test-drb November 1999

test-drb@ccmp.vtda.org

211 participants
749 discussions

by edick＠idcomm.com

SInce I sometimes take testing fairly seriously, I have several meters with several slightly different diode testing modes. I've found none which indicate a bad diode is good, nor do any of them indicate a good diode is bad. One of my testers is something I built for matching diodes, and and transistors, and it runs a pretty constant 1.26 or 12.6 ma (from an LED biasing a 2N3904) through a diode, and a panel meter displays the forward voltage. Not one of my meters exhibits behavior as described by "Wizard" however. I can't imagine what the problem is, but I agree that digital meters can produce unpredictable results when used in a way not intended by the designers. Generally speaking, the DMM is a Digital Panel Meter with a fixed reference voltage built into it, looking a the output of an analog or even mechanical switch, the purpose of which is to run the appropriate current through/into the component under test to generate a voltage scaled to display a value reflecting the value of the component under test. In the case of diode test, that's really easy, since it's a current within a fairly forgiving range, and which will, with most any diode produce a voltage reflecting what that particular diode drops at that current. Almost all measurements can easily be done in this way. Voltage is easiest, of course. Dick -----Original Message----- From: sms(a)antinode.org <sms(a)antinode.org> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, November 03, 1999 4:40 PM Subject: Re: schottky diode again.. >> From: "Richard Erlacher" <edick(a)idcomm.com> >> >> If you have a diode of any kind which behaves more as a resistor and less as >> a diode, i.e. it measures more or less the same in both directions, though >> differently on different settings on your DMM, I'd say it's broken. > > I'd say you have a modern meter, and neither of you knows how to use >it. The "diode" range on the meter is there because the other >resistance ranges are not useful for testing diodes. Read the manual >for the meter, or buy a curve tracer, or build a continuity tester from >an old flashlight (two-cell preferred), or ... > > I'm curious. Have you tried the same family of (mostly misleading) >tests on a known-good, plain-old silicon diode? > >> > From: jpero(a)cgocable.net <jpero(a)cgocable.net> >> > ... >> > says "good" but I know it's very low current also low voltage so that >> > would usually not screen out sick diodes. > > The current and voltage for the resistance ranges are probably much >lower, which is why the readings are so useless. (Repeat previous rant >here.) > >> That why I used resistance ranges just to be sure. > > This must be some new meaning of "sure". > > There are some subtle defects possible in a diode which will not be >revealed by the "diode" test on a multimeter, but that's almost >certainly the best test offered by the meter. > >> Wizard > > Apparently a misnomer. > >------------------------------------------------------------------------ > > Steven M. Schweda (+1) 651-645-9249 (voice, home) > 1630 Marshall Avenue #8 (+1) 612-754-2636 (voice, work) > Saint Paul MN 55104-6225 (+1) 612-754-6302 (facsimile, work) > sms(a)antinode.org sms(a)provis.com (work)

25 years, 1 month

Gridpads on epay

by Innfogra＠aol.com

I noticed a couple of Gridpads on epay that are closing in 6 hours. Current price is $31 and it hasn't changed in over 24 hrs. Item number 187950991 Paxton

25 years, 1 month

VMS architects

by mbg＠world.std.com

>> Sorry... the Nivenisms are: >> >> TANSTAAFL - "There Ain't No Such Thing As A Free Lunch" >> >> Megan Gentry >> Former RT-11 Developer > >Sorry, That one's Robert A. Heinlein. Yep, sorry about that... 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, 1 month

Help: Identify DEC/Dilog Modules

by mcquiggi＠sfu.ca

Hi Groups: I have some DEC modules that aren't in the latest Field Guide (thanks to Tim Shoppa for bringing this up to date). The identifiers are: M7684 M7773 M7774 M7776 M7786 M7787 I also have two questions: 1. I have a M7133 Unibus 11/24 CPU. As it's a single card CPU, does it still need a custom backplane, or is this a leter model CPU that can fit in a standard SU or something like that? 2. I have two Dilog controllers, the DQ236 and the DQ256. The Q for Dilog generally indicates Q bus. These have 1 x 60 pin header and 4 x 26 pin headers on them. Disk controllers? What type of drives? Any info appreciated, Kevin -- Kevin McQuiggin VE7ZD mcquiggi(a)sfu.ca

