Problems for Learning Technology
8085 ASSEMBLY LANGUAGE PROGRAMMING
1.Write a program,
which loads registers, A, B, C and D with an identical
constant [e.g.$C0]. Try to optimize the program in such a way
that the smallest number of program bytes is used. Test the
program in single-step mode. After each step test, the
register (s) of interest.
2.Assume that 3 bytes of data
are stored at consecutive memory addresses of the data-memory
starting at Y. Write a program which loads register C with
(Y), i.e. with data contained at memory address Y, D with
(Y+1), E with (Y+2) and A with (Y+1).
indirect addressing, and
(ii)Use direct addressing mode
(LDA instruction), and
Compare (i) and (ii) in terms of
3.Test the above 3 programs at the
end of each single step. Choose Y within an address of RAM
available as per result of the memory map experiment
4. Assume that 2 bytes of data are stored at the
consecutive addresses of data-memory starting at address Z.
Use indirect addressing i.e. addresses Z', Z'' and Z'''
specified by 3 register pairs DE and BC and HL. Write a
program which moves the data from addresses Z and Z+1 to
addresses Z' and Z'+1, then to addresses Z" and Z"+1,and then
to address Z''' and Z'''+1.
Test the program by executing
it using GO command, and then by checking at the data-memory
addresses, Z', Z'+1 Z'', Z''+1, Z''' and Z'''+1.
Assume that 1 byte of data is stored at a data-memory address
Q. Write a program which tests bit 3 of (Q)[i.e. 4th bit from
lsb], write ÿ into a memory address Q+5, if bit 3 = '0', and
write $00 at the same address in case bit 5 = '1'. Test the
program, during execution itself in run-mode.
program which tests if any bit is '0' in a data byte specified
at an address R. If it is so, $00 would be stored at address
R+1 and if not so then $FF should be stored at the same
address. We test the program in run-mode.
program, which test if the all-odd bits are '1' in a data byte
at a data-memory location S. If it is so store $01 at S+1,
else stores $00 at the same location.
of data are specified at consecutive data-memory locations
starting at Z. Write a program which increments the value of
all sixteen bytes by $01.
9. Two data-bytes are stored
at addresses Y and Y+1. Interchange the data bytes at these
two addresses using (i) indirect addressing and (ii) direct
addressing. Execute the two programs and get the identical
results. Also find the difference in memory space used by
these two programs.
10.Eight bytes (unsigned binary
numbers) with upper nibble zero in each byte are stored at
consecutive data-memory address starting Q. Compute the sum of
the eight bytes and store it at an address Z. Use indirect
11.Two unsigned binary numbers are stored
at consecutive data memory addresses X, X+1.
program for computing (X+1) - (X) by using only the ADD
instruction. The magnitude of the result should be stored at
register C and the sign at D, ($00 if positive and $01 if
negative) D using the 2's complement concept.
double precision number (i.e. a 16 bit unsigned number) is
stored at Z and Z+1 (lower byte at X). Another double
precision number is stored at Z' and Z'+1. Add the two numbers
and store result at Z'' and Z''+1 and double this number and
store the result at Z''' and Z'''+1.
precision number (i.e. a 16 bit unsigned number) is stored at
Z and Z+1 (lower byte at X). Another double precision number
is stored at Z' and Z'+1. Subtract the two numbers and store
the result at ZIV and ZIV+1.
14.Two 2-digit BCD
numbers, each less than 128 decimal, are stored at the two
consecutive memory addresses, Q and Q+1. Write a program for
computing the sum and storing the result at address Q+2 using
a decimal adjust instruction.
15.Two 2-digit BCD
numbers are stored at consecutive memory addresses, Q+3 and
Q+4. Compute the difference of the two numbers and store the
result at location Y. Use decimal subtraction with the aid of
DAA and 1's complement.
16.(i) Two-digit BCD number is
stored at memory address X. Convert the number into binary and
store the result at an address Q.(ii) An 8-bit binary number
is stored at data memory location Y. Convert it into decimal
(BCD) and store the result of the address Q.
program which decrements a counter (i.e. a binary number
stored at register C) one by one and halts when the counter
value is zero. Test the program in single-step. Again modify
the program, which increments the contents of C up to decimal
18. A counter can be defined as a register, a
register pair or a memory address whose content gets
incremented or decremented. Define such a counter as
subroutine. Write a program for the generation of 2 different
time-delays using the same subroutine. Implement this program
by using following steps: (i) Set initial value for delay
1[=input parameter of subroutine], (ii) Call subroutine named
count, (iii) Set initial value for delay-2, (iv) Call counter
subroutine, (v) Jump to step( i).
Set the counter to a
small initial value and test the program in a single-step
19. Assume crystal frequency = 6MHz. Implement a
time-delay loop (counter) for the generation of a 50ms delay.
Using monitor delay routine at an address $0559 and described
in section VIII.6.
20. Assume crystal frequency = 4MHz.
Implement a time-delay loop (counter) for the generation of a
60s delay. Using monitor delay routine at an address $0559 and
described in section VIII.6. Test this program with the help
of your wristwatch by inserting a RST0 instruction such that
the program transfers (its control) to the monitor after
execution of the time-delay in order to display of initial
boot message after 60s.
21. A binary number less than
decimal 25 is stored at memory address X. Multiply the number
by 6 and store the result at X+1.
22. Now multiply by
10 using a formula: X. 10 = X. 2 + X. 23, and using a concept
that a multiplication by 2 corresponds to a shift left by one
23.Write a program for a decimal counter (00-99),
which is programmable for the clock-frequency (e.g. frequency
can be specified as 6MHz or 4MHz at memory address Q) and
display the count in the data-field using a corresponding
24.Same as problem No. 23 but let
the counter count from decimal 00 to a given decimal number
(stored at a data-memory) where it gets reset and starts
25. S binary numbers are stored at consecutive
data-memory addresses starting at Y, where S is defined at a
memory address Z. Find the largest number and store the result
at address Z'.
26. S binary numbers are stored at
consecutive data memory addresses starting at Q. Rearrange the
numbers in ascending order.
27.Write a program for
moving a Data-block of 100 bytes. Assume starting address of
source block at $0000 and destination is from memory address
28. N bytes start from address Q. These are to
be moved to address Q+N+1. The addresses for Q and N are
specified at address X.
29. Given two integer numbers
stored at memory locations Q and Q+1. Write a program for
displaying the greatest common factor (GCF).
the given conditions of problem at serial number 22 above,
write a program to divide a number by 10 (instead of
multiply). Assume that the number is in multiple of 10,and is
less than 251.
31.A binary number is stored at
data-memory location Q+5. Compute the number of its logical
1's and store the result at Q+6.
32. In computer
communication, data bits are often transmitted in ASCII
(abbreviation for American Code for Information Interchange)
format. This code consists of 128 symbols for numbers, letters
and signs, out of which the hexadecimal characters have the
representations as given in table VIII.6. Assume that a
hex-decimal character is stored in its ASCII code at address
Z. Store the corresponding character at another address at
33. A code word is stored at data-memory location
X. Write a program for testing whether the code word belongs
to the ASCII code for decimal 0. Set address to $FF if YES and
$00 if NO. [Refer table for ASCII code.]
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