, The EHT to the >CRT is isolated as well, by the flyback transformer. > >Of course these means that one yoke winding is isolated from the power >line, the other isn't. Adds the 'fun' when servicing these. Isolation transformer is the only way to live. Allison

23 years, 3 months

Another unknown system available in St. Louis

by west＠tseinc.com

I almost forgot to tell the list about this one.... if anyone wants it, it's theirs. I'll pick it up and facillitate shipping, or you can come to st. louis and go to the store and grab it yourself. At another electronics surplus store in st. louis....this appears to be a cpu only, could be a cpu and disk drive. 19" rackmount, brushed aluminum type front panel. The brand says "Bruker" on it. There's a row of lights for IRQ (6-0), a row of lights for pending IRQ (6-0), lights for diskr, diskw, ION, RUN, POWER. There's two LED displays in the upper right corner, one for the PC and one for the Accumulator. Bottom right is a keyswitch. In the center are pad switches with embedded led's for things like single step, examine, store, etc. Then above that and in the center is a set of thumbwheels... they all were set at zeros, and I don't recall how many of them there was, maybe 12 or so... just on appearances and a walkaround without touching it I wouldn't be suprised if it was a core machine. It's high on a shelf in the storage area, they won't want to get it down unless I'm serious about buying it - it looks heavy. There's no price on it, but from past experience at this place I'm figuring the owner would ask about $35 bucks for it. The general outward construction and appearance looks very similar to the nicolet model 80 that I got there a while back and was (ISTR) shown at the last VCF. I've never heard of a "bruker" computer... I'm not interested in this system for myself, but for intellectual reasons I'm a bit curious if anyone has heard of this system and could tell a little bit about it. If anyone wants it, contact me off list. Jay West

23 years, 3 months

OT: help...

by ajp166＠bellatlantic.net

From: Tony Duell <ard(a)p850ug1.demon.co.uk> >> Doesn't even have an IEC cord set, strictly domestic. mains come in > >Odd.... Not really, domestic low cost version. saves a bit of money. >> Don't have to tell me. I've been kicked mor than once by Oscope supplies > >Yes, I know _you_ know, but this is a public list, and not everyone here >is used to working on high voltage stuff... True. I take it quite seriously. I was almost Blue Crossed 25 years ago when someone tried to help me while working on a 500W (output!) VHF commercial set. The turkey was thouching me when he reached into the plate compartment. We both flew about 12-15ft and he left via ambulence and if the combined shock and flight didn't hurt him I was going to. I was in some pain for days afterwards. >> No, most monitors these days can stand up without the cover and > ^^^ > can't ? Cant! confounded editor on this MS box like to go from insert to overstrike, very annoying. >True. It's often best to put them screen-down to work on them (and >certainly when removing or refitting the case). Trying to run them 'right >way up' with the case removed is a bad idea most of the time. that's the problem. though I do have a small carpet square to keep >from scratching the screen. >In the UK, almost all the circuity in a monitor (and most TVs for that >matter) is isolated from the power line. There's a 'hot' SMPSU, of >course, but the flyback, video circuitry, etc are all isolated by the >chopper transformer. True in this case but many TVs are not. I have a color set I have to look at (color skewed to red) that is very unsafe... isolation Xfmer time. >I've heard that a lot more of the electronics in US TVs is 'hot' >(compared to what I am used to) -- surely that's not true of monitors as >well.. Yes! >That doesn't necessarily mean the capacitors are still good. Particularly >not with the cheap components used in consumer electronics. I'd be more >inclined to trust a 20-year-old capacitor from an HP or Tektronix >instrument than a 5-year-old one from a PC monitor. No arguement. We retired a leader LBO505 Oscope as unstable calibration due to bad caps yet the Tek 316 is still going strong and in calibration! Allison

23 years, 3 months

Amsat-Golem article - redux

by rcini＠optonline.net

Hello, all: Happy New Year to everyone. I'm trying to do some rearranging on my file archive, and I can't seem to locate the scan of part 2 to an article in BYTE magazine about the Amsat-Golem S100 computer. Whoever scanned this for me and e-mailed it to me, if you could re-send it. I'd appreciate it very much. Thanks again. Rich ClubWin! Group 1 Collector of Classic Computers Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /*****************************************/

23 years, 3 months

VT78 - pinouts

by pete＠dunnington.u-net.com

On Dec 30, 23:06, David Gesswein wrote: > From: pete(a)dunnington.u-net.com (Pete Turnbull) > >That wasn't what I meant. Berg label the connector pins starting from the > >opposite end of the connector from the rest of the world, so what I meant > >was that on actual connectors, the pins are: > > > ... > > Thanks, I have updated the document. I had less trouble building it in the > first place than figuring out what I built. LOL! I often find that :-) > The adapter has a normal > 3M in it and I had though I got the pin 1 backward on it. Apparently > when I built it I knew they were opposite but since forgot. The first couple of times I came across Berg connectors (rather than, say, 3M, which I was used to on micros) I was *thoroughly* confused by what I saw as the "wrong" way of doing it. A healthy dose of DEC machines with 3rd party parts fixed that. Now I use them less, I have to think about it again, though. I wonder how this confusion came about? Everyone else uses "stripe on the right" (but not, IIRC, for D-connectors and some others) but I think Berg predates 3M et al headers? If so, how come 3M and the rest chose to be different? -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York

23 years, 3 months

IBM-PC and SCSI

by lgwalker＠look.ca

I recently picked up a Fujitsu M2266SA HDD. This is a 1M SCSI 5 1/2 " drive with a black bezel like the IBM-PC MFM drives and will fit in the same space. The vendor said it was SCSI-1 but TheRef says it is SCSI-2 and Fujitsu doesn't say. I have a heavily modified PC(5150) with an Intel 386 Onboard card as Allison has on her Leading Edge 8086 (BTW, I have a lead >ajp < to someone that has the mem-expander daughter card) However I have no info on whether it would be possible to add a SCSI card to an IBM-PC. I have an Adaptec 1522A ISA SCSI card and likely others in my card box. Was there a SCSI card for the PC ? If so, would this possibly, with this configuration, allow you to transcend the 5-slot limits of the PC. And of course to have 1 meg storage for programs. WHEEEEE!!! Am I in fantasy-land or could I have a system to confound the leading-edgers, altho it already does that. "NO IT ISN'T POSSIBLE ON SUCH AN EARLY COMPUTER" . He he he he, chortle. ciao larry Reply to: lgwalker(a)look.ca

23 years, 3 months

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test-drb December 2000