On Aug 18, 2008, at 6:24 AM, Mike Naruta wrote: > Wow, RSX-11M? I haven't used that in a > quarter-century. Gary Unruh and I wrote > a 3GL for it that kept a big roomful of > data entry gals happy on a PDP 11/70 with > 2 MEGAbytes of memory. I even cobbled up > a clock card for it so I could run 45.45 > baud and copied the 20 meter RTTY autostart > net at the same time. I think I still > have a copy of my Baudot to ASCII converter > assembler program and the custom card. I > got pretty nervous changing the wirewrap > on that expensive CPU in order to get access > to my oddball clock card. I think it was > 150 baud that I hacked to 45.45 baud. Gary, > a veteran IBMer, was my mentor. What a guy, > brilliant!
I wrote a RTTY program that ran on RSX-11M using the DZ-11 mux board since it could be programmed to run at 5 bits, 2 stop bits and 50 bauds. It worked just fine talking to teleprinters running at 45.45 bauds. There was only 1/2 a bit of error by the time you got to the end of the character. There was a LOT of slop when sending and receiving 5-bit Baudot RTTY as the old model 15 and 29 teleprinters were never quite on-speed. Two stop bits ensured that the mechanical teleprinter had time to catch up before the next start bit. > I loved the way it kept the old versions > of your files and you could purge /Keep ;2 > to delete everything but the current version > and one previous copy when disc space got > tight. Yes, that was cute. I do think that hierarchical file systems are better, backups notwithstanding. If you like that feature check out ZFS. It provides that feature as part of the file structure thus allowing you to roll the file system or even an individual file back to any given point in time. When it does a write it does not write over previous data. It keeps the previous data indexed (journaled) so you can find it again. In essence you have a record of all the writes you have ever done to a given file. *VERY* cool. It is why I build my network-attached storage using Solaris running ZFS. (Solaris might be a good platform to run the SDR code as it runs on the same hardware, offers the same features as Linux, but has much better software quality assurance and patch tracking than does Linux. It is still too complex but seems very stable and pretty reliable.) > I used to have to key the bootstrap loader > program on the console switches in binary > to start it. I think I still remember the > program. Ah, you should have had one with core memory. You keyed the bootloader (do you remember the difference between the RIM and BIN loaders?) and it stayed in high core because core never forgets. Unless your program scribbled on the bin loader it was always there. The RIM loader was easier to key in from the front panel but the paper tapes were huge since the format of the tape was address:data/ address:data/address:data for each memory location. I had a BIN loader tape in RIM format. I would key in the RIM loader by hand then use that to load the BIN loader which I then left in core until my program ran amok and scribbled over it. DEC even had an early PROM-based loader. The "PROM" was a bunch of diodes you soldered in, one for each '1' bit. It had something like thirty-two 16-bit "words". Most people kept the RIM loader in that but some had a real disk bootloader. It would just issue the I/O request to the disk controller to transfer the first sector of the disk into low-core and then jump to location zero when it was done. Amazing what you can do with just 32 words. > Somehow I don't think the DEC 11/70 would be fast enough to do the > DSP. There was a floating point module you could plug into the Unibus. I had one on my 11/34. We used it in a simulation for tracking solar charged particles when they interacted with various planetary magentospheres. The problem was, the program took 11 days to run in real time. We ran it on RSX-11M because on power fail it would save state of the machine in core and then restart everything, including unfinished I/O's when the power was restored. This is why core was much preferred over MOS memory. > Any HP MPE fans here? Now there was an > intuitive system. Too bad the cryptic > UNIX killed it. I loved HP's TurboImage. I ran on HP 2100s and 21MXs. I forget the OS but it was very much like RT-11. (I think it was called RTE.) We were trying to automate the burn and intensive-care units at a hospital. My job was building dedicated uP-controlled data-collection units and interfacing them with the HP-21MX over RS-232. I learned a lot more about human physiology and pulmonary function than I ever wanted to know. I preferred event-driven, multi-tasking OS's like RSX. > > That was a bulletproof database. It > was lightning fast, if you kept up on > DB maintenance. In a decade, I only lost > one morning's worth of data to a crash. > This was before RAID. I remember one day > realizing that I hadn't booted the system > for a year and a half. Over 60 simultaneous > users. Try THAT with Windows. That is the point. We look at all this "advanced technology" in our operating systems and mostly what we have is something that is unreliable, incomprehensible, and barely maintainable. The excessive complexity makes it impossible to ensure correctness and guarantees that we can never have bug-free software. Monolithic operating systems like Linux, BSD, Windows, and Solaris make this problem worse. Simpler, distributed, more-or-less single-function processing units would be much easier to maintain and keep bug-free. A very simple message-passing microkernel architecture would be better. Brian Lloyd Granite Bay Montessori School 9330 Sierra College Bl brian AT gbmontessori DOT com Roseville, CA 95661 +1.916.367.2131 (voice) +1.791.912.8170 (fax) PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
