!!! Linear screen area addressing
ZXNet echo conference «real.speccy»
From Ruslan Abdullaev → To All 19 June 2004
Let's assume, hypothetically, that we have access to screen mode with
the following addressing.
H L
110ccccc yyyyyyyy
where c is the column number in familiar places (0-31)
y is the line number in pixels (0-191)
or, if we draw an analogy with standard addressing, this will
look like this:
H L
110ccccc ssrrrlll
where c is the column number in familiar places (0-31)
s - segment number (0-2)
r - row number (0-7)
l - line number (0-7)
What is the advantage of such addressing:
- transition to the next familiar place is carried out incrementing the high
byte, one line below - increasing the low byte. Such addressing
combines the advantages of standard and linear addressing, while
addressing is linear not by columns, but by lines.
#с000,#с100,#с200,...,#df00
#с001,#с101,#с201,...,#df01
..........................
#с0bf,#с1bf,#с2bf,...,#dfbf
- elementary calculation of the address specified both in familiar places and in
pixels.
- the size of the screen area will increase slightly, 8192 bytes, while
only 6144 bytes are used, the maximum possible resolution
with such addressing is 512*256 (64x256)
So, now let's forget the word "hypothetically", and think about how all
this can be implemented.
ra.id'mayhem
--
Subject to mail @mail.ru - http://talk.mail.ru