Re: broken double hires

["Rick Kerman" <rkerman@mail.bright.net>]

Louis Schulman <louiss@gate.net> wrote in article
<52keot$fia@news.gate.net>...
 
> There seems to be something missing from your question.

The only thing missing is your comprehension.  Stephan wrote:

>> The orig. (small) Apple 80 col/64KB card is ok, I tested it with 
>> another _simple_ //e.

> I assume you are using some video card?  At least on my //e, the
> standard 80 col card and video port don't give you double hi-res,
> you need a video card.

Stephan has the EXTENDED 80 column card (pay attention).  The video
port WILL give you double hi-res, and you DO NOT need a video card.
Read the manual!

> Given that, have you tested the video card?  What kind of monitor are
> you using?  Have you tested that?
> 
> To directly answer your question, double hi-res is firmware that
> resides in the  video rom.  That does not seem to be a likely cause
> of this kind of problem.
<snipped rest of useless message>

Inadequte and misleading answer.  Double hi-res also involves hardware
switching which doubles the pixel clock rate and interleaves pixel data
from main and auxilliary memory banks.

I suppose it is possible for something to go wrong in the memory
management of the LSI chip, but I am always suspicious of "overnight"
problems.

Have you by any chance installed a RAM disk in auxilliary memory that
is stepping on the graphics memory area?