[Info-vax] The VMS terminal driver ( was: DCL and scripting)

[VAXman- at SendSpamHere.ORG]

In article <pursc2$mj4$1 at dont-email.me>, "Robert A. Brooks" <FIRST.LAST at vmssoftware.com> writes:
>On 12/12/2018 1:41 PM, Simon Clubley wrote:
>
>> I've never seen the VMS source code so I don't know the answer to
>> this, but is the terminal driver line editing code unmaintainable
>> because someone tried to be "clever" when writing the code and hence
>> caused maintainence problems later on when changes were required,
>> or was it simply that someone tried to fit something into the kernel
>> that should never have been placed in the kernel in the first place ?
>
>The terminal driver was the first to be written in the separated
>"class" and "port" driver model, where the higher layer protocols
>are in the class driver, and the port drivers contain hardware-specific
>stuff.  This was back in the VAX days, where you had an array of terminal
>muxes with varying hardware support control needs.  That separation was an
>attempt at making the class driver a bit more maintainable.  This model has been
>followed with other driver pairs, most notably the SCSI class driver DKDRIVER
>and the various SCSI and fibre channel port drivers below it.
>
>The terminal class driver is written in MACRO-32, and is a bit of a mess.
>
>I would think that t gives the host-based shadowing driver a run for its money 
>in terms of driving the Macro compiler nuts, although I've not heard Reagan
>complain about it, and he's quite capable of complaining about stuff.
>
>We are making some changes to the terminal class driver for X86, although those 
>changes are specific to the changes imposed by the X86 memory management model 
>that impact I/O.
>
>For those keeping score at home, there is no SVAPTE on X86, which is keeping
>our driver maintainers quite busy.

^^
@@

That's gonna make things interesting.  I can't wait to see this when it's all
available.  I'll be needing to make changes in my code too.
  
-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

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