Assessments - 3, GPA: 4.7
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Each message is sent with a dummy leading timing byte of $00. If no MIDI PROGRAM CHANGES were received then nothing will be sent to the HOST until new data is sent to the MIDI IN of 16 the MPU-401. b. The MPU-401 will begin to increase its internal RECORD COUNTER. If it receives MIDI VOICE messages of any acceptable channels from MIDI IN it will send them to the HOST. Each message is sent with a leading timing byte which is calculated by the record counter based on the current TIME BASE of the MPU-401. The record counter will then be cleared. This means that the leading timing byte indicates the timing value from the last MIDI message which was sent to the HOST, to the message which the MPU-401 is now going to send. If no MIDI messages come for a long time, the MPU-401 will send an MPU MESSAGE $F8 (timing overflow) when the record counter reaches to 240 and the counter will be cleared. While recording: the HOST should read the exact number of bytes defined by the MPU-401 data format. (See section 3.) When the MPU-401 receives an ALL NOTES OFF message and all notes are OFF in that channel, it will not send any message to the HOST. However, if some notes are ON in the MIDI IN TABLE the MPU-401 will turn OFF these notes in the table and create NOTE OFF messages to send to the HOST, but the ALL NOTES OFF message itself will not be sent. Normally, any MODE messages such as OMNI ON / OFF, MONO, POLY are not passed to the HOST. However the command $35 will allow them to be passed. If the MPU-401 is set to MIDI SYNC mode with the $82 command it will begin recording at a tempo based on the incoming MIDI CLOCKS ($F8s). If the MPU-401 is in FSK sync mode, it will wait for an incoming tape sync tone from the TAPE IN jack. RECORD STAND-BY: The MPU-401 executes 'a' from above and then waits for another command which has a MIDI START or CONTINUE from the HOST, or if in REAL TIME AFFECTION : ON mode waits for a MIDI START ($FA) or CONTINUE ($FB) message from MIDI IN. : other command area. : no function. : STOP PLAYING: The MPU-401 will discontinue decreasing the play counters so that it will not request any additional track data. 17 It will transmit to the MIDI OUT port of the MPU-401 the NOTE OFF messages (with velocity zero) of the notes which have been turned on while in PLAY mode. The CHANNEL REFERENCE TABLES will be cleared. 1 0 : START PLAYING The MPU-401 will start to decrease the PLAY COUNTERS for all active tracks. If the counter reaches zero, it will transmit the MIDI message which has been received from the HOST to MIDI OUT. It will then send the MPU MESSAGE TRACK DATA REQUEST ($F0 - $F7) and will wait for the HOST to send the next MIDI data. The HOST should send the exact number of bytes defined by the MPU data format. (See section 3.) By clearing the PLAY COUNTERS ($B8) before the START PLAY, the MPU-401 will not transmit a MIDI message from the PLAY BUFFER at first, but will immediately send a TRACK DATA REQUEST to the HOST. This is the most typical sequence for START PLAY. When PLAY is stopped, the PLAY BUFFERS (timing and data) are not cleared so a PLAY CONTINUE can be possible. An ALL NOTES OFF message is created in the MPU-401 when all notes are turned OFF in the channel. 11 : no function. Bit 1 0 0 0 : no function. 0 1 : Transmits a MIDI STOP ($FC) to MIDI OUT. Resets DIN SYNC signal to low. Stops the FSK TONE modulation in TAPE OUT. (!) Saves METRONOME COUNTER, MEASURE END COUNTER and CLOCK TO HOST COUNTER for next CONTINUE PLAY. 1 0 : Transmits a MIDI START ($FA) to MIDI OUT. Resets DIN SYNC CLOCK. Sets DIN SYNC signal to high. Starts modulation of FSK TONE at TAPE OUT. (!) Clears METRONOME COUNTER, MEASURE END COUNTER and CLOCK TO HOST COUNTER. 1 1 : Transmits a MIDI CONTINUE ($FB) to MIDI OUT. Resets DIN CLOCK. Sets DIN SYNC signal to high. Starts modulation of FSK TONE at TAPE OUT. Sets DIN CONTINUE signal to high then reset to low. Restores METRONOME COUNTER, MEASURE END COUNTER and CLOCK TO HOST COUNTER. 18 This table shows each bit mapped possibility for the START, STOP, and CONTINUE commands of the MPU-401. COMMAND MIDI PLAY RECORD FUNCTION = = = = = = = = === = = = = ====== It It It II II II II II $00 _ _ _ Do Not Use $01 Stop - - $02 Start - - $03 Continue - - $04 - Stop - * $05 Stop Stop - STOP PLAY $06 Start Stop - $07 Continue Stop - $08 - Start - $09 Stop Start - * $0A Start Start - START PLAY * $0B Continue Start - CONTINUE PLAY $0C ~ $0F - - - Do Not Use $10 _ _ Stop ★ $11 Stop - Stop STOP RECORD $12 Start - Stop $13 Continue - Stop $14 - Stop Stop * $15 Stop Stop Stop Stop Over-Dub $16 Start Stop Stop $17 Continue Stop Stop $18 - Start Stop $19 Stop Start Stop $1A Start Start Stop $1B Continue Start Stop $1C - $1F - - - Do Not Use ★ $20 _ _ Stand-by RECORD STAND-BY ** $21 Stop - Stand-by * $22 Start - Start START RECORD * $23 Continue - Start C...