[Info-vax] OS Ancestry

[Henry Crun]

On 15/03/2022 12:32, ni... at desmith.net wrote:
> 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

Story goes:

Programmer entered a BASIC program
1! PROGRAM NAME
32767 end

and could then report to his manager:
"Program is ready, just a few lines missing in the middle..."



-- 
Mike R.
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