LRQn high duration 15940ns 24203ns 41600ns
SBY low duration (....allophone length....)
[[File:SP0256 ALD Detail.png]]
* From the Z80 perspective, the stuff with 180..210ns timings reacts immediately.
* However, the LRQ high duration of 15..41us is visible to the Z80 (though any well programmed / existing Z80 software should not rely RELY on the presence of this delay) (it should of course be able DEAL with it, ie. it should not send new allophones while LRQ is high) (caution: The SSA-1 detection in "Roland in Space" DOES rely on the presence of that delay).
* Theoretically, in standby state, the chip could process incoming data immediately, so LRQ wouldn't need to go HIGH at all. The fact that it does go HIGH may have two reasons: First, the chip may be unable to react immediately. Second, it may be done intentionally, for use with edge-triggered IRQ or DMA hardware.
* min/avg/max = Timings measured on real hardware (Amstrad SSA-1)
The min/avg/max values are slightly higher than the calculated values. This is probably because the SP0256 executes "NOPs" (with repeat=1 and pitch=unchanged) while in standby mode, and refuses to start a new allophone until it has finished the "NOP".
[[File:SP0256 SBY Duration.png]]
num name spec calc min avg max
3E /EL/ 190.0 136.5 138.22 139.21 140.52
3F /BB2/ 50.0 50.2 51.92 53.17 54.10
[[Category:Hardware]]