Digital Signal Processors

• General-purpose CPU versus specialized processing units
• Why?
  • signal processing

Convolution filter

FIR

Discrete Fourier transform

Discrete cosine transform (JPEG, MPEG, …)

Common operations?

• ADD?
• MULtiply?
• MAC -> Multiply Accumulate

General-purpose vs. specialized

• Thunderbolt is a plane built around gatling gun

• DSP is a chip built around MAC unit

  • multiplier
  • adder
  • accumulator

TMS32010

• One of 25 most influential chips in human history
  • First OpAmp, 555, CCD, Intel DRAM, MOS 6502, Z80, Intel 8088
• Texas Instruments
• 1982
• Add. Multiply, MAC
• All blocks can run in parallel
• Saturation arithmetic

TMS32010 internals

• ROM/EPROM 1536 kwords
• RAM 144 kwords
• Stack 4x12 bits
• ALU + 32bit accumulator
• Barrel shifter
• Fast multiplier 16b x 16b -> 32b

TMS32010 registers

• No general purpose registers!
• Accumulator 32bit
• PC 12bit
• DP 1bit as bank register
• ARP 1bit selects AR0 or AR1 for addressing
• AR0 + AR1 (16b) for addressing
• T (16b) + P (32b) registers are connected to multiplier
  • T: temporary
  • P: product

Addressing

• Addressing
  • auto increment
  • auto decrement
  • shift by x bites (arrays of different types)
  • change AR0 <-> AR1 for next operation

More advanced DSPs

Saturation arithmetic