The Sigma Years

1967-1970 
Employer:
     University of Houston

One program I did for this machine was a stand alone (bootable) program to save and restore a "RAD" unit to tape. (RAD means Rapid Access Device. It was a fixed head disk.) Operations used the program to restore the RADs if the operating system would not boot.

I also modified the operating system to handle EOTs (End of Tape) as well as other OS enhancements to make life for the users easier.

BTM (Basic Timesharing Monitor) was UH's first time sharing system. It used teletypes as terminals. It was interesting since it only used 16K of high memory and swapped user memory in and out to the RADs with concurrent I/O i. e. writting out the previous user at the same time it was reading in the next user. It supported Basic and Fortran development in a time sharing setting. It supported 16 concurrent users.