test-drb December 2007

test-drb@ccmp.vtda.org

215 participants
420 discussions

Have the microvax user diag tapes been imaged?

by aek＠bitsavers.org

I have a couple that are sticky/shedding. Before I spend a lot of time trying to recover them, has someone imaged them already? They are from 87-89.

16 years, 3 months

ST506 and/or ST412 hard drives

by ard＠p850ug1.demon.co.uk

> > Hi, > > I am restoring a Vector Graphic computer and would like to add a hard > disk drive. The controller only supports two kinds of hard disk > drives, the ST506 and ST412. The HD controller is hard coded to > support these DRIVES not just a compatible interface and relies on a > special signal present only in these actual drives. What signal is that? I've looked at the schematics for thsoe (although not recently) and I can't remember any extra signals on the connector. Can this signal, if it exiasts, not be 'faked' on some other drive? -tony

16 years, 3 months

Mail formatting

by ard＠p850ug1.demon.co.uk

> > One of the recurring issues of ASCII is: > > "What is the ASCII code for newline?" > > What I've heard---there is no one character that returns the carriage to > the start of the line (CR) and advances down one line (LF). MS-DOS seems to That, indeed, is how the Teletype 33 behaves. And 5-level teleprinters normally had separate CR and LF codes that acted in that way. > think both are required, whereas Unix went with one (LF) and add both if > required in the driver code. The older versions of Mac OS (prior to being > Unix under the hood) used CR. And while I wrote code to handle CR, LF, TRS-80s used CR only IIRC. In fact they _sent_ CR only to the printer as standard, which could be a a problem if you had a non-Radio-Shack printer, or if you wanted to use an Radio Shack printer on some other machine. There were 'filters' for some TRS-80 OSes to add the LF. Most older printers had an internal DIP switch to set an 'Autofeed' -- that is to do a linefeed (as well as returning the carriage). There was also a pin on the Centronics connector to enable/disable this feature. IIRC the BBC micro has a operating system call to set the 'printer ignore character'. At power-on this was set to 0x0A (LF). I think the OS would try to send CR LF, the printer driver routine would then delete the LF so that only the CR got through (requring a printer that did an autofeed), then you could change the 'ignore' character to something else if the printer neeeded both CR and LF. The HP9866 is a thermal line printer (prinhead the full width of the paper, but only one dot high). From what I can deduce from the scehamtics, it ignroes CRs totally, when it gets an LF it springs into life and prints the contents of its buffer. > CRLF, LFCR, I never did see LFCR in the wild. I think I did, once. Really confuesed a bit of software I was using too... > > Another recurring issue for ASCII: what is baskspace supposed to do? > I'm used to systems that use $08 [1] to move the cursor left one column and > overwrite the character there with a space. But Linux (maybe because Linus > was secretly a DEChead?) decided that $7F would move the cursor left one > column and overwrite the character there with a space, but X Windows (which > I use on Linux) seems to want to use $08 for that. I beleive the original intention was that 0x7F would be _ignored_. The point being you could overpunch any characeter on paper tape to turn it into 0x7F (all holes), and thus you could effectively delete that character from the tape -tony

16 years, 3 months

Wanted: PDP-11 MUMPS Software & Manuals

by James＠jdfogg.com

> Hi, > > I'm looking for Software & Manuals for any of the MUMPS implementations > for the PDP-11, > e.g. MUMPS-11, DSM-11 or M/11+. > > Can anybody help? Intersystems in Cambridge Massachusetts, USA was the last company to own/publish this software. They may still support it. My older brother used to maintain their Data General and UNIX versions.

16 years, 3 months

Modem to modem without a line simulator

by ard＠p850ug1.demon.co.uk

> > > This question is bugging me from another forum. > > Is it possible to connect two modems (eg: Hayes 2400 to Hayes 2400) > using a 'dead' or isolated pair of copper wire and have them be able to > communicate? > > I always thought that this can not work because the line that the modems > are connected to has to have some current. The phone system works > because an action on one end of the phone (talking into the carbon > microphone) causes a reaction on the other end. Without some sort of > current on the line, how can this work? Hence the need for 'line > simulator' circuits Most direct-connect modems do not require any power from the telephone line -- in fact the modem circuitry is coupled to the line through an isolating transformer, which is iteself capacitor-coupled to the line. So the DC conditions on the line have no effect on the modem circuit Of course such modems do 'loop the line' (provide a DC path between the 2 line wires) when off-hook. But that's to tell the telephone exchange that the modem is indeed off-hook, not for any particular requirement of the modem So if you can get onee modem to ignore the lack of dial tone/rigning tone, andthe other one to answer without seeing a rining voltage on teh line, then just connecting them together should work. I think there have been a few -- a very few -- modems that do requeire a DC voltage on the line for correct operation. Foe those, you can often fake it by connecting a suitable DC supply in series with a suitable limiting resistor between the line wires. > > Some people are claiming that it works without the line simulator. I'd > like to understand why. > > (I could get out the multimeter if things get really desperate, but > maybe somebody can tell me that the line current thing only applies to > acoustically connected modems, not direct connect. Or the direct > connect modems put enough juice on the line to make it work. Or > something else that might make sense.) Telephones, of course, do draw power from the line, which means accoustically-coupled modems need line power for the asscoicated telephone. -tony

