The generic 8031 architecture sports a Harvard architecture, which contains two separate buses for both program and data. So, it has two distinctive memory spaces of 64K X 8 size for both program and data. It is based on an 8 bit central processing unit with an 8 bit Accumulator and another 8 bit B register as main processing blocks. Other portions of the architecture include few 8 bit and 16 bit registers and 8 bit memory locations.
Each 8031 device has some amount of data RAM built in the device for internal processing. This area is used for stack operations and temporary storage of data.
This base architecture is supported with onchip peripheral functions like I/O ports, timers/counters,versatile serial communication port. So it is clear that this 8031 architecture was designed to cater many real time embedded needs.The following list gives the features of the 8031 architecture:

8031單片機是Intel公司生產的MCS-51系列單片機中的一種，除無片內ROM外，其余特性與MCS-51單片機基本一樣。

??? MCS-51單片機的引腳描述及片外總線結構

??? 一、芯片的引腳描述

??? HMOS制造工藝的MCS-51單片機都采用40引腳的直插封裝（DIP方式），制造工藝為CHMOS的80C51/80C31芯片除采用DIP封裝方式外，還采用方型封裝工藝，引腳排列如圖。其中方型封裝的CHMOS芯片有44只引腳，但其中4只引腳（標有NC的引腳1、12、23、34）是不使用的。在以后的討論中，除有特殊說明以外，所述內容皆適用于CHMOS芯片。