Introduction
The 8044 integrates a powerful 8051 microcontroller with an intelligent serial communications controller, providing a single-chip solution for effectively implementing distributed processing or distributed control systems. The microcontroller is a self-sufficient unit containing ROM, RAM, an ALU, and its own peripherals. The 8044 shares the same architecture and instruction set as the 8051, replacing the 8051's serial interface with an intelligent SDLC/HDLC Serial Interface Unit (SIU) and adding 64 bytes of RAM to the 8051's RAM array. The SIU supports bit rates up to 2.4 Mbps and operates concurrently with the microcontroller without any throughput loss to either unit. Due to the SIU's built-in intelligence, the CPU is relieved of many communication tasks, freeing more processing power for controlling local peripherals or external processes. The microcontroller is a standalone, high-performance single-chip computer suited for complex real-time applications such as instrumentation, industrial control, and intelligent computer peripherals. Key features include an 8-bit CPU, on-chip oscillator, 4K bytes of ROM, 192 bytes of RAM, 32 I/O lines, 64K external data memory address space, 64K external program memory address space, two fully programmable 16-bit timer/counters, a five-source interrupt structure with two priority levels, and bit-addressable capability for Boolean processing. 60% of instructions execute in 1 μs, 40% execute in 2 μs, and 8×8-bit unsigned multiply/divide completes in 4 μs. The internal data memory is the most functionally flexible address space, subdivided into a 256-byte internal data RAM address space and a 128-bit special function register address space. The 8044 provides 32 general-purpose I/O lines organized into four groups of eight lines each, designated Port 0, Port 1, Port 2, and Port 3.
