In this current year, the integration of technology in learning and assessment has become a major need in education. Computers and related technologies are powerful tools for addressing new challenges in the creation and application of assessment methods beyond conventional practices and facilitate the recording of cognitive skills and knowledge of test participants. One technology product in the assessment is CBT (Computer Based Testing), which is an innovative approach in assessment capable of displaying problems and correcting them quickly and easily. In Indonesia, CBT has been used as a computer-based national examination system (UNBK), a computerized exam as a media to display the problem and process of answering it. In addition, Digital Assessment Bloom research is a form of tool development a computer-based assessment for the 9th grade of SMP based on Bloom's revised taxonomy.This study is aimed at: (1) understanding the characteristics of Digital Assessment Bloom test items using the Item Response Theory and (2) determining the student’s ability on the trial exam instruments. This research uses quantitative approach assisted with SPSS and BILOGMG 3.0 software. The developed DAB has been piloted on a limited scale in two junior high schools selected by random sampling technique. The result obtained is that the DAB instrument has fulfilled the assumptions on the item response theory and in accordance with the 3-Parameter Logistics model. Furthermore, the result of the item classification indicates that there are 16 good items which are stored in the DAB item bank for the development of the purpose of the assessment used. In addition, DAB is also able to describe students' mathematical skills well.