1. MICROFRIEND
DYNA – 85
User’s Manual
Kailas Vaibhav , G– Wing , 3rd Floor, Park Site,
Vikhroli ( West ) , Mumbai – 400 079 . INDIA
Tel . : 91 - 22 - 5181900 (16 Lines)
Fax . : 91 - 22 - 5181930 / 5181940
s a l e s @ d y n a l o g i n d i a . c o m
w w w . d y n a l o g i n d i a . c o m

2. TABLE OF CONTENTS
PAGE NO.
INTRODUCTION
INTRODUCTON TO MICROFRIEND DYNA-85 1
CHAPTER 1
CONFIGURATION OF MICROFRIEND DYNA-85 1.1
1.1 SYSTEM OVERVIEW……………………………………… 1-1
1.1.1 SYSTEM HARDWARE CONFIGURATION……. 1-1
CENTRAL PROCESSING UNIT………………… 1-1
MEMORY…………………………………………. 1-1
HEX KEYPAD/DISPLAY INTERFACE…………. 1-2
8279 DATA FORMAT……………………………. 1-2
PARALLEL I/O/ INTERFACE…………………… 1-3
SERIAL I/O AND AUDIO CASSETE INTERFACE.1-3
TIMER………………………………………………. 1-3
EXPANSION SLOT………………………………… 1-4
1.1.2 SYSTEM COMMANDS OVERVIEW…………….. 1-4
1.1.3 SYSTEM FIRMWARE OVERVIEW……………… 1-5
1.1.4 APPLICATON OF MICROFRIEND DYNA-85…… 1-6
CHAPTER 2
SYSTEM MEMORY & INPUT / OUTPUT 2-1
MAPPING
2.1 MEMORY MAPPING……………………………… 2-1
2.2 INPUT / OUTPUT MAPPING……………………… 2-2
2.3 POWER SUPPLY …………………………………… 2-3
i

3. PAGE NO. PAGE NO.
CHAPTER 3 CHAPTER 5
OPERATING INSTRUCTION-KEYBOARD…………. 3-1 MACHINE LANGUAGE PROGRAMMING…………. 5-1
3.1 KEYBOARD OPERATION…………………………………. 3-1 5.1 MONITOR SUBROUTINES………………………………… 5-1
3.2 SET , INR , DCR KEYS…………………………………….. 3-2 1. MODIAD…………………………………………… 5-3
3.3 REG………………………………………………………….. 3-3 2. MODIDT…………………………………………… 5-4
3.4 GO / EXEC………………………………………………….. 3-6 3. RDKBD …………………………………………….. 5-4
4. DELAY…………………………………………….. 5-4
3.5 STEP………………………………………………………… 3-7
5. CLEAR ……………………………………………. 5-5
3.6 VI : VECTOR INTERRUPT……………………………….. 3-10 6. GTHEX……………………………………………….5-5
3.7 RES : RESET………………………………………………. 3-10 7. OUTPUT…………………………………………….. 5-5
3.8 CODE………………………………………………………. 3-10 5.2 SERIAL ROUTINES…………………………………………..5-7
3.9 USER KEYS U1 , U2 , U3 , U4……………………………. 3-11 1. CIN………………………………………………….. 5-8
3.10 SAVE……………………………………………………….. 3-12 2. COUT………………………………………………. 5-8
3.11 LOAD………………………………………………………. 3-12 3. CROUT……………………………………………… 5-8
4. NMOUT…………………………………………….. 5-8
CHAPTER 4 5. GETHX …………………………………………….. 5-8
CODES………………………………………………….. 4-1 5.3 PROGRAMMING EXAMPLES…………………………….. 5-9
4.1 CODE 00 : MOVE BLOCK…………………………………. 4-1 EXAMPLE 1 : FAMILIARIZATION……………………….. 5-9
4.2 CODE 01 : FILL BLOCK…………………………………… 4-3 EXAMPLE 2 : RDKBD……………………………………… 5-11
4.3 CODE 02 : INSERT BLOCK………………………………. 4-3 EXAMPLE 3 : MODIDT……………………………………... 5-12
EXAMPLE 4 : RDKBD + MODIDT………………………… 5-12
4.4 CODE 03 : DELETE BLOCK………………………………. 4-3
EXAMPLE 5 : HEX ADDITION…………………………….. 5-12
4.5 CODE 04 : SEARCH BLOCK……………………………… 4-5 EXAMPLE 6 : 4 DIGIT HEX COUNTER…………………… 5-13
4.6 CODE 04 : HEX TO DECIMAL……………………………. 4-6 EXAMPLE 7 : 2 DIGIT DECIMAL COUNTER…………….. 5-14
4.7 CODE 06 : DECIMAL TO HEX……………………………. 4-7 EXAMPLE 8 : FLASHING DISPLAY………………………. 5-15
4.8 CODE 0E : COMPLEMENT BLOCK………………………. 4-7 EXAMPLE 9 : ROLLING DISPLAY………………………… 5-16
4.9 CODE OF : ROLLING DISPLAY…………………………… 4-8 TABLE 5.1 SCRATCH PAD LOCATION……………….. 5-2
ii TABLE 5.2 CHARACTER CODES………………………. 5-6
iii

