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Subject: 
Re: Perl rules!
Newsgroups: 
lugnet.off-topic.geek
Date: 
Thu, 22 Jul 1999 17:42:20 GMT
Viewed: 
1312 times
  
On Thu, 22 Jul 1999 16:11:41 GMT, "Don Heyse"
<donnell_heyse@adc.spam.go.away.com> wrote:

Perhaps you're right, but that jump instruction is relative to the Instruction
Pointer which uses a full register.  The segmented way you are relative
to a segment which only uses half a register.  You can take advantage of
this half register use for considerable savings.  Just don't ask me how cause
I forgot.

OK, at this point I'll have to take your word for it.  The segmented
address still seems like a high price to pay for a half-register.

There are other issues here.  4bits per pixel uses lookup tables to pick
colors.  You can do tricks with XORing colors to move things around without
redrawing everything.  I'm sure this was taken advantage of.  Perhaps this
is why moving the pieces with the keys seems so responsive.

Maybe this is the case in LEdit -- I don't have knowledge of that source
code.  But in LDraw, the graphics I/O is pretty simple - there are calls to
library routines to set the resolution, clear the screen, and write
individual pixels.  And I know the library supported higher-color modes.

Hey, does LEDIT support any resolution other than 640x480?

Nope.  WYSIWYG.[2]

Rats!

Good summary. :) :(

Steve



Message has 1 Reply:
  Re: Perl rules!
 
(...) I don't have source to LEdit either, but I used to write CAD software for a living around that time. We used all sorts of colormap manipulating tricks to speed up the rendering. These tricks just don't work in fixed color modes. You have to (...) (25 years ago, 22-Jul-99, to lugnet.off-topic.geek)

Message is in Reply To:
  Re: Perl rules!
 
(...) OK, relative-addressing mode is good. But it doesn't require segmented memory. All it requires is an instruction format with a defined result. For example, the conditional-jump instructions on the 6502 microprocessor[1] only used relative (...) (25 years ago, 22-Jul-99, to lugnet.off-topic.geek)

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