25 years, 1 month

Data I/O programmers (was Re: EPROM sideline)

by mranalog＠home.com

Ethan Dicks <ethan_dicks(a)yahoo.com> wrote: > --- Eric Smith <eric(a)brouhaha.com> wrote: > > "Richard Erlacher" <edick(a)idcomm.com> wrote: > > > The OLD Pre-Unisite (model 2900 ??) programmer from DataI/O... > > > > You're thinking of the model 29 (and 29B). They've been out of support > > for quite some time, and they recently removed the last technical info > > (such as family and part codes) from their web site. > > Does anyone have this info? I have an old programmer under the bench that > I have check, but ISTR that it's a model 29. As I started reading this thread, I went up to the Data I/O file download area and realized in horror that those family and part codes text files were gone! (The "old" directory under ftp://ftp.data-io.com/dataio/device.lst is gone) Someone should host these files! I started searching my hard drive and some backup CDs for files with "22" in them. And I did find the family and part codes text file for the "Series 22/A", but I could swear that I also downloaded a zipped file of all of the old programmer support files from the Data I/O site. I just can't what it might have been named. Can anyone convince me that I'm not just imagining this? And Arlen Michaels amichael(a)nortelnetworks.com said: > I've just bought an old Data i/o series 22 programmer but it lacks a manual. > Data i/o have indeed removed all tech support for older models from their > website. Does anyone know an alternative site still offering manuals? I have a couple Series 22 programmers (and a optional RS-232 paper tape reader, built-in UV eraser,and 351A-064 socket adapter for those little PROMs like the 82S123 :). And I also have a manual, contact me at dcoward(a)pressstart.com. Or if you're already famillar with operating the Series 22, I could just scan the little "flip book" operator's manual. I have flip books for the 22B (What is the 22B?), Series 22, and the 29B. I don't have a regular manual for my 29B. One of these days I need to create a cheat sheet for operating the Series 22 because every time I need to use it, I spend half an hour in the manual (especially to set-up remote operation with a PC). --Doug ==================================================== Doug Coward dcoward(a)pressstart.com (work) Sr. Software Eng. mranalog(a)home.com (home) Press Start Inc. http://www.pressstart.com Sunnyvale,CA Curator Analog Computer Museum and History Center http://www.best.com/~dcoward/analog ====================================================

25 years, 1 month

schottky diode again..

by jpero＠cgocable.net

Sheesh, that topic wandered off the diode discussion! Snip! The important thing I wanted to hear about is how schottky diodes reacts if good and what it's like when bad or sick on a DMM with different resistance scale settings used, diode test also seems says "good" but I know it's very low current also low voltage so that would usually not screen out sick diodes. That why I used resistance ranges just to be sure. Yes, I pull diodes and transistors out for checks to be sure. Ingore the battery thing please. I'm more concerned getting the notebook going. Thanks. Wizard

25 years, 1 month

Info about Alpha Micro 1021, HP terminal, 8" floppy

by amichael＠nortelnetworks.com

Don't know about the 1021, but I've got an Alpha Micro 1042E. Got it from an automotive parts business that used it for inventory and order desk: it's got a raft of RS-232 ports on the back to timeshare an office full of terminals. The 1042E is an S-100 box (but BIG enough to hold its 8" Winchester) with a 68K cpu card and an unusual tape backup interface card (it uses a modified videocassette recorder). So I suspect it would be worth digging inside to see if the 1021 is likewise S-100. The operating system is AMOS which is somewhat like DEC's RT-11. I don't have any documentation. I can't figure out how to get code into it: it has no floppy drive. Maybe Alpha Micro distributed everything on videotape (charging extra for New Releases or Oscar winners?). > -----Original Message----- > From: McFadden, Mike [SMTP:mmcfadden@cmh.edu] > Sent: Tuesday, November 02, 1999 10:17 AM > To: Discussion re-collecting of classic computers > Subject: Info about Alpha Micro 1021, HP terminal, 8" floppy > > Any info on these mature computer components? > > I was looking in a stack of pallet sized boxes at the local computer > surplus and I came across a Alpha Micro 1021 computer. It appears to be > about 2' by 2' by 1.5' with a series of DB25 connectors on the back. I > couldn't move the top box to gain access to the lower box. I couldn't see > much more than the exterior. > <snip> -- Arlen Michaels amichael(a)nortelnetworks.com Nortel Networks, Ottawa, Canada voice (613) 763-2568 fax (613) 763-9344

