2 program memory (rom), Toshiba – Toshiba TMP87CP24AF User Manual
Page 7
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TOSHIBA
TMP87CM24A/P24A
1.2 Program Memory (ROM)
The TMP87CM24A has a 32Kx8-bit (addresses
8000
h
to FFFF
h
), and the TMP87CP24A has a 48Kx8-bit
(addresses
4000
h
to FFFF
h
) of program memory (mask programmed ROM).
Addresses FFOO
h
to FFFF
h
in the program memory can also be used for special purposes.
(1)
Interrupt/Reset vector table (addresses FFEO
h
to FFFF
h
)
This
table
consists
of
a
reset
vector
and
15
interrupt
vectors
(2
bytes/vector).
These
vectors
store
a
reset start address and interrupt service routine entry addresses.
(2)
Vector table for vector call instructions (addresses FFCO
h
to FFDF
h
)
This
table
stores
call
vectors
(subroutine
entry
address,
2
bytes/vector)
for
the
vector
call
instructions
[CALLV
n].
There
are
16
vectors.
The
CALLV
instruction
increases
memory
efficiency
when
utilized
for frequently used subroutine calls (called from 3 or more locations).
(3)
Entry area (addresses FFOO
h
to FFFF
h
) for page call instructions
This
is
the
subroutine
entry
address
area
for
the
page
call
instructions
[CALLP
n].
Addresses
FFOO
h
-
FFBF
h
are normally used because address FFCO
h
to FFFF
h
are used for the vector tables.
Programs and fixed data are stored in the program memory. The instruction to be executed next is read
from the address indicated by the current contents of the program counter (PC). There are relative jump
and absolute jump instructions. The concepts of page or bank boundaries are not used in the program
memory concerning any jump instruction.
Example:
The relationship between the
jump instructions and the PC.
© 5-bit PC-relative jump [JRS cc, $ + 2+d]
E8C4H: JRS T, $ + 2 + 08H
WhenJF
=
1,thejump
ismadeto
E8CE
h
,
which is
08
h
added to the contents of the
PC.
(The
PC
contains
the
address
of
the
instruction
being
executed+
2;
therefore,
in
this
case,
the
PC
contents
are
E8C4
h
+ 2 = E8C6
h
.)
@ 8-bit PC-relative jump [JR cc, $ + 2+d]
E8C4H : JR Z, $ + 2 + 80H
When ZF = 1, the jump is made to
E846
h
,
which is
FF80
h
(-128) added to the
current contents of the PC.
(3)
16-bitabsolute jump [JP a]
E8C4H : JP 0C235H
An
unconditional
jump
is
made
to
address
C235
h
-
The
absolute
jump
instruction
can
jump
anywhere
within
the entire 64-Kbyte space.
Address
4000
h
(8000)
FFOO
FF7B
FFBF
FFCO
FFC1
FFC2
FFDF
FFEO
FFE1
FFE2
FFFD
FFFE
FFFF
call vector (L)
call vector (H)
interrupt vector (L)
interrupt vector (H)
reset vector (L)
reset vector (H)
ROM
contents
Example :
The relationship
between ROM Contents
and Call group
instructions/Interrupt/
Reset
CALLP 7BH
PC<-FF7B
56
C8
CALLV OH ; PC<-C856
h
68
D3
3E
CO
INT5
PC D368
RESET
PC<-C03E
Figure 1-2. Program Memory Map
In theTLCS-870 Series, the same instruction used to access the data memory (e.g. [LD A, (HL)]) is also used
to
read
out
fixed
data
(ROM
data)
stored
in
the
program
memory.
The
register-offset
PC-relative
addressing
(PC
+
A)
instructions
can
also
be
used,
and
the
code
conversion,
table
look-up
and
n-way
multiple jump processing can easily be programmed.
3
-
24-7
2002
-
10-03