test-drb October 2004

test-drb@ccmp.vtda.org

245 participants
540 discussions

The myth of the memory effect- was: NMIH batteries - was: Re: HP 25 and HP55

by dave04a＠dunfield.com

Thanks for the info on NMIH. >2. NiCD batteries never had a memory effect either! I knew this would spark a thread on the existance or non-existance of memroy effect - I think they are a lot better now than they were (as are chargers), however Nicads (especially older ones) which regularily discharged only partly do lose capacity - I have observed it. >I think what can happen is that some cells discharge a lot sooner than >others, since in the real world the internal R is lower for some cells than >others. Since you are now pulling current *backwards* through at least one >cell in the stack, odd are good that some day one of the cells is going to >reverse on you, and become a highly inefficient inverted battery, one >that's unlikely to ever take an appreciable charge again. This is a >real-world problem for discharge devices that don't have both a timer and a >voltage monitor, and some ever sense temperature too. Yup - best way to kill a nicad "pack" is to fully discharge it - that is why I use individual cells, and discharge them in parallel through a diode - no cell ever goes below .7v. >Here's a battery maker saying No Memory Effect in currently produced product. Ah - the catch phrase is "currently produced" - As I indicated above, I think things have improved... but the Nicad cells I am using are 10+ years old. I can provide references to manufacturers telling you to be sure and fully discharge your cells from time to time as well ... it's a question that is still being debated, and nobody is going to convince anyone else either way - my personal experience is that calls which are carefully charged, and just a carefully full-discharged retain their capacity and last a lot longer than cells which are not fully discharged... Agreed thad modern NMIH cells do not seem nearly as "sensitive". YMMV. But ... we drift OT ... thanks for you input. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Vintage computing equipment collector. http://www.parse.com/~ddunfield/museum/index.html

20 years, 2 months

Classic OS's - EduSystem

by unibus＠gmail.com

> From: "John A. Dundas III" <dundas(a)caltech.edu> > In a bit of a follow-up to myself, I managed to locate one of the > mark-sense cards and the template I referred to earlier. Some > (crude) pictures may be view of each of theses at: > > <http://dundas-mac.caltech.edu/~dundas/retro/mark-sense.html> Very similar to the cards we used but not quite the same. Think the main body of the card was different. Unfortunately I can't lay my hands on a sample. Regards, Garry

20 years, 2 months

SGI monitors/kb/mice etc - anybody need 'em?

by Arno_1983＠gmx.de

Hello everybody, as ISTR from some discussions, SGI human interface devices are not easily replaceable by anything else and are in some demand because it is not unusual for a machine to arrive sans keyboard, mouse and/or monitor. University is decommissioning its SGI gear, so I have a chance to grab the following: Keyboard SGI No. 062-0002-001 Type RT6856T (2x) Mouse SGI No. 063-0009-001 (2x) Monitor (Type designation not available) (2x) Camera SGI No. 013-1577-001 (2x) Makes two complete installations minus the computers. These are long gone, so this is headed for the dumpster unless I call in. I'm not into SGI stuff yet, so it doesn't make much sense to keep it myself (unless somebody throws in a CPU for me :-) ), but I thought I'd offer it here. Don't know how much demand there'll be, so I see what comes in and then decide where it goes. This is basically give-away + s&h (I just wanna save it from the scrapper), but counter-gifts will not be rejected. Shipping is an issue (the monitors are big and quite heavy!), so local pickup is preferred. Er, yes, local to Erlangen University, Northern Bavaria, Germany, Europe. Yours sincerely -- Arno Kletzander Stud. Hilfskraft Informatik Sammlung Erlangen www.iser.uni-erlangen.de +++ GMX DSL Premiumtarife 3 Monate gratis* + WLAN-Router 0,- EUR* +++ Clevere DSL-Nutzer wechseln jetzt zu GMX: http://www.gmx.net/de/go/dsl

20 years, 2 months

OT: HP PA-8500 vs. AMD Opteron

by jwest＠classiccmp.org

Sorry for the off-topicness... I googled to find a comparison between these two chips with regards to relative performance and can't find anything. Can anyone point to a spot that has some definitive comparisons between the two? Figured someone here might know... Jay

