Click above to get retro games delivered to your door ever month!

      The TMS320C2x supports direct memory access (DMA) to its local (off-
      chip) program, data, and I/O spaces. Two signals,
      ____     _____
      HOLD and HOLDA, are provided to allow another device to take control
                                                 ____
      of the processor's buses. Upon receiving a HOLD signal from an
      external device, the processor acknowledges by bringing
      _____
      HOLDA low. The processor then places its address and data buses as
                                  __  __  __    _      ____
      well as all contol signals (PS, DS, IS, R/W, and STRB) in the high-
      impedance state. The serial port output pins, DX and FSX, are not

      affected by HOLD. Signaling between the external processor and the
      TMS320C2x can be performed using interrupts.

      If the TMS320C2x is in the middle of a multi-cycle instruction, it
      will finish the instruction before entering the hold state. After
      the instruction is completed, the buses are placed in the high-
      impedance state. This also applies to instructions that become
      multi-cycle due to the insertion of wait states or due to the use
      of RPT/RPTK instructions.
            ____
      After HOLD is de-asserted, program execution resumes from the same
      point at which it was halted. HOLDA is removed synchronously with
      HOLD. If the setup time is met, two machine cycles are required
      before the buses and control cycles become valid.
      ____
      HOLD is not treated as an interrupt. If the TMS320C2x were executing
      the IDLE instruction before entering the hold state, it resumes
      executing IDLE once it leaves the hold state.

      The hold function on the TMS320C25 has two distinct operating modes:
            A TMS32020-like mode, in which execution is suspended, and
            A TMS320C25 concurrent DMA mode, in which the TMS320C25
            continues to execute its program while operating from internal
            RAM or ROM, thus greatly increasing throughput of data-
            intensive applications.