16 years, 3 months

Compaq "Enhanced II Keyboard" - what's with these?

by listmailgoeshere＠gmail.com

Hi list, I have two "Compaq Enhanced II Keyboard"s here (they look old enough to be on-topic) - PS/2 connector, but they don't work on any PC I've tried them with. Are these specific to one machine? If so, is there any interest before I dumpster them? Thanks, Ed.

16 years, 3 months

Any ideas what this machine was?

by Will＠Swaggie.net

Back in the early 80s, i worked as an assembler programmer for Reuters in London. I was involved with maintenance and development of software on two platforms - one was the PDP11, but the other was a much more obscure machine and i can't remember the name of the manufacturer. The machines in question worked together as a pair - we referred to them as "SGS", which stood for "Second Generation Slave". I believe they were designed as a front end for the IBM 360, but Reuters used them as, i guess, minicomputers. These machines were the heart of Reuters' oldest live stock and share price reporting system - and subscribers were able to check prices via a PDP8 in their office which was connected to the SGS pair. One of the pair was what you'd call a database server nowadays and the other did the comms stuff. As far as i remember, each machine was the size of three racks next to each other (which is probably what they were). The data was stored on a drum in one machine, and the other machine had a card reader and a teletype terminal. They both had paper tape readers. They were 16-bit machines and had a row of lights and toggle switches at the top of one rack, with a switch to change between memory location and data, plus an "enter/run" button. The data machine was booted by toggling in a paper tape reader bootstrap and then loading the drum reader bootstrap from paper tape, then booting the OS, which was stored on the drum. The comms machine also had a three stage boot process - toggle in paper tape bootstrap, read card reader bootstrap off paper tape, then read the OS from a stack of cards. I can't remember how we got the OS onto the drum now - but i do remember we did a lot of "patching" in memory, through the front panel, for debugging etc. These machines ran IBM 360 machine code and we did the development in 360 assembly language on an IBM 370, which was later upgraded to a 4340. Recently i've been trying to remember the name of the manufacturer of these machines, but i just haven't got a clue - although i'm sure i'd recognise it if i saw it. I've looked through computer history sites on the web, hoping i'd come across the manufacturer's name and recognise it, but i never have. So if anyone knows, or can give me any clues, i'd be grateful. I'm not subscribed to this list, so i'd be very grateful if anyone replying could Cc me. Thanks Will Kemp

16 years, 3 months

Rescue opp in Boston

by evan＠snarc.net

Just passing this one along for whoever's interested. >>> Xerox 820 II with 8" floppy disks, CP/M operating system, Select Word processing, and a 630 Daisy wheel printer. It was bought in 1982 and we have all the manuals. It has not been turned on since we "retired" it in 1989 or so, but it was working at that point. JoAnne Yates jyates at MIT.EDU

16 years, 3 months

ST506 and/or ST412 hard disk drives

by lynchaj＠yahoo.com

Hi, I am restoring a Vector Graphic computer and would like to add a hard disk drive. The controller only supports two kinds of hard disk drives, the ST506 and ST412. The HD controller is hard coded to support these DRIVES not just a compatible interface and relies on a special signal present only in these actual drives. If anyone has one or more of these hard disk drives they would like to sell me, please contact me or reply here. Thanks! Andrew Lynch

16 years, 3 months

Sun 3/60 - how to boot this thing?

by trasz＠FreeBSD.org

I just got a Sun 3/60, 8MB RAM, no disk. I have several questions: 1. Were these used with an external disk? There is some room inside the machine, but there are also several strange looking capacitors there. 2. With diag switch set to "norm", there is nothing (no output) on the serial console; the machine just blinks one of the LEDs. With diag switch set to "diag", the following appears: Boot PROM Selftest PROM Checksum Test Context Reg Test Segment Map Wr/Rd Test Segment Map Address Test Page Map Test Memory Path Data Test NXM Bus Error Test Interrupt Test TOD Clock Interrupt Test MMU Access Bit Test MMU Access/Modify Bit Test MMU Invalid Page Test MMU Protected Page Test Parity Test Memory Size = 0x00000008 Megabytes Selftest passed. Type a character within 10 seconds to enter Menu Tests... (e for echo mode) Is that a sign of EEPROM problem? Failed battery? -- If you cut off my head, what would I say? Me and my head, or me and my body?

16 years, 3 months

← Newer
1
2
3
4
5
6
7
8
9
...
42
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 December 2007