Epson 6200A Network Card User Manual


 
S1C6200/6200A CORE CPU MANUAL EPSON 3
2 MEMORY AND OPERATIONS
2MEMORY AND OPERATIONS
A single-chip microcomputer using the S1C6200/6200A Core CPU has four major blocks: the
program memory (ROM), the data memory (RAM and I/O), the arithmetic logic unit (ALU) and the timing
generator circuit. This section describes each of these blocks in detail.
2.1 Program Memory (ROM)
Program memory contains the instructions that the CPU executes. Figure 2.1.1 shows the configuration of
the program memory.
Each instruction is a 12-bit word. Program memory can also be used for data tables for the table look-up
instructions.
There are two banks of program memory. Each bank is subdivided into 16 pages of 256 words (or steps).
That is:
Program memory = 2 banks
= 8,192 steps
1 bank = 4,096 steps
= 16 pages
1 page = 256 steps
1 step = 1 word
= 12 bits
Certain addresses in ROM have specific functions, as shown in Table 2.1.1.
Table 2.1.1 Allocated program memory
Bank 0, Page 1, Step 0
Bank 0, Page 1, Step 1 to 15
Bank 0, Page 0, Step 0 to 255
Bank 1, Page 1, Step 1 to 15
Bank 1, Page 0, Step 0 to 255
Address Function
Reset vector
Interrupt vectors used while a program is running in bank 0
Bank 0, page 0 area
Direct call subroutines for use by CALZ while a program is running in bank 0
Interrupt vectors used while a program is running in bank 1
Bank 1, page 0 area
Direct call subroutines for use by CALZ while a program is running in bank 1
Page 15Bank 0
Page 14Bank 0
Step 0
Step 1
Step 254
Step 255
Page 3Bank 0
Page 2Bank 0
Step 0
Page 1
Reset vector
Interrupt
vectors
for Bank 0
Bank 0
Step 0
Step 1
Step 15
Step 254
Step 255
Page 0Bank 0
Step 0
Step 1
Step 254
Step 255
Page 15Bank 1
Page 14Bank 1
Step 0
Step 1
Step 254
Step 255
Page 3Bank 1
Page 2Bank 1
Step 0
Bank 1
Step 0
Step 1
Step 15
Step 254
Step 255
Page 0Bank 1
Step 0
Step 1
Step 254
Step 255
PCB (between banks)
PCP
(within bank)
PCS
(within bank)
12-bit
instructions
Program or data
code area
Program or data
code or CALZ
subloutines in
Bank 0
Program or data
code or CALZ
subloutines in
Bank 1
Page 1
Interrupt
vectors
for Bank 1
Bank 0 Bank 1
Fig. 2.1.1 Program memory configuration