On Fri, 13 Feb 1998, Ben Ketcham wrote:

> | Jacob H. Suter wrote:
> |   Ragge has mentioned that, at least on the MicroVAX II, the ROM character
> | output routines only work with the MMU turned off.  Someone (Bertram?) talked
> | about a hack to disable the MMU, print a character, and turn it back on again.
> | I don't know how far that got.
> 
> ???  Does this mean that a MicroVAX II, running Ultrix or VMS, cannot
> operate in text mode on the console after the OS has started?  Seems
> crazy, but in all honesty, I've only seen MicroVAXen running in graphics
> mode (X11) after bootup (my own have no monitors, serial terminals only).

No it doesn't.  A MicroVAX II can run in text mode on the console after
they've loaded the OS.  VMS and 4.3BSD both do it.  I'm pretty sure that
VMS doesn't use the ROM routines.  I don't know about 4.3BSD.

However, the console isn't too great.  X is more useful and generally
faster.  It's a graphical workstation and not a PC.  The text mode was
probably intended for just setting up the system.

|  Boris Gjenero <bgjenero@undergrad.math.uwaterloo.ca>              |
|  Home page:  http://www.undergrad.math.uwaterloo.ca/~bgjenero/     |
|  "Luke, you're going to find that many of the truths we cling to   |
|  depend greatly on our own point of view." - Obi-Wan Kenobi, ROTJ  |



> Surely, *if* the ROM contents were mirrored to RAM, which would seem to be
> the way to do it anyway (don't want a sluggish console like Suns have,
> yuck!), access to the particular fixed addresses necessary to hit the console
> display could be mediated by a device driver, in the usual Unix way?
> Perhaps the MMU would have to be turned off once at startup, to read the
> ROMs?
> 
> What, exactly, do the ROM routines do, anyway?  If one could just access
> the raw bitmap of the display, perhaps one could generate ones own
> characters without using the ROM routines, mirrored or not?  This type
> of access will be needed for the eventual X server anyway...
> 
> --ben
>