All,
Background: In 2005 Al Kossow supplied me with several thousand SDS 940 files extracted from archival tapes. I attempted to bring a system up using Bob Supniks excellent SDS 940 simulator, but became frustrated with what appeared to be several missing pieces of the monitor. After failing to locate additional 940 tapes in the basement of the NBS Radio Building in Boulder where we used to store them in the 1970s, I put the project aside, being more than full-time employed then. In 2010 I retired and moved to Mexico. I did not pursue the 940 project until a former NBS colleague, Howard Bussey, broached the subject in January, 2014, with suggestions of alternative approaches. In turn, that prodded me to write a number of tools to scan the file collection looking for needed components of the Monitor and Executive, and to create a simulated drum. Debugging and development has continued intermittently for the last 14 months, resulting in a state of work that perhaps merits wider discussion of where to go with it, and whether anyone else wants to join my efforts. At the end of this e-mail are my notes on the current project status. In summary, I have a nice running SDS 940 time sharing system with components to edit, assemble and link code. In the eating your own dog food department, I can assemble, link and run the system and make changes to it; no cross-assembly necessary. I have no doubt that if I installed the simulator on a Raspberry Pi attached to my router, any of you could telnet in and have a productive session. Theres still a lot to do in terms of finding and building the remaining subsystems like FORTRAN, BASIC and SNOBOL. Getting the system built with a permanent hard disk file system instead of the drums temporary file system would make this easier, not having to copy files from the host each session via simulated paper tape. Does anyone think theres sufficient interest to make this a GITHUB collaborative project? Or should I just labor away as time and energy permits? For privacy reasons, I cant make the multi-thousand file archive public, because theres personal information such as resumes buried among the archives that must be searched for relevant source files. However, I could put on GITHUB just those files Ive found as well as the tools Ive developed. The effort to manage a GITHUB repository would only be worth it if others contributed. As a distribution system to just a few folks, I can do that more easily as a zip file. Many thanks to Al Kossow for the original tape files, to Bob Supnik for an excellent simulator, to Mark Pizzolato for his patience with my many screwups sending bugfixes to the SIMH archive, and to Howard Bussey for poking me to give this another try. Mark Emmer Pátzcuaro, Michoacán, México --------------------------------------- Received about 2,470 extracted files from the L16x tape set. These included source, binary, save and dump format files. Wrote a number of C tools to find needed code amongst the memory save files and to convert to formats needed by the simulator. By finding memory save image files of needed components, was able to build a simulated drum with the Time Sharing System's Monitor, Exec, user directory and these functional applications: NARP - New ARPAS Assembler DDT - Linker, loader, debugger QED - Text editor CAL - Conversational Algebraic Language LISP - LISP programming language CCP - Conditional Command Processor Can transfer files between the host O/S and 940 exec via paper tape reader and punch. Files are stored on drum. Multiple simultaneous users can be accommodated via multiple telnet sessions. CCP program that stuffs input to and steals output from a pseudo teletype to process command files works properly. Can reassemble and link the Monitor and Exec and install on drum using a CCP command file. Have created a paper-tape bootstrap to load the production or debug monitor from the drum based on console breakpoint switch setting. Fixed various errors in the 940 simulator that caused Monitor, Exec and subsystem malfunctions. To Do: 1. Rebuild Monitor and Exec to include support for Data Products or Bryant movable arm disk to provide permanent file storage. 2. Attempt to build all applications from source files. In addition to those listed above, need to find source files to build: OLDDDT, SNOBOL3, SNOBOL4, QSPL, RUNOFF, BASIC, FORTRAN II, FORTRAN IV and MAIL. Will add them to the Exec command tables to make them built-in commands, rather than applications that are launched by the GO TO <savefile> command. 3. Find the OPER program so can manage users and file directories. 4. Find the NEWTAPE program to properly initialize a mag tape with a file directory. 5. Get the Monitor and Exec assembly symbols that are saved on drum to work properly with DDT so can debug/inspect a running or crashed system. The mechanism used was designed for OLDDDT, which so far I have not been able to locate. 6. Having the QSPL compile running will allow investigation of the many QSPL source programs in the collection. 7. Comb through the 2,470 files as well as files on the L14x tape set for other interesting programs. For example, L14x appears to contain files for PCAP, an early class scheduling program, with data files that make it look like it was used by the E.E. department at UCB. 8. Create a front panel display for the running system. Failures: 1. Never could build a proper mag tape image that would work with the system. The system build was for a RAD/tape system with no disk storage. This SDS release uses an overwrite-in-place mechanism to maintain a random-access read/write file system on tape, complete with user directories. Never did find the NEWTAPE program that's supposed to initialize a tape, and all attempts to create a binary tape image that would satisfy the Exec's tape mount command failed. While I can boot a system from a mag tape image file, all file transfers between the host and the TSS have to be accomplished via simulated paper tape. Blue-Sky for someone else To Do: 1. There's a build switch in the monitor for SRI, and tantalizing hints of code for Douglas Englebart's NLS, such as finding that the SMT (Shared Memory Table) reserves 8 drum pages for NLS. Theres 940 code in the monitor to interface to a PDP-5. However, to date, no source code has been found for NLS. To duplicate the original SDS 940 hardware implementation would require a PDP-5 simulator with associated CRT display and information on how it was attached to the SDS 940.
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