DEC VT05 with OS/8 -- basic system rebuild?

[Philipp Hachtmann]

Good morning,

> First, the BUILD.SV utility is both a tool to change the OS 
> configuration and a record of the configuration. Typically, BUILD.SV 
> will contain the original configuration of the system. Changes are made 
> by RUNing and then SAVEing new versions of the configuration.
Yes, that's well known on my side. It also seems to contain the LOADed device handlers.


  > The following is a transcript of taking a system configuration saved in
> BLDDMO.SV and adding a non-system TD8E handler. I will insert comments 
> with a #.
> 
...
> # in the configuration.
> $BOOTSTRAP
> SYS BUILT

That's pretty not what I wanted to do (gave up the idea running VT05 at >300 baud). I know to use 
BUILD. The point is elsewhere.

> Thats all there is to it.
No. There is more. There's ALWAYS more *g*

The console TTY is handled by the OS/8 keyboard handler *directly*. So it does NOT use one of the 
handlers installed with BUILD.
BUILD itself seems to contain the LOADed handlers. When you enter BOOT (or BOOTSTRAP), BUILD writes 
out OS/8 and the configured handlers to the specified system device. The specified system device can 
be clean before. That proves that BUILD really puts all the OS/8 stuff onto the disk/DECTape.

How is the system INITIALLY built? There are *some* explanations in the OS/8 handbook, involving 
some obscure paper tapes and BUILD. But no really detailed description.
It would be nice to be able to compile OS/8 itself.


> A TTY handler will already be present, so that will have to be removed 
> before it can be replaced. DELETE removes the handler from the 
> configuration. UNLOAD completely deletes the handler from the BUILD image.
Yes, yes, yes. BUT: The TTY handler is only responsible for the TTY: device used for things like 
DIRECT and other software using handlers.
The keyboard monitor does not use TTY:!

I gave up the idea patching the KBM to generate fill characters: a) I'm not sure if I would be able 
to insert even one instruction into the KBM code (it's written TIGHT!), b) There are too many other 
programs using direct I/O. They all would have to be patched as well (FORTRAN IV RTS as an easy 
example).

> The OS/8 Handbook is your friend. Start at page 2-34.
Only at the first glance :-(

Best wishes,

Philipp

-- 
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