KIT OFFER & Re: hardware solution for direct access to video ram

[Brian D. Botton]

In article <586 at uncle.UUCP> jbm at uncle.UUCP (John B. Milton) writes:
>In article <2575 at laidbak.UUCP> botton at laidbak.UUCP (Brian D. Botton) writes:
>...
>>JOHN: Why didn't you try a software (loadable device driver) approach?
>I was refering to an everything in the driver aproach, where access would still
>be fast, but your point is well taken. It is wonderful to be able to work on
>drivers the way we can on this machine, but it's still a bitch next to regular
>user level programs. The idea is begining to grow on me, which does bring up a
		      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>bit of a delema as far as how I'm going to implement the screen part of the
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>X server.
 ^^^^^^^^^

  Glad to hear it, hope it's contagious :-).  Yeah, user level code is SOOOOO
much nicer to deug.

  I have received a number of e-letters saying that they found the idea
interesting, but since they weren't hardware hackers they were reluctant to
give it a try.  I want to reiterate, this daughter board makes NO modifications
to ANY boards on the 3B1/7300.  This was the single most important design goal.
  One person thought my original posting said I was reluctant to program pals,
and to be honest I was a little (okay, very) vague.  I wanted to see what kind
of response this generated before I started making offers.  I posted those long
instructions just in case someone wanted to go ahead and give it a try, even if
they haven't built a pc board before.  Plus, I feal that everyone should know
what's involved in making a custom pc board.  Don't let it scare you away, it
just takes time and patience.

  So, what does this boil down to?  Brad's and mine (mostly Brad's) port of Mgr
is going to rely on this little board, so if you are thinking of using Mgr
you'de better give this board a bit of serious thought.  Well, X people, if
John is thinking this over, what do you think?  If there was enough interest I
would be willing to put together a kit that includes all the parts that would
be needed.  And because I understand that the initial investment to buy all the
junk needed to etch one little board is pretty high, I am willing to investigate
a commercially etched pc board.  It seems to me that if widely supported ports
of Mgr and X are to succeed it will have to be easy to get this board.  What
will this cost? I haven't the slightest idea, but probably in the $30 - $50
range.  I'll do some checking around to find out what pc board manufacturing
costs are going for in the Naperville (Chicago far west suburb) area.  I should
also be able to simplify the design with a commercial board, such as a single
sided pc board and no 64 pin socket, and thus keep the cost down.

  I know there are people working on X at this time and I would hate to see a
lot of effort lost because of a change in midstream.  I'll start checking
tomorrow and try to post some cost figures within a couple of days.  In the
mean time, send me e-mail if you are interested.  If there are enough people in
on this to even come close to breaking even I'll go ahead with providing kits,
pal, pc board, and instructions included.  If we're lucky it might be done in
less than a month.

>
>>	8.  I don't know if I should mention this, but I don't see any reason
>>	    to hide it.  The displayable portion of the video does not use up
>>	    all of the video ram.  So we also have an automatic shared memory
>>	    segment at the end of video ram.  BUT, it is wide open and you're
>>	    probably a fool to use it and an idiot to rely on it.
>
>I WAS hoping you wouldn't (mention) it, but it is 32768-31320=1448 bytes...
 ^^^^^^^^^^^^^^^^^^^^^^^^^

  Yeah, I know, I debated for a while about that one.  But figured we're all
adults and what we do in the privacy of our own computer . . .
Besides, I DO keep your process's grubby little mits from mucking with the
disk controllers, OBM, page tables . . . 

-- 
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   _][_n_n___i_i ________		Brian D. Botton
  (____________I I______I		laidbak!botton
  /ooOOOO OOOOoo  oo oooo