20 years, 2 months

How to connect ASR-33 to a PDP-11 DZ11 Panel

by wacarder＠usit.net

I have successfully hooked up multiple terminals (two VT52s and an LA36) to my PDP-11/34 using an EIA DZ11 (M7819), and they are all working perfectly on my RSTS/E V7 system, which I SYSGENed for two DZ11s. I have also installed a 20mA DZ11 (M7814) and its associated distribution panel and now I'm ready to hook up a 20mA VT52 and an ASR-33 teletype. I have good documentation on the VT52 and how to get it connected, but the documentation that I have on the ASR-33 does not seem to show how to connect it to a computer. Can someone who has done this before give me some pointers? This surely is a trivial task, but I have not dug deeply enough into the documentation to find out how to do this yet. My ASR-33 works fine in local mode, punches and reads paper tape just fine, and now I want to hook it up to my system. Thanks for any help that anyone can provide. Ashley

20 years, 2 months

looking for pdp-11 assembler book

by jwest＠classiccmp.org

I'm looking for a particular book.... "PDP-11 Assembler Language Programming and Machine Organization" by Michael Singer, softcover I want this particular one for nostalgic reasons, it's the book I learned macro-11 on. I saw a copy on ebay, got outbid (so far), but it's with two other books I don't want. So before bidding further, I thought I'd see if someone has an extra copy for sale or trade. You can see a picture of the particular book above by going to ebay item 5131747255 it's the black (with blue/red/green splotches) book on the left. If anyone has an extra, please let me know! Jay West

20 years, 2 months

5 1/4" hard-sectored disk..

by jim＠smithy.com

I have some 5 1/4" hard-sectored disks that contain CPU microcode. They aren't 'formatted' with a filesystem, but are read with a simple board that contains some 9602's, a shift register, and a Z80. A dilemma: should I try to intercept the data from the board, write it to flash memory, and build a board to replace the whole Z80/hard-sectored disk thing, *or* try to build something to write the data stream out to another 5 1/4" disk. The Z80 doesn't care about the sector pulses - only the index pulse. So I could get away with a standard floppy instead of a hard-sectored one. The disk thing would allow me to keep using the original hardware, which would be nice, but I don't know the first thing about attempting to write the data stream back to the disk. I have no backups of the microcode disk, and no way to replace it when it dies. Every time I fire the thing up I feel I'm getting a little closer to it's death... Jim

20 years, 2 months

Hardware (What Interests me....) was : (PDP-8/s on e-bay)

by dave04a＠dunfield.com

>But then it still amazes me that I know many programmers who don't own a >'scope or soldering iron (and wouldn't really know how to use them >anyway), but I don't know a single hardware hacker who doesn't have a C >compiler and know how to use it. The best hardware guy I know (by a lot) barely does any software - doesn't know (or have) C, but has been known to do a quick-and-dirty BASIC program when he has to. He does however understand low-level software and how it relates to hardware very well - he has an uncanny abiilty to find the lowest cost way to implement something and still make it "reasonable" from a software point of view. [I'm officially a software guy, but I have 3 scopes and a couple of soldering stations (even a desoldering station) - but I do agree: most software guys I know are not like that] Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Vintage computing equipment collector. http://www.parse.com/~ddunfield/museum/index.html

20 years, 2 months

Flash ADC selection, or other approach?

by aek＠spies.com

The PC approach is to somehow wangle the five ADCs into the PC such that it will accept the 65536 5-byte (5-nybble) samples with ZERO LATENCY. -- The design I did for the analog 9 track data aquisition board uses five Analog Devices 10 bit dual 10megasample A/D's. These have parallel outs, and are synchronous (designed for direct IF amplifier digitization). The five are multiplexed into a FIFO which interfaces to a 40 pin cable to a PCI DMA IDE card. So, you end up with a ten channel synchronous data stream with a protocol that just looks like chained IDE DMAs.

20 years, 2 months

Classic OS's

by aek＠spies.com

Shorewood High School to a DEC timesharing system at the UW-Milwaukee... -- That was the system... Run by Prof. Len Levine, Richard Bartlein, Sam Millosovich and several waves of student volunteers (incl me..) Len gave pretty much anyone in Milwaukee an account that asked. He was responsible for a lot of folks in the SE Wisconsin area having their first exposure to computers. The User's Manual for UWM's TSS/8 is up at www.bitsavers.org/pdf/uwMilwaukee/UWM_TSS8_UsersGuide_Jul74.pdf

20 years, 2 months

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test-drb October 2004