This paper shows how well established control system techniques can be introduced to formulate guidelines for clinical testing and measurement of the HIV/AIDS disease for the estimation of HIV/AIDS parameters. It is assumed that the viral load and CD4 plus T cell count in plasma blood are measured. The objective is to estimate all parameters in the basic three dimensional HIV/AIDS model. For this purpose, through an observability analysis, the minimal number of measurement samples for the CD4 plus T cell and the viral load counts is first obtained. The paper determines then the HIV progression stages when an estimation of all parameters is impossible. Outside these stages, the paper proposes two online estimation algorithms for all HIV parameters based on the well known techniques of adaptive identifers and adaptive observers. Conditions for parameter convergence are discussed. Simulation results are demonstrated for the parameter estimation using adaptive observers.