title: Memory Traces: Recursive Engrams
author: MD, Ida Pearce
description: Ida Pearce, M.D. received her medical degree at the Royal College of Surgeons on England, with a Diplomate in Ophthalmology in 1951. She completed clinical studies at Moorfields and the Royal Eye Hospital in London. During the 1970s, she was involved with glaucoma research at UCLA and the Veterans Administration Hospital in Long Beach, California. The majority of her career has been spent as a practicing ophthalmologist, with a private practice in Long Beach, California, and at Kaiser Permanente Medical Group, Department of Ophthalmology in Bellflower, California, where she was a partner for over thirty years. Dr. Pearce can be contacted at ipearce@visualmemoryresearch.org.
zlib_text:  4 
  Solutions
  Solution 4.1
  4.1.1 The values of the signals are as follows:
  RegWrite
  MemRead
  ALUMux
  MemWrite
  ALUOp
  RegMux
  Branch
  a.
  1
  0
  0 (Reg)
  0
  Add
  1 (ALU)
  0
  b.
  1
  1
  1 (Imm)
  0
  Add
  1 (Mem)
  0
  ALUMux is the control signal that controls the Mux at the ALU input, 0 (Reg) 
  selects the output of the register ﬁ le and 1 (Imm) selects the immediate from the 
  instruction word as the second input to the ALU.
  RegMux is the control signal that controls the Mux at the Data input to the regis-
  ter ﬁ le, 0 (ALU) selects the output of the ALU and 1 (Mem) selects the output of 
  memory.
  A value of X is a “don’t care” (does not matter if signal is 0 or 1)
  4.1.2 Resources performing a useful function for this instruction are:
  a.
  All except Data Memory and branch Add unit
  b.
  All except branch Add unit and second read port of the Registers
  4.1.3 
  Outputs that are not used
  No outputs
  a. 
  Branch Add
  Data Memory
  b. 
  Branch Add, second read port of Registers
  None (all units produce outputs)
  4.1.4 One long path f