25 years, 1 month

Apple ][ + but no Floppies

by rhudson＠ix.netcom.com

On 11/02/99 22:59:13 you wrote: > >> I just managed to get control of the machine while checking out a "Games" >> disk and I now have DOS 3.3 >> >> How can I transfer the Binary files (non basic) to my newly formatted disk. >> All it has is a HELLO basic program. (like INTBASIC and FPBASIC and D800 >Do you actually have INTBASIC and FPBASIC files on a disk? If so, then you >probably have the DOS 3.3 System Master disk, which comes with a handy >file-copying program called FID. > >There is also a COPYA program which copies entire disks -- that may come in >handy as well. > >-- Derek > drats I don't have either of those...they weren't on the games disk. :^( (missing out on all the prommise of my powerful new Apple][+ )

25 years, 1 month

Northstar Horizon

by edick＠idcomm.com

Well, I don't know what instructions were used to move the SA1004 contents to the BBRAMDISK, but it didn't take long to write in MBASIC and compile with BASCOM. It was pretty similar to the formatter, since that was written the same way. The odd thing was, since I wrote a lot of assembler back then, the ASM version of that program, or of the formater, for that matter, was not noticeably faster than the BASCOM version. Both were probably being held up by the drive. Nowadays, the 8MB ramdisk would be dirt simple, using one simm and one CPLD, and a small one at that. There was, by the way, an outfit nearby, which produced, among other things, a 10MB RAMDRIVE for the TI-PC. That product was interfaced via SCSI and was moveable between systems. It must have lived on a battery as well. Dick -----Original Message----- From: allisonp(a)world.std.com <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, November 03, 1999 6:53 AM Subject: Re: Northstar Horizon >> I even have a 32K card with battery backup on board. I also built a RAMDISK >> with a battery backup so I could dump an entire SA1004 to it in one stroke >> and keep it alive with a couple of motorcycle-battery sized gel cells and a >> major DC-DC converter. I built one for a business partner and hooked up >> solar cells and one of those adjustable DC-DC converters (one of the old, >> Old, OLD Boschert adjustable open-frame types) to bring the 60 Vdc or so >> down to 14Volts and another to build the 5 Volts from that. > >At the time I did the RomDisk I also did a ramdisk (io port addressable) >not unlike the Compupro Mdrive. the difference was I used Mixmos static >ram and used 4 AA (500mah) nicads to keep it alive for up to 100hours. >Total ram was 128k. A later design used 2kx8 EEPROM and Cmos static rams >for 128k for each "drive". > >I also have two BPK72 bubble memories (128kb each). > >My current project is a dual semiconductor disk for S100 use 1mb or >flashram and 8mb of Dram battery backed up. Both addressable Via port >addresses (uses otir/inir to read write blocks). With current 1mb 30 pin >simms and FPGAs it's not a dense board. I used 1mb 30 pin as I can get >then for near nothing. Whats nice wth that config is I can preload it >and then plug it into another system and read/write it easily. > >Allison >

25 years, 1 month

Northstar Horizon

by edick＠idcomm.com

I did some similar fooling around by populating an SRAM card with battery-backed rams. It wasn't worth it at the time, though. I even have a 32K card with battery backup on board. I also built a RAMDISK with a battery backup so I could dump an entire SA1004 to it in one stroke and keep it alive with a couple of motorcycle-battery sized gel cells and a major DC-DC converter. I built one for a business partner and hooked up solar cells and one of those adjustable DC-DC converters (one of the old, Old, OLD Boschert adjustable open-frame types) to bring the 60 Vdc or so down to 14Volts and another to build the 5 Volts from that. Dick -----Original Message----- From: Allison J Parent <allisonp(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Tuesday, November 02, 1999 6:48 PM Subject: Re: Northstar Horizon ><Nowadays, it's really tempting to use an EPROM or Battery-Backed SRAM to ><hold the entire CP/M CCP, BDOS, and BIOS, and let the warm boot reload the ><CCP from there. That would certainly make the control-c quicker. > >Nowadays! I did this back in early 81 using 2732s. I put a monitor, bios, >ZCPR2 and BDOS in that. The CCP and BDOS only eats 5.5k. It was set up >rather odd as the system runs from a small 2716 at cold boot with a monitor >and then by user command loads the 8k image into ram from IO addressed >"romdisk". The CTRL-C was very fast as it could do INIR copies from the >rom. A later version still running is 256k of eprom (27512s) had all of >cpm, loader, ASM, VEDIT, SID (and more). This version the boot EEprom >is at 0000 and is truncated bdos, bios and a loader. This was done so that >I could have it load CPM.SYS image for testing from the selected drive >including the ROMDISK. This is raw speed. > >Allison > >

25 years, 1 month

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test-drb November 1999