ARM is abbrevated as advanced risc machine.
This generation introduced the Thumb 16-bit instruction set providing improved code density compared to previous designs. The most widely used ARM7 designs implement the ARMv4T architecture, but some implement ARMv3 or ARMv5TEJ. All these designs use a Von Neumann architecture, thus the few versions comprising a cache do not separate data and instruction caches.
Some ARM7 cores are obsolete. One historically significant model, the ARM7D is notable for having introduced JTAG based on-chip debugging; the preceding ARM6 cores did not support it. The "D" represented a JTAG TAP for debugging; the "I" denoted an ICEBreaker debug module supporting hardware breakpoints and watchpoints, and letting the system be stalled for debugging. Subsequent cores included and enhanced this support.
It is a versatile processor designed for mobile devices and other low power electronics. This processor architecture is capable of up to 130 MIPS on a typical 0.13 µm process. The ARM7TDMI processor core implements ARM architecture v4T. The processor supports both 32-bit and 16-bit instructions via the ARM and Thumb instruction sets.
ARM licenses the processor to various semiconductor companies, which design full chips based on the ARM processor architecture.
The original ARM7 was based on the earlier ARM6 design and used the same ARMv3 instruction set. The ARM710 variant was used in a CPU module for the Acorn Risc PC, and the first ARM based System on a Chip designs ARM7100 and ARM7500 used this core.
The ARM7TDMI (ARM7+16 bit Thumb+j tag Debug+fast Multiplier+enhanced ICE) processor is a 32-bit RISC CPU designed by ARM, and licensed for manufacture by an array of semiconductor companies. In 2009 it remains one of the most widely used ARM cores, and is found in numerous deeply embedded system designs. Texas Instruments licensed the ARM7TDMI, which was designed into theNokia 6110. The ARM7TDMI-S variant is the synthesizable core.
The ARM7EJ is a version of the ARM7 implementing the ARMv5TE instruction set originally introduced with the more powerful ARM9E core.
HERE related pdf of the arm7 lpc2148(which i prefered for learning basics)