Differences

This shows you the differences between two versions of the page.

--- music_processor [2016/05/23 01:21]
ex_writer [MUZCPU Instruction Set]
+++ — (current)
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-====== Music Processor ======
-The music processor can be thought of as an independent CPU handling all output to the music/noise ports. The MUZCPU has 4 registers:
-| MPC | Like all program counters, points to the next data byte to fetch. |
-| MSP | Like a stack pointer, points to return addresses on the stack. |
-| DURATION | Loaded at the start of a note, then decremented every 60th of a second. |
-| VOICES | A status register that tells which voices (tones) to load with what data. |
-The voices status register is shown below. Execution proceeds right-to-left. Make sure that you always have at least one PC incrementing bit or load on.
-{{vs_register.png}}
-[NM:56]
-===== Music System Routines =====
-^ Name ^ Description ^
-| [[music processor#bmusic|BMUSIC]] | Begin playing music |
-| [[music processor#emusic|EMUSIC]] | Stop music |
-===== Music System Routine Descriptions =====
-==== BMUSIC ====
-BEGIN PLAYING MUSIC
-| Calling Sequence: | <code z80>SYSTEM    BMUSIC</code> or <code z80>SYSSUK    BMUSIC
-DW        (music stack)
-DB        (voices byte)
-DW        (score)</code>|
-| Arguments: | A = voices to start with\\ HL = music program counter (score)\\ IX = music stack pointer |
-| Notes: | None |
-| Description: | Quiets any previous music, then interprets specified "score." |
-| Restrictions: | None |
-==== EMUSIC ====
-STOP MUSIC
-| Calling Sequence: | <code z80>SYSTEM    EMUSIC</code> or <code z80>SYSSUK    EMUSIC</code>|
-| Arguments: | None |
-| Notes: | None |
-| Description: | Outputs 0 to volume ports and halt music processor. |
-| Restrictions: | None |
-===== MUZCPU Instruction Set =====
-^ # OF BYTES ^ MNEMONIC ^ COMMENT ^
-| 2 | VOICES,(data) | VOICES=(data) |
-| 2 | MASTER,(data) | TONE0=(data) |
-| 3 | CALL,(address) | (SP)=(PC+3) PC=address |
-| 1 | RET | PC=(SP++) |
-| 3 | JP,(address) | PC=address |
-| 2 | NOTE1 | Duration, note or data (D1) |
-| 3 | NOTE2 | Duration, D1,D2 |
-| 4 | NOTE3 | Duration, D1,D2,D3 |
-| 5 | NOTE4 | Duration, D1,D2,D3,D4 |
-| 6 | NOTE5 | Duration, D1,D2,D3,D4,D5 |
-| 2 | REST | Duration in 60ths of a second\\ Pauses silently (except during LEGATO) |
-| 1 | QUIET | Stops music and sets volume=0 |
-| 2 | OUTPUT | Port #, Data |
-| 9 | OUTPUT | SNDBX,DATA10,D11,D12,D13,D14,D15,D16,D17 |
-| 3 | VOLUME | (VOLAB),(VOLMC) sets volume for notes |
-| 1 | PUSHN | Push # between 1-16 onto the stack |
-| 1 | CREL | Call relative to next instruction |
-| 3 | DSJNZ | Decrement stack top and jump if not 0, else pop stack |
-| 1 | LEGSTA | Flips between STACATO and LEGATO modes\\ STACATO is clipped 1/60th before the end of each note\\ LEGATO allows one note to run into the next |
-Note: All durations are limited to a maximum of 127
-[NM:57]
-===== Music Score Example =====
-<code z80>
-          VOICES     11010100B     ;ABC=Data 1
-          MASTER     0A1H          ;ABC=1/2
-          VOLUME     88H,08H
-          NOTE1      12,A1
-          NOTE1      12,C2
-          NOTE1      24,E2
-          NOTE1      12,C2
-          NOTE1      12,E2
-          REST       6
-          VOICES     11110110B     ;Suck in Vibrato, AB and C bytes
-          NOTE3      12,14,A2,E2
-          QUIET
-</code>
-[NM:58]