test-drb January 2015

test-drb@ccmp.vtda.org

175 participants
253 discussions

Operating systems of the 1970s handling dates beyond the year 2000

by jnc＠mercury.lcs.mit.edu

> From: Mark Longridge > I had to wonder if any of the older operating systems from the 1970s or > older could do this. > So, did any operating system programmers from this time period have > the foresight to use 4 digits for the year? It's probably worth distinguishing between the internal clock, the ability to set dates > 1999, the ability to print dates > 1999, etc. For instance, both Multics and Unix had an internal clock that ran correctly past the century end. (Although they do run out / roll over not too much later - in Multics' case, in 2039. For the Multics one, see here: http://www.multicians.org/jhs-clock.html for more.) However, in the case of Unix, both date setting and the canonical routine for date printing (separate code) didn't handle dates after 1999; for input, the year was only two digits, and for output, the first two digits were hard-coded to '19'. However, for calculating dates (which returned a vector of numbers), that part did theoretically work correctly for years after 1999 (it returned [$YEAR-1970]), but... There was a separate bug that caused the year calculation to fail in the closing months of 1999. Whether the person who wrote the code knew of the bug - it's a fairly simple one, an overflow of a short integer - I don't know, but it's possible they did, and on calculating when it would happen, decided that the fact that it would coincidentally also happen at century end meant it could be ignored at that point. However, once that was fixed, the date calcuation routine returned the correct year (without needing to change the interface). I don't know whether date input/calculation/output on Multics had similar issues: if you google "Multics leap year" it shows the source code for a couple of routines dealing with dates, but alas it's all in 645/6180 assembler, so I can't really grok it! It looks like it _might_ work, though (it seems to calculate the number of years since Multics' epoch - 1901 - and add that to 1901). If I had more time to expend, I could look at ITS too... :-( Noel

9 years, 11 months

the old VHS series on the history of computing

by sales＠elecplus.com

http://waxy.org/2008/06/the_machine_that_changed_the_world/ He found all 5 episodes, digitized them, and uploaded them. Cindy Croxton

9 years, 11 months

Sending 0377 via KL8JA

by cctalk＠beyondthepale.ie

> >I am noticing something odd in SimH when sending a 0377 (all ones) >character. It seems to be duplicating the byte. I haven't read anything >regarding this behavior. I'm away from my hardware PDP-8 at the moment, so >I can't confirm that this is not the behavior that I would experience on >the real thing. > It's not really that clear whether a telnet type connection is in use here but could it be something that does telnet negotiation is sending data to something which is not telnet negotiation aware? 0377 octal (FF hex) corresponds to IAC which would get sent as IAC IAC. Maybe monitoring the data on the network would confirm? > >Run 'nc localhost 2222 | od -to1' in a terminal, then 'go 200' and >repeatedly press 'c', seeing how many times it takes to generate a line of >characters in 'od'. Then, 'd sr 0376' and confirm that it takes twice as >many presses, indicating half as many characters being sent per TLS >instruction with the latter. > >Can anyone else confirm this for me? > Sorry - I don't follow that at all and figuring it out is probably above my pay grade :-) Regards, Peter Coghlan.

9 years, 11 months

more documentation...

by useddec＠gmail.com

I just looking for offers + shipping. Please contact me off list for more info or questions. I told Al he could have whatever he wants for free and I would pay shipping. Al, I hate typing, please take it all... NCR 801-0009975 801-0009981 powertec inc for GDI 3m lups module crt Buscher 0l400-3015r/4015r fisher controls type cp250 model sps-1878a allen-bradley 635344 ps cdc 83322310 54359803, maybe others... computer products (unipower) pwr div 800w multiple sc001-1442 MISC PWR SUPPLIES: tryger electronics uaro lear siegler GE century data condor Thanks, Paul

9 years, 11 months

TMS9918 (was Re: Seeking... TI TMS9902 ICs)

by spacewar＠gmail.com

On Sat, Jan 17, 2015 at 9:22 PM, Randy Dawson <rdawson16 at hotmail.com> wrote: > Later found their video chip 9918 Speaking of which, does anyone have the data sheet and/or user manual for the original TMS9918, *NOT* the improved 9918A? All my internet searches that turn up 9918 without an A suffix are in fact actually for the A part.

9 years, 11 months

Mystery ICs - AB 36D1024

by drlegendre＠gmail.com

Can't search up any data on these chips, they're marked with the Allen Bradley logo, and the code is 36D1024. Date codes are mid-1974. I have about 30 pcs. of them. But what are they?

9 years, 11 months

Shipping antique computers

by marc.verdiell＠gmail.com

Wow. Nice collection in a nice setting. I love the view of your commute. Where is your new shop located, still near Silicon Valley (near me ;-) )? Marc >Date: Sat, 17 Jan 2015 10:07:53 -0800 >From: Guy Sotomayor <ggs at shiresoft.com> >Here are some pictures of the stuff after I've moved it into my new shop but still on the pallets: >http://www.shiresoft.com/new-shop/Shiresoft/Almost_moved.html. > >TTFN - Guy

9 years, 11 months

Recovering Win3.1 Data

by dj.taylor4＠verizon.net

In the mid-90's I had a Packard Bell computer that ran Windows for workgroups 3.11. The computer is long gone, but I saved the disk. It is a 420 MB Conner. I recently tried to recover the data by attaching it to one of those IDE/SATA to USB devices and read it under Windows7, didn't work. I am able to copy files to floppy, but the stuff I want to save won't fit on a floppy. I put the disk in an old PC and it will boot to DOS, it tries to start WIN3.1 but exits because of some missing sound card hardware. What is the path of least resistance here? Is linux any help?

9 years, 11 months

VT100 Monitor Alignment Tool

by robert.jarratt＠ntlworld.com

The horizontal width on my VT101 needs adjusting, so I am in need of a monitor alignment tool (PN 29-23190-00). I have tried searching the web to see if I can found out what they look like so that I can improvise something but I have failed to find a picture of the DEC one. Does anyone have a picture of one? Is it just a long thin screwdriver? Is it the same as a generic monitor alignment tool like this one: http://eu.suzohapp.com/product/H92-0196-00/universal-monitor-alignment-tool- kit? Even so the picture on that site makes it hard for me to tell what I need to improvise something. Regards Rob PS The VT101 is partly working, I think the monitor control side is fine, but the terminal controller board seems to have problems, I only get random characters displayed when I power it up and it does not respond to any keys, not even SETUP L

9 years, 11 months

Seeking... TI TMS9902 ICs

by scaron＠umich.edu

Hi all, I'm looking to pick up a few TI TMS9902 ICs... this is an asynchronous communications chip for TMS9900 based systems. I'm considering the architecture for my next retro-SBC as I get closer to wrapping up my 6502 SBC, so, trying to put all the pieces together. Willing to pay a fair price. Thanks! Sean

9 years, 11 months

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test-drb January 2015