[Info-vax] OS Ancestry

[ni...@desmith.net]

Nice to get a mention in that. It was 40 years ago and the first bit of commercial s/w I wrote!

Nick
On Thursday, 13 May 2021 at 15:56:48 UTC+1, Arne Vajhøj wrote:

> https://en.wikipedia.org/wiki/RSTS/E 
> 
> <quote> 
> RSTS (/ˈrɪstɪs/) is a multi-user time-sharing operating system, 
> initially developed by Evans Griffiths & Hart of Boston, and acquired by 
> Digital Equipment Corporation (DEC, now part of Hewlett Packard) for the 
> PDP-11 series of 16-bit minicomputers. The first version of RSTS 
> (RSTS-11, Version 1) was implemented in 1970 by DEC software engineers 
> that developed the TSS-8 time-sharing operating system for the PDP-8. 
> 
> ... 
> 
> 1970s 
> 
> The kernel of RSTS was programmed in the assembly language MACRO-11, 
> compiled and installed to a disk using the CILUS program, running on a 
> DOS-11 operating system. RSTS booted into an extended version of the 
> BASIC programming language which DEC called "BASIC-PLUS". All of the 
> system software CUSPS for the operating system, including the programs 
> for resource accounting, login, logout, and managing the system, were 
> written in BASIC-PLUS. From 1970 to 1973, RSTS ran in only 56K bytes of 
> magnetic core memory (64 kilobytes including the memory-mapped I/O 
> space). This would allow a system to have up to 16 terminals with a 
> maximum of 17 jobs. The maximum program size was 16K bytes. By the end 
> of 1973 DEC estimated there were 150 licensed systems running RSTS. 
> 
> In 1973 memory management support was included in RSTS (now RSTS/E) for 
> the newer DEC PDP-11/40 and PDP-11/45 minicomputers (the PDP-11/20 was 
> only supported under RSTS-11). The introduction of memory management in 
> the newer PDP-11 computers not only meant these machines were able to 
> address four times the amount of memory (18-bit addressing, 256K bytes), 
> it also paved the way for the developers to separate user mode processes 
> from the core of the kernel. 
> 
> In 1975 memory management support was again updated for the newer 22-bit 
> addressable PDP-11/70. RSTS systems could now be expanded to use as much 
> as two megabytes of memory running up to 63 jobs. The RTS and CCL 
> concepts were introduced although they had to be compiled in during 
> "SYSGEN". Multi-terminal service was introduced which would allow a 
> single job the ability to control multiple terminals (128 total). 
> Large-message send/receive and interprocess communication became very 
> sophisticated and efficient. By August there are 1,200 licensed systems. 
> 
> In 1977 the installation process for RSTS was no longer dependent on 
> DOS-11. The RSTS kernel could now be compiled under the RT-11 RTS, 
> formatted as a kernel file with RT-11 SILUS, and copied to the system or 
> other disks, while the computer was time-sharing. The BASIC-PLUS RTS (as 
> well as RT-11, RSX-11, TECO and third party RTSs) all ran as user mode 
> processes, independent of the RSTS kernel. A systems manager could now 
> decide during the bootstrap phase which RTS to run as the systems 
> default KBM. By now, there were some 3,100 licensed systems. 
> 
> In 1978 the final memory management update was included for all machines 
> that could support 22bit addressing. RSTS could now use the maximum 
> amount of memory available to a PDP-11 (4 megabytes). Support was also 
> included for SUPERVISORY mode which made RSTS the first DEC operating 
> system with this capability. DECnet was also supported as well as remote 
> diagnostics from field service technicians at the RDC in Colorado 
> Springs, Colorado (a DEC subscription service). By the end of the 
> decade, there are over 5,000 licensed systems. 
> 
> ... 
> 
> BASIC-PLUS 
> Programs written in BASIC-PLUS ran under the BASIC RTS, which allowed 
> them up to 32K bytes of memory (out of 64K total). The language was 
> interpreted, each different keyword being internally converted to a 
> unique byte code and the variables and data being indexed and stored 
> separately within the memory space. The internal byte-code format was 
> known as PCODE - when the interactive SAVE command was issued, the BASIC 
> Plus RTS simply saved the working memory area to a disk file with a 
> ".BAC" extension. Although this format was undocumented, two Electronic 
> Engineering undergraduates from Southampton University in the UK (Nick 
> de Smith and David Garrod) developed a decompiler that could reverse 
> engineer BAC files into their original BASIC Plus source, complete with 
> original line numbers and variable names (both subsequently worked for 
> DEC). The rest of the memory was used by the BASIC RTS itself. If one 
> wrote programs in a language that permitted true binary executables such 
> as BASIC-Plus-2, FORTRAN-IV, or Macro Assembler, then the amount of 
> memory available would be 56K (8K allocated to the RTS). 
> </quote> 
> 
> https://en.wikipedia.org/wiki/BASIC-PLUS 
> 
> <quote> 
> BASIC-PLUS is an extended dialect of the BASIC programming language that 
> was developed by Digital Equipment Corporation (DEC) for use on its 
> RSTS/E time-sharing operating system for the PDP-11 series of 16-bit 
> minicomputers in the early 1970s through the 1980s. 
> 
> BASIC-PLUS was based on BASIC-8 for the TSS/8, itself based very closely 
> on the original Dartmouth BASIC. BASIC-PLUS added a number of new 
> structures, as well as features from JOSS concerning conditional 
> statements and formatting. In turn, BASIC-PLUS was the version on which 
> the original Microsoft BASIC was patterned. 
> 
> The language was later rewritten as a true compiler as BASIC-Plus-2, and 
> was ported to the VAX-11 platform as that machine's native BASIC 
> implementation. This version survived several platform changes, and is 
> today known as VSI BASIC for OpenVMS. 
> 
> ... 
> 
> Syntax and features 
> 
> BASIC-PLUS is patterned closely on later versions of Dartmouth BASIC, 
> including its powerful MAT commands. On top of this, DEC added a number 
> of unique flow-control structures. 
> 
> Line numbers were positive integers from 1 to 32767. 
> </quote> 
> 
> Again way before my time. 
> 
> Arne