TMS370 datasheet(7/43 Pages) TI

7 / 43 page

TMS370Cx32

8-BIT MICROCONTROLLER

SPNS015C – FEBRUARY 1990 – REVISED FEBRUARY 1997

POST OFFICE BOX 1443

• HOUSTON, TEXAS 77251–1443

central processing unit (CPU) (continued)

The ST, status-bit notation, and status-bit definitions are shown in Table 3.

Table 3. Status Registers

IE2

IE1

Reserved

RW-0

R = read, W = write, 0 = value after reset

program counter (PC)

The contents of the PC point to the memory location of the next instruction to be executed. The PC consists

of two 8-bit registers in the CPU: the program counter high (PCH) and program counter low (PCL). These

registers contain the most significant byte (MSbyte) and least significant byte (LSbyte) of a 16-bit address.

During reset, the contents of the reset vector (7FFEh, 7FFFh) are loaded into the PC. The PCH (MSbyte of the

PC) is loaded with the contents of memory location 7FFEh, and the PCL (LSbyte of the PC) is loaded with the

contents of memory location 7FFFh. Figure 2 shows this operation using an example value of 6000h as the

contents of the reset vector.

Memory

Program Counter (PC)

PCH

PCL

0000h

7FFEh

7FFFh

Figure 2. Program Counter After Reset

memory map

The TMS370Cx32 architecture is based on the Von Neuman architecture, where the program memory and data

memory share a common address space. All peripheral input / output is memory mapped in this same common

address space. As shown in Figure 3, the TMS370Cx32 provides memory-mapped RAM, ROM, EPROM, data

EEPROM, I / O pins, peripheral functions, and system-interrupt vectors.

The peripheral file contains all I / O port control, peripheral status and control, EEPROM, EPROM, and

system-wide control functions. The peripheral file is located between 1000h to 107Fh and is divided logically

into eight peripheral file frames of 16 bytes each. The eight PF frames consist of five control frames and three

reserved frames.Each on-chip peripheral is assigned to a separate frame through which peripheral control and

data information is passed.

TMS370 Datasheet(PDF) 7 Page - Texas Instruments