Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!olivea!oliveb!amiga!boing!dale
From: dale@boing.UUCP (Dale Luck)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Simple Frame Buffer boards
Message-ID: <918@boing.UUCP>
Date: 1 Dec 90 21:29:50 GMT
References: <916@boing.UUCP> <23699@grebyn.com>
Reply-To: dale@boing.UUCP (Dale Luck)
Organization: Boing, Milpitas, Ca.
Lines: 36

In article <23699@grebyn.com> ckp@grebyn.UUCP (Checkpoint Technologies) writes:
>In article <916@boing.UUCP> dale@boing.UUCP (Dale Luck) writes:
>>Why is it so difficult to design a simple memory
>>mapped frame buffer board. I've gotten the specs
>>on a couple, like the firecracker and most seem
>>to have forgotten that the main cpu of the Amiga
>>is 68000 based. Read: FLAT ADDRESS SPACE.
>
>The 8 meg expansion address space of the Amiga is too precious  to
>devote a meg or more of it to "just" a frame buffer.

I think the benefit far out weighs the cost.
I'd be glad to give up 1/8 of my
address space for a 1024x1024x8 frame buffer board. I think
it is a very small price to pay. I just don't see that many
people unwilling to give up 1M-2M of memory. It still leaves
4-6 megs of memory for programs as well as the 1M of chip memory.

I expect there are a lot of machines out there (A2500 like) that
are basically 1M chip, 4M on the 030/030 board and no other
memory board in the system. One reason for this is my programs
slow down terribly when they dig into the 16bit ram. So the address
space is wasted in this case. Actually a whole 4M is wasted. Boy
would I like a 24bit 1kx1k color card, that would fit in quite nicely.

I did not realize that SO MANY were running with fully blown out
(8M of ram) systems that use all of it up the last 1-2M during
normal program execution.

Besides which the VRAM is still real ram, and you get some real
interesting patterns on the display when using it as regular ram
and compiling with Lattice. ;-)

-- 
Dale Luck     GfxBase/Boing, Inc.
{uunet!cbmvax|pyramid}!amiga!boing!dale