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from Ekeeda Hello friends in this video
we will study various addressing modes
in the 80-85 in the last video we have
already started the programming model of
80-85 now before moving towards the
instructions say it first we need to
understand this instruction falls into
some categories of addressing group so
what are those addressing group that we
will study in this video addressing
modes gets classified into five types
number one is contest implied addressing
in this type generally the operand is
not specified and your operand is
accumulative for example C M a now if
you'll see this instruction CL a is your
opcode and generally after our code we
write the operon but in the instruction
but if your instruction is without of
course sorry if your instruction is
without operator then those instructions
comes under the category of implied
addressing mode so implied in the in
this type generally operand is not
specified within instruction and your
operand is accumulated see this CMAC ma
means what complement accumulator swear
operandi generally accumulator which we
called it as implied addressing mode the
next we have is direct addressing mode
in the direct addressing mode the
address appears after opcode of
instruction in a program memory for an
example say this instruction LD a nine
xxx H now LD a nine triple F H means for
after your opcode nine propel F H is an
address so after of course directly
address is given so such type of
instruction comes under category of a
direct addressing mode the instruction
using direct addressing mode are
generally of three byte for an example
see this Lda will take one bite whereas
this address is of two bytes so
altogether it will be of three byte
instruction next we have is registered
addressing mode in the register
pressing more your source operands a
general purpose register for an example
when we transfer data from one register
to another register so in that case your
source operand is normally a register so
all those instructions comes under the
category of register addressing mode so
they are single by instruction for
example just now I give an example move
a comma B in the move a comma B your
content of B will go to a so here your
source operand is generally one general
purpose register next we have is
immediate addressing mode in the
immediate addressing mode the data
appears immediately after the opcode of
instruction for an example say this ad
is 0 5 now a di 0 5 mins for a after I
mean after your opcode directly your
data comes in the instruction so here
what you will do you will add your 0 5
with the accumulator so the data is not
in any register the data is directly
specified so such type of instructions
comes under the category of immediate
addressing mode they can be the two byte
or three bite of instruction next we
have is register indirect addressing
mode in this the content of register
pair points to address of operant the
register pair HL is specified for
addressing 16-bit address of memory
location so for an example whenever
memory comes like you know add an atom
means what you are adding your memory
content with the accumulator and memory
points to which pair HMF so register
pair actually specified for addressing
16-bit address of memory location so all
such type of instructions comes under
the category of register indirect
addressing mode so how they have
summarized it the content of register
pair points to address of operant your
content of register pair they will point
to where they will point to address of
operant so they come under the category
of what register addressing register
indirect addressing mode so let us have
a recap of this number one we have is
implied addressing mode in the implant
addressing mode generally your operand
is not specified and your operand is
generally accumulator for an example cma
Odyssey
see all those instruction comes under
the category of what implied addressing
mode where the operand is not specified
on your code is given then you will at
it I mean if only opcode is given then
from that you can easily identify it
okay this instruction is under the
category of or implied addressing mode
then we have directive direct addressing
mode in the direct addressing mode the
address comes immediately after the
opcode of the instruction for an example
LD a sta with such kind of instruction
they come into the category of direct
addressing would you just have to see if
the address is coming immediately after
the of course then we called it as what
direct addressing mode next we saw was
registered addressing mode in the
register addressing mode here source
operands are generally what registers I
mean they are general purpose register
so all those instructions they come
under the category of what register
addressing mode
immediate addressing mode in immediate
addressing mode your data appears
immediately after the instruction then
we called it as what immediate
addressing mode say whenever with the
instruction I comes like you know env I
Adi SBI then all those category of
instruction that comes under the
category of immediate addressing mode
because in that data appears immediately
as courier of course and the last we
have is called as register indirect
addressing mode in this the content of
register there points to address of
operant for an example and so these are
all types of addressing group here all
instruction comes under any one of this
addressing mode so I hope you have
understood the addressing modes of 80-85
in the next video we will study the data
transfer thanks for watching this video
thank you
you
