Path: utzoo!attcan!uunet!super!udel!rochester!cornell!mailrus!ames!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga
Subject: Re: Memory and the A2024 Hedley monitor.
Keywords: Solder to silicon?  Do us a favor!
Message-ID: <2729@amiga.UUCP>
Date: 7 Aug 88 22:46:17 GMT
References: <3627@louie.udel.EDU> <540@ncar.ucar.edu>
Reply-To: jimm@cloyd.UUCP (Jim Mackraz)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 135

In article <540@ncar.ucar.edu> hull@hao.UCAR.EDU (Howard Hull) writes:
)>First.  Can you have a screen (say workbench (and thusly CLI's etc))
)>that is 1024 by 800, and then have other screens behind it
)>that are 640 by 200 or 640 by 400, and use screen to front
)>and back gadgets to flip between these things?

)A screen is a screen is a screen.  The screen flipping key will flip the
)screens ok unless the Amiga software people put in some tests and locks
)to prevent it.

Right.  All features and mode changes are free unless we put code in
to disable it.  Software is easy.   ;^)

It turns out that the depth arrangment works with the new A2024 modes,
but you can't drag down a Hedley screen nor drag down a normal screen
to expose a Hedley screen ('Hedley' is a technical term for reconstituted
bitplanes).

)Why would they do that, you no doubt ask?  Probably because the 640 by 200
)screens would be poorly proportioned and would look like crap,

Wrongo, and you are now a nominee for the "Speaks Beyond Whereof He Knows"
awards.

)and they don't want to show people crap. 

Well, you do have a few redeeming positions ...

)They are trying to sell Amiga computers,
)not give them a poor reputation.  The effect would be very similar to the
)effect you get when you show a 320 by 200 window on a 320 by 400 screen -
)squashed fonts, flicker, circles turned into ellipses, font strokes thinned
)to where you can't see them, etc.

More like when you show a 200 line screen in interlaced modes: vertically
there is a scan-doubling.  On the A2024, there is another factor of
two around somewhere.

)In one detail I am not sure what they'll do,

Just this one, eh ... ?

)that is, whether or not the Amiga programmers would put in something to
)expand the 640 to the width of the 1024 screen (it is 1024 wide (conventional
)w x h description), right?) or just run pixels into the blitter starting at
                                                         ^^^^^^^
					    dreaming, now ....

)the left side and going until there were no more pixels left in memory for
)that line, with screen background "color" filling in the rest of the line.

Turns out the hardware guys handle scan conversion, and happily so,
since the software would not have a chance.

)I think this latter one is what they'd have to do,
)and that's why I think it would come out like crap. 

Wrongo, twice.

)You will note that the only reason they can
)get away with creating 320 x 200 screens pulled down in front of 640 x 400
)screens (and they have to go to interlace on both sreens, even so) is that
)the pixel count is _exactly_ twice for the interlaced hi-res screen - and
)that's something the electronics can handle in hardware with a divide-by-two
)binary counter. 

The confusion here between vertical and horizontal tricks is significant. 
The vertical direction is simpler.  The horizontal is due to Hedley, who
apparently uses a little more than a divide-by-two counter, as your
observation would indicate.

)They don't do so well with dividing by 1.6 [though it would
)be a trivial matter to design a divide by 1.6 hardware counter for the task
)of synchronizing the Amiga blitter, but non-trivial to get it installed in
)1E6 already existing computers in peoples' offices, homes, and closets. :-) ]

God bless that Hedley.

)>and thus have one mongo big screen, and then have other
)>applications running in the 640 by 200 screens???
)As pointed out by others on the net, you have to have a lot of blitter
)address space - but it would be possible to do this.

It will be common.

)>Second questions:
)>Have any of the genuiuses with the RFANG's  (REALLY Fat Agnus)
)>figured out a hack to get 1 meg of chip
)>ram into the Amiga 1000?????
)>PLEASE PLEASE ?
)There are probably not very many hardware types that have RFANGs.  Even those
)that do have them are busy with other stuff.  When Amiga went from the regular
)Agnus to the fat Agnus, they did essentially the same thing Intel/IBM did when
)they went from the 8088 to the 80186.  They took some of the surrounding MSI
)(Medium Scale Integration, i.e. MC7400) logic and integrated it onto the LSI
)(Large Scale Integration, i.e. MC68881) die.  That means that the wires you
)need to solder to don't exist anymore, but rather are now little tiny silicon
)etchings on the die inside Fat Agnus.  Now they could have exactly transported
)the outside logic to inside so that the new FA pins would exactly correspond
)to existing PC traces on some of the logic somewhat removed from the FA, but
)remember that designers like to change things and are always interested in

... those crazy designers ...

)improving the stuff they did before, taking advantage of certain economies
)in the new packaging.  The result in the case of the Amiga is not only no
)correspondence between the new Fat Agnus pin names and functions and old A1000
)printed circuit traces, but also no place where they particularly agree with
)points in the remotely located circuits, either.  Of course this implies that
)they changed the detailed nature (not necessarily the function, though) of the
)surrounding logic packages when they replaced the A1000 logic with the A2000
)logic.

Kind of runs on, but with my limited understanding of the hardware, this
sounds like a reasonable explanation.  I wouldn't advise anyone quoting
from the technical content of this message, though.

)And if you are good at this last one, how good are you at finding
)a sharp lawyer for when CA sues you for "look and feel"?

... nor the business aspects.

)						Howard Hull

I dunno Howard, your attempt at explanation and guesses are OK, but you're
pretty inaccurate.  Please forgive my good-natured needling.  But I
suggest people think back if you post a description of the features of 
the Enhanced Chip Set in the future.

	jimm
-- 
	Jim Mackraz, I and I Computing	  
	amiga!jimm	BIX:jmackraz
Opinions are my own.  Comments regarding the Amiga operating system, and
all others, are not to be taken as Commodore official policy.