7220 Datasheet, PDF (35/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.2 Access area
2.2 Access area
The ROM, RAM and various I/O control registers are assigned within the same memory area. Therefore, the
same instructions are used for data transfers and arithmetic operations without making any distinction
between memory and I/O.
Since the program counter is a 16-bit register, 64 K-byte memory area can be accessed: from addresses
as 000016 to FFFF16.
The first 256 bytes of the 64 K-byte memory area are called the “zero page” and the last 256 bytes are
called the “special page.” These areas can be accessed with only 2 bytes by using each special addressing
mode.
M37220M3-XXXSP/FP
Refer to “CHAPTER 4. M37220M3-XXXSP/FP.”
RAM
(384 bytes)
for
M37221M6
RAM
(320 bytes)
for
M37221M4
CRT display RAM
(96 bytes)
(See note)
ROM
(24 K bytes)
for
M37221M6
ROM
(16 K bytes)
for
M37221M4
000016
Internal RAM
00C016
SFR area
Special function register
00FF16 ^{(Refer to Figures 2. 3. 3 and 2. 3. 4)}
017F16
01BF16
Internal RAM
Not used
CRT display ROM ^1000016
(8 K bytes)
Zero page
11FFF16
060016
06B716
RAM
for display
A00016
Not used
C00016
Internal ROM
: Internal ROM area for
program counter
ROM
for display
Not used
FF0016
FFDE16
Interrupt vector area
FFFF16
Special page
1FFFF16
Note: Refer to Table 2.11.4 Contents of CRT display RAM.
Fig. 2.2.1 Access area of M37221M4-XXXSP and M37221M6-XXXSP/FP
2-8
7220 Group User’s Manual