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Amiga Collections: MegaDisc
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MegaDisc 36 (1993-11)(MegaDisc Digital Publishing)(AU)(Disk 2 of 2).zip
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MegaDisc 36 (1993-11)(MegaDisc Digital Publishing)(AU)(Disk 2 of 2).adf
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Music_&_MIDI
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MIDI_Math
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MIDI_Math
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Text File
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1993-10-20
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3KB
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62 lines
MIDI MATH:
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Computers communicate using numbers and prefer to keep it
really simple by using only 2 numbers or digits;0 or 1, we call
this BINARY. This differs from the numbers we are all used to 0
to 9, we call this decimal. The disadvantage with us using binary
notation is that the numbers get very large eg. 255 dec. becomes
11111111 bin. You can see that what is an advantage to the
computer in using only 2 digits becomes a disadvantage to humans
as the numbers can become pretty big.
In MIDI we only need to know the numbers 0 to 255 dec. This
is where a 3rd form of numerical expression comes in. Hexadecimal
(16) notation is used because it allows large numbers to be
expressed using relatively few symbols. Hex. uses the numerals 0
to 9 as well as the letters A to F so that we count
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,10, etc. Hence 255 dec. becomes
11111111 bin or FF hex. Pretty simple eh!
The chart MIDIFORMATTABLE1 (Textfile) or MIDIFORMATTABLE.IFF
(graphic) will hopefully make things much clearer by showing the
relationship between BINARY, DECIMAL and HEXADECIMAL.
Print out this chart (it'll fit on an A4 page) and hold it
sideways. Right side to the top. Look at all the columns of
binary numbers, use a rule across what is now the width of the
page and you should start to see something in its graphical
representation that is very interesting. It gives an insight into
the logic of computers using binary notation.
The MIDI spec. only uses these numbers.
The last line of the table "00111111", each digit is 1 byte,
the "0" on the left is the Most significant byte (MSB) and the "1"
on the right is the Least Significant byte (LSB), all 8 bits make
1 byte. If a bit is the smallest piece of data then you can see
that 8 bits make a byte. 1 byte makes a word and 4 words is
called a 4 byte longword.
"0" (Bin) = Bit = Most Significant Bit
"00111111" (Bin) = 8 bits = 1 Byte = Word = "63" (DEC) = "3F" (HEX)
"F03F3340" (HEX) = 4 Bytes = 4 Byte Longword
"F03F3340 44546434 CDFA3290 54231323" = 16 Bytes
With this simple comparison you should be able to see that the
benefits to Hex notation is of great importance in the
understanding of MIDI data. For this reason I intend to spend 1
whole article on Binary , Decimal and Hexadecimal notation and how
it specifically relates to MIDI. The advantage is of course that
all computer notation follows these patterns.
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