CPU8 Plus 2.10

CPU8Plus serves as an enhanced version of the original CPU8 App, primarily expanding the memory capacity for programs utilized within this compact 8-bit computing environment.

This tool effectively educates users on the internal workings of computers, utilizing a straightforward instruction set consisting of just 16 commands. The architecture includes an 8-bit bus, two 8-bit registers, an 8-bit Arithmetic Logic Unit (ALU), and an 8-bit storage word. However, it is limited by a 4-bit addressing scheme, encompassing only a 4-bit Program Counter and a 4-bit Address Register, which restricts addressable memory space to a mere 16 bytes (or words).

With the introduction of CPU8Plus, the addressing capacity has significantly expanded through an upgraded 8-bit Program Counter and Address Register, increasing the addressable memory to 256 bytes (or words)—a substantial improvement representing a 16-fold increase over the original CPU8.

This upgrade allows for more sophisticated instruction handling; the microcode now distinguishes between one-word and two-word instructions while appropriately advancing the Program Counter. The operand space has also been enhanced, doubling in size from 4 bits to 8 bits.

The updated CPU8Plus model reflects these modifications, with its assembler generating new executable object code accordingly. Notably, this is achieved without sacrificing source code compatibility—users can seamlessly transfer their existing CPU8 source code into CPU8Plus files, allowing for immediate assembly and execution with no additional alterations required.

As a result of these upgrades, programming complexity can increase substantially, enabling users to create programs that are now capable of being 16 times larger in scope.

The accompanying documentation has been improved to provide historical context and clarity. Progress displays have shifted to hexadecimal representation, enhancing usability over the previously cumbersome binary format. Additionally, a dedicated “memory” display has been implemented to showcase the full range of the expanded 256 bytes.

This platform appears well-suited for varied educational contexts including classroom environments, independent study initiatives, or simply for users seeking an engaging way to explore computer functionality in a hands-on manner. Notably, it ensures that no individual user information is accessed during use.