.BDRO14 JSR BDlab19 ; Increment the music data pointer in BDdataptr1(1 0) ; and fetch the next music data byte into A STA SID+$18 ; Set SID register $18 to the music data byte we just ; fetched, which sets the volume and filter modes as ; follows: ; ; * Bits 0-3: volume (0 to 15) ; ; * Bit 4 set: enable the low-pass filter ; ; * Bit 5 set: enable the bandpass filter ; ; * Bit 6 set: enable the high-pass filter ; ; * Bit 7 set: disable voice 1 JSR BDlab19 ; Increment the music data pointer in BDdataptr1(1 0) ; and fetch the next music data byte into A STA SID+$17 ; Set SID register $17 to the music data byte we just ; fetched, which sets the filter control as follows: ; ; * Bit 0 set: voice 1 filtered ; ; * Bit 1 set: voice 2 filtered ; ; * Bit 2 set: voice 3 filtered ; ; * Bit 3 set: external voice filtered ; ; * Bits 4-7: filter resonance JSR BDlab19 ; Increment the music data pointer in BDdataptr1(1 0) ; and fetch the next music data byte into A STA SID+$16 ; Set SID register $16 to the music data byte we just ; fetched, which sets bits 3 to 10 of the filter cut-off ; frequency JMP BDskip1 ; Jump to BDskip1 to process the next nibble of music ; dataName: BDRO14 [Show more] Type: Subroutine Category: Sound Summary: Process music command <#14 vf fc cf> to set the volume and filter modes, filter control and filter cut-off frequencyContext: See this subroutine in context in the source code References: This subroutine is called as follows: * BDJMPTBH calls BDRO14 * BDJMPTBL calls BDRO14
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Subroutine BDlab19 (category: Sound)
Increment the music data pointer in BDdataptr1(1 0) and fetch the next data byte into A
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Configuration variable SID = $D400
Registers for the SID sound synthesis chip, which are memory-mapped to the 29 bytes from $D400 to $D41C (see page 461 of the Programmer's Reference Guide)