VisibleZ: A Mainframe Architecture Emulator for Computing Education

Abstract

This paper describes a PC-based mainframe computer emulator
called VisibleZ and its use in teaching mainframe Computer Organization
and Assembly Programming classes.

VisibleZ models IBM’s z/Architecture
and allows direct interpretation of mainframe assembly language object
code in a graphical user interface environment that was developed in Java.

The VisibleZ emulator acts as an interactive visualization tool to simulate
enterprise computer architecture. The provided architectural components
include main storage, CPU, registers, Program Status Word (PSW), and
I/O Channels. Particular attention is given to providing visual clues to
the user by color-coding screen components, machine instruction execution,
and animation of the machine architecture components.

Students interact with VisibleZ by executing machine instructions in a step-by-step
mode, simultaneously observing the contents of memory, registers, and changes in
the PSW during the fetch-decode-execute machine instruction cycle. The
object-oriented design and implementation of VisibleZ allows students to
develop their own instruction semantics by coding Java for existing specific
z/Architecture machine instructions or design and implement new machine
instructions.

The use of VisibleZ in lectures, labs, and assignments is described
in the paper and supported by a website that hosts an extensive
collection of related materials. VisibleZ has been proven a useful tool in
mainframe Assembly Language Programming and Computer Organization
classes. Using VisibleZ, students develop a better understanding of
mainframe concepts, components, and how the mainframe computer works.

ACM Computing Classification System (1998): C.0, K.3.2.