{ ALTON PRILLAMAN HOWEVER, now would be a good time to learn about "Bitwise Operators" to accomplish your goal With minimal memory requirements. I'll start With the basics (no offense intended). You may have heard, or remember from a Programming class that a Byte is made up of 8 bits. When looking at a Byte in binary, each bit holds a value of 0 or 1 that when put together in their respective places will add up to make the number. Here's an example of a Byte: B I N A R Y T A B L E ========================================================================= Power | 7 6 5 4 3 2 1 0 | of 2 ------+---------------------------------+----- Bit # | 8 7 6 5 4 3 2 1 | ------+---------------------------------+----- Value | 128 64 32 16 8 4 2 1 | HEX ------+---------------------------------+----- 0 | 0 0 0 0 0 0 0 0 | $00 1 | 0 0 0 0 0 0 0 1 | $01 * 2 | 0 0 0 0 0 0 1 0 | $02 3 | 0 0 0 0 0 0 1 1 | $03 * 4 | 0 0 0 0 0 1 0 0 | $04 5 | 0 0 0 0 0 1 0 1 | $05 6 | 0 0 0 0 0 1 1 0 | $06 7 | 0 0 0 0 0 1 1 1 | $07 * 8 | 0 0 0 0 1 0 0 0 | $08 9 | 0 0 0 0 1 0 0 1 | $09 10 | 0 0 0 0 1 0 1 0 | $0A 11 | 0 0 0 0 1 0 1 1 | $0B 12 | 0 0 0 0 1 1 0 0 | $0C 13 | 0 0 0 0 1 1 0 1 | $0D 14 | 0 0 0 0 1 1 1 0 | $0E 15 | 0 0 0 0 1 1 1 1 | $0F * 16 | 0 0 0 1 0 0 0 0 | $10 | | * 32 | 0 0 1 0 0 0 0 0 | $20 * 64 | 0 1 0 0 0 0 0 0 | $40 * 128 | 1 0 0 0 0 0 0 0 | $80 | | 255 | 1 1 1 1 1 1 1 1 | $FF ------+---------------------------------+----- * = All columns to the right had filled up With 1s, so we carried to the next column to the left. Notice that when all of the "bit places" have a "1" in them, that the total adds up to be 255 which is the maximum number that a Byte can hold. In binary (the inner part of the Chart), "1" is the maximum value a bit can hold Until it carries to the next column to the left. This brings us to the next Chart, HEXIDECIMAL: H E X I D E C I M A L T A B L E ========================================================================= Power| 1 0 |of 16 Power| 1 0 |of 16 -------+---------+----- -------+---------+----- Decimal| | Decimal| | Value| 16 0 | HEX Value| 16 0 | HEX -------+---------+----- -------+---------+----- 0| 0 0 | $00 31| 1 1 | $1F 1| 0 1 | $01 * 32| 2 0 | $20 2| 0 2 | $02 33| 2 1 | $21 3| 0 3 | $03 | | 4| 0 4 | $04 47| 2 F | $2F 5| 0 5 | $05 * 48| 3 0 | $30 6| 0 6 | $06 63| 3 F | $3F 7| 0 7 | $07 * 64| 4 0 | $40 8| 0 8 | $08 79| 4 F | $4F 9| 0 9 | $09 80| 5 0 | $50 10| 0 A | $0A 95| 5 F | $5F 11| 0 B | $0B * 96| 6 0 | $60 12| 0 C | $0C 111| 6 F | $6F 13| 0 D | $0D * 112| 7 0 | $70 14| 0 E | $0E 127| 7 F | $7F 15| 0 F | $0F * 128| 8 0 | $80 * 16| 1 0 | $10 255| F F | $FF 17| 1 1 | $11 * 256| |$0100 -------+---------+----- -------+---------+----- * = All columns to the right had filled up With 15 (F) so we carried to the next column to the left. The hexidecimal table is derived from BASE 16. The value that each column may hold a value of 15 (F) before we carry to the next column. Also notice that when both columns fill up With a value of "F" ($FF) that the result is 255, which is the maximum For a Byte. Okay, With that behind us, let's take a look at your application. As you may have noticed in the binary table in the previous message, a Byte will give us the ability to track up to 8 bits. Our goal here is to turn on or off each of the 8 bits as each channel is turned on or off. I assume that you've got 16 channels to work With, so we'll use a Word instead of a Byte. When looked at in binary, a Word is like placing two Bytes side-by-side. Notice that the HEXIDECIMAL works the same way. 256-------------------------+ +---------------------------- 128 512----------------------+ | | +------------------------- 64 1024-------------------+ | | | | +---------------------- 32 2048----------------+ | | | | | | +------------------- 16 4096-------------+ | | | | | | | | +---------------- 8 8192----------+ | | | | | | | | | | +------------- 4 16384-------+ | | | | | | | | | | | | +---------- 2 32768----+ | | | | | | | | | | | | | | +------- 1 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Power | 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0|of 2 -------+------------------------------------------------+------- Bit # | 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1| -------+------------------------------------------------+------- Decimal| | Value| BINARY | HEX -------+------------------------------------------------+------- 1| 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1| $0001 2| 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0| $0002 4| 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0| $0004 8| 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0| $0008 16| 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0| $0010 32| 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0| $0020 64| 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0| $0040 128| 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0| $0080 256| 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0| $0100 512| 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0| $0200 1024| 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0| $0400 2048| 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0| $0800 4096| 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0| $1000 8192| 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0| $2000 16384| 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0| $4000 32768| 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0| $8000 -------+------------------------------------------------+------- Though it has taken us a While to get here, you now have a "value" for each of your midi channels. if you need to use more than 16 channels, you can use the same methods applied above using a LongInt to give you a total of 32 channels (or bits). You can now declare these as Constants in your Program like so: } Program MidiStuff; Const {Midi Channels} Ch1 = $0001; Ch2 = $0002; Ch3 = $0004; Ch4 = $0008; Ch5 = $0010; Ch6 = $0020; Ch7 = $0040; Ch8 = $0080; Ch9 = $0100; Ch10 = $0200; Ch11 = $0400; Ch12 = $0800; Ch13 = $1000; Ch14 = $2000; Ch15 = $4000; Ch16 = $8000; Var MidiChannels : Word; { Now you can turn on or off each channel and check to see if one is set by using the following Procedures and Functions. You can accomplish this by using the or and and operators. } Function ChannelIsOn(Ch : Word) : Boolean; begin ChannelIsOn := (MidiChannels and Ch = Ch); end; Procedure TurnOnChannel(Ch : Word); begin MidiChannels := MidiChannels or Ch; end; Procedure TurnOffChannel(Ch : Word); begin MidiChannels := MidiChannels and not Ch; end; begin MidiChannels := $0000; {Initialize MidiChannels - No channels on!} TurnOnChannel(Ch2); if ChannelIsOn(Ch2) then Writeln('Channel 2 is on!') else Writeln('Channel 2 is off!'); if ChannelIsOn(Ch3) then Writeln('Channel 3 is on!') else Writeln('Channel 3 is off!'); TurnOnChannel(Ch16); TurnOnChannel(Ch10); TurnOffChannel(Ch2); if ChannelIsOn(Ch2) then Writeln('Channel 2 is on!') else Writeln('Channel 2 is off!'); end.