RSX11M+ on SIMH - SYSGEN "separates the men from the boys"

Parent Category: How-to's Category: Getting RSX11M+ running on SIMH Written by Administrator

My company is an agricultural trader and processor of grain and oilseeds. They trade billions of dollars worth of commodities on various exchanges such as the Chicago Board of Trade, Mercantile, Comex and several other commodities trading houses. In 1980, it was the early days of computer networking and our company was building a proprietary trading system that consisted of a pair of PDP-11/44s running RSX 11M linked by DMC-11 one megabit links with 8 direct data line feeds from various exchanges. The 11/44 pair had a hot fail over capability on a DT07 bus switch which then fed a network of 12 PDP-11/23s running RSX11S (downloaded over the network). The 11/23s were located in various parts of the world, and each fed around 20-24 VT100s for in total a couple hundred commodity traders with individually customized screens fastest, most current information about the price of corn, soybeans, wheat, world news, etc. All these PDP-11s ran Macro-11, reentrant code that used early forms of DECnet task to task data communication over 9600 baud lease lines to deliver the most up to the second, realtime data available. The programmers for these RSX PDP-11 systems were rough, tough, experienced guys who had worked on projects such as the U.S. Air Force's SAGE system in the early 1960 (see Inside IBMs 67 billion SAGE).

As a new chemist in the research department I bought a PDP-11/24 to gather data from laboratory instruments. So I went down to the IT department to borrow the RSX11M V4.0 distribution from the guys who were running our corporate PDP systems.

And I got laughed at for thinking I could do a SYSGEN with no training. These guys were "skeptical" that someone with so little computer experience, who wanted to write programs in "Fortran" (not "machine language"), could master the complexities of the RSX SYSGEN. In fact, they told me that SYSGENs separate the men from the boys. That's because the early RSX SYSGENs were quite complicated. The distribution was on five RL02 10 MB disk packs and you had to change them at various time and a single mistake could mean you had to start over. Also, the process might take 6 to 8 hours on those old slow systems often done as an “all-nighter” in the computer room.

Fortunately, for me that chemist, DEC had been working to make SYSGEN easier (with RSX11M V4.0) and even though it still took five RL02 disk packs, and about 6 hours, it was much easier than it had been in the past. Well as easy as it could be given that you are building the operating system from it's source code in those times.

Today SYSGEN is not nearly as complicated and on my iMac running Ubuntu on VM/WARE takes less than 5 minutes for computation. 

The PDP-11/44 photo is below:

pdp1144

 The peripherals were from left to right were the communications cabinet with 9600 baud leased lines to other PDP-11s in other states, and 64 lines of RS232 for terminals, printers, and laboratory data acquistion. Next was a RL02 and a RX02. Then two RL02s and a 5 inch expansion bus cabinet which had a DMC-11 1Mbs link to another PDP-11/44 doing process control in a fermentation plant next door. Then the PDP-11/44 with the built-in TU-58, then a pair of RK07 disk drive cabinets and lastly a TS11 tape drive.

    I could pull the plug on this 11/44 system wait a few minutes, plug it back in and at most we would loose a key stroke or two in edited files. RSX had special code that when the Unibus AC low signal occurred could get a number of things done before the big capacitors lost power and then the DC low signal would occur and it would retract disk heads and fold up shop, until the power came back on and it went through its power recovery sequences.  

Unfortunately, I could not find a photo of my 11/24 with its RL02s by itself, but the photo below is the original PDP-11/24 and the 3 RL02s it had along with some RL02 disk packs on the rack behind it. The photo was taken just after I acquired the PDP-11/44 used from our IT department so that I could migrate to RSX11M+ from RSX11M (you really need a I/D space PDP for M+). I found a buyer for the 11/24 and had the buyer send the money to a college where I bought the two used RK07s which weighed about 180 kg each. 

pdp1124

 And finally here is some of the laboratory equipment connected over RS232:

chromatograph spectrometer chromatograph

A High Performance Liquid Chromatography system

Nicolet Fourier Transform Infrared Spectrometer and a Hewlett-Packackard Gas Chromatograph