[TUHS] Tandem NSK implementation language (was: Happy birthday, John Backus!)

[Paul Winalski]

On 12/4/18, Greg 'groggy' Lehey <grog at lemis.com> wrote:
> On Tuesday,  4 December 2018 at 15:59:46 -0500, Paul Winalski wrote:
>>
>> I forgot one:  Tandem NonStop OS on Alpha, which was under development
>> at Compaq at the time that Compaq decided to sell off the Alpha
>> technology to Intel.
>
> Was this a start-from-scratch operation?  The original Tandem OS
> (called Guardian at the time) was written in Tandem's TAL (Transaction
> Application Language, amongst other productions), a vague evolution of
> HP's SPL that looked more like Algol, starting in about 1974.  That is
> also the earliest I know of an operating system being implemented
> entirely in a high level language.

No, not start-from-scratch.  They modified the existing MIPS TAL front
end to generate GEM intermediate language.  I don't know if the TAL
front end generated GEM IL directly or if they wrote some sort of
IL-to-IL translator wedge.  IIRC we didn't need to do any object file
work in GEM to support Tandem because they were already using an
object file format we supported (ELF or COFF).

> When Tandem started using other architectures (MIPS) in the late 1980s
> we discussed translating the whole thing to C.  I was asked to write a
> 99% translator (maintaining comments and such), and failed.

IIRC some of the Tandem code was in C at this point (1999) but a TAL
for Alpha was also needed.

-Paul W.