In 1983 Tandy introduced Model 12 as an upgrade for model II. The 12, compared to model II has half-heigth double sided 8-inch 1.2MByte floppy disk drives, and most of the Model II electronics was integrated onto a single main board. The Video and Keyboard card now plugged into a single slot on the main circuit board. There was an optional expansion card cage that allowed for six more expansion cards. The white phosphor CRT of the Model II was replaced with a green CRT, which made working with the Model 12 easier on the eyes.

The TRS Model 12 is essentially a Model 16B, but without the extra Motorola 68000 processor. However Tandy provided an upgrade kit with the processor and the extra memory, so that the Model 12 could be upgraded to a full model 16B.

The Graphics of this machine stood out for the time, the base model only supported text mode with up to 80 columns, but Tandy's graphics card provided a high resolution monochrome mode of 640x240 pixels. The card came with the Graphics version of Microsoft BASIC on floppy disk which included new graphics commands, as well as PEEK and POKE commands.

The Z80 quickly became popular in the personal computer market, with many early personal computers, such as the TRS-80 and Sinclair ZX80, using the Z80 as their central processing unit (CPU). It was also widely used in home computers, such as the MSX range, SORD, and the Amstrad CPC, as well as in many arcade games. Additionally, it was also used in other applications such as industrial control systems, and embedded systems. The Z80 was widely used until the mid-1980s, when it was gradually replaced by newer microprocessors such as the Intel 80286 and the Motorola 68000.

The Z80 microprocessor was developed by Zilog, a company founded by Federico Faggin in 1974. The Z80 was released in July 1976, as a successor to the Intel 8080. It was designed to be fully compatible with the 8080, but also included new features such as an improved instruction set, more powerful interrupts, and a more sophisticated memory management system.

The Z80 quickly became popular in the personal computer market, with many early personal computers, such as the TRS-80 and Sinclair ZX80, using the Z80 as their central processing unit (CPU). It was also widely used in home computers, such as the MSX range, SORD, and the Amstrad CPC, as well as in many arcade games. Additionally, it was also used in other applications such as industrial control systems, and embedded systems. The Z80 was widely used until the mid-1980s, when it was gradually replaced by newer microprocessors such as the Intel 80286 and the Motorola 68000. The design was licensed to Synertek and Mostek as well as the European SGS.

The Z80s instruction set is binary compatible with the Intel 8080, so that 8080 code such as the CP/M Operating System and Intel's PL/M compiler for the 8080 can run unmodified on the Z80. The Z80 had many enhancements over the 8080 such as 16-bit data movement instructions, block copy and block I/O instructions, single bit addressing of all registers, IX/IY offset registers, better interrupt system and a complete duplicate register file for context switching during an interrupt.