Inter-WIZ communications part II - page 4

For very efficient and rapid bus transfers, we can bypass the OS altogether and just take over the bus. With the OS's permission, of course.

For this we have the "send block direct" and "recv block direct" commands. These operate identically to the send/recv block, except all transfers are allowed to occur directly across the OS WIZ's data bus without any interference from the OS.

For example, if WIZ-1 had an analog-to-digital conversion (ADC) device behind one of its registers, and if WIZ-2 ran a fast Fourier transform algorithm (FFT) and had a hardware input buffer register which auto-increments through 1024 words, then if WIZ-1 did: 

   (send block direct, WIZ-2) , 1024 => ZOZ    // request to send 1024 words to WIZ-2
   1024 => repeat instruction ; ADC => ZOZ     // send ADC values, 1024 times

and if WIZ-2 did this:

   (recv block direct, WIZ-1) , 1024 => ZOZ    // request to recv 1024 words from WIZ-1
   1024 => repeat instruction ; ZOZ => buffer  // ZOZ => buffer, repeated 1024 times

then 1024 words would be copied across the OS WIZ's bus, from the ADC in WIZ1 to the buffer in WIZ-2.