4. PAGE NO.
CHAPTER 6 PAGE NO.
APPENDIX
SERIAL I/O OPERATION 6-1
A CONNECTOR AND STRAPPING DETAILS A-1
6.1 USE OF MONITOR 6-2 CONNECTOR J1 : DYNA BUS INTERFACE A-1
6.2 COMMAND STRUCTURE 6-2 CONNECTOR J2 : 8155 CONNECTOR A-2
6.2.1 D – DISPLAY MEMORY COMMAND 6-3 CONNECTOR J3 : 8255 CONNECTOR A-3
6.2.2 G – PROGRAM EXECUTE COMMAND 6-3 CONNECTOR J4 : 8279 CONNECTOR A-4
6.2.3 I – INSERT INSTRUCTIONS INTO RAM-1 6-3 CONNECTOR J5 : POWER SUPPLY CONNECTOR A-4
6.2.4 M – MOVE MEMORY COMMAND 6-4 CONNECTOR J6 : SERIAL CONNECTOR A-4
6.2.5 S – SUBSTITUTE MEMORY 6-4 CONNECTOR J7 : 8253 CONNECTOR A-4
6.2.6 X – EXAMINE / MODIFY CPU 6-5 STRAPPING DETAILS A-5
REGISTER COMMAND
6.3 PROGRAM DEBUGGING 6-7 B ADD-ON CARDS FOR MICROFRIEND B-1
DYNA-85 SYSTEM
6.4 ERROR CONDITIONS 6-8
6.5 ADDRESS VALUE ERRORS 6-8 C CIRCUIT DIAGRAM C-1
6.6 COMMAND EXAMPLES 6-9 D MICROFRIEND DYNA-85 MONITOR LISTING D-1
6.7 AUDIO CASSETTE INTERFACE 6-9
TABLE 6.1 BAUD RATE SELECTION 6-11 E PROCEDURE FOR UPLOADING AND E-1
DOWNLOADING
CHAPTER 7
FOR THE MICROFRIEND ILC USER 7-1
iv
v

5. INTRODUCTION
INTRODUCTION TO MICROFRIEND DYNA-85
What will I get DYNA-85 !
Microfriend DYNA-85 is an introduction to a low cost trainer and
development kit. It was developed to assist the novice to get familiar
with INTEL 8085 microprocessor in a user friendly environments.
This user’s manual tells you about –
Hardware of DYNA-85.
Monitor commands to interact with DYNA-85.
Memory & I/O details of Dyna-85.
Working with hex keypad and display.
Serial I/O and Audio cassette interface.
Circuit diagram and connector details.
Before you begin :
1) Study this manual carefully.
2) Write your own programs after studying the chapter on
Machine Language programming and try them out.
3) Do not hesitate to experiment using the I/O lines for real
world interfacing.
1

6. 1-1
CHAPTER 1
CONFIGURATION OF MICROFRIEND DYNA-85
1.1 SYSTEM OVERVIEW
MICROFRIEND DYNA-85 is a single board computer based on 8085A
CPU designed specially for training and development applications.
It is equally useful for a novice as well as development engineers for
studying the 8085A CPU and developing various product based on the
8085A.
1.1.1 SYSTEM HARDWARE OVERVIEW
CENTRAL PROCESSING UNIT
MICROFRIEND DYNA - 85 I s based on the INTEL 8085A high
performance CPU operating at 3 MHz.
MEMORY
Powerful system monitor has been provided on a 2732 EPROM
covering 4K bytes.This monitor includes all standard commands,
codes , functions and utility subroutines.
A 6116 battery back up RAM ( 2K ) is provided on the board for
inputting and executing programs.
Three 28 pin sockets are provided for memory chips so that further
expansion of RAM/EPROM is possible upto a maximum of 56K .

7. 1-2 1-3
HEX KEYPAD / DISPLAY INTERFACE a
A Keypad with 21 keys and 6 digits LED seven segments display is
provided for interaction with the system using 8279 keyboard /
display controller. This chip provides the following features. f b
g
Simultanous Keyboard & Display operation.
Scanned Keyboard Model sensor Mode.
2 Key locked / N Key roll over.
Contact Debounce. e c
16 Displays
Programmable scan timing.
d
The hex keypad has the standard hexadecimal keys and many other
function and Code keys. 4 “User Definable” function keys are also Writing a 1 in the desired bit lights that particular segment.
provided which can be defined by the user . All scan, return, shift and PARALLEL I/O INTERFACE
control lines of 8279 are brought on to connected J4. 46 parallel I/O lines are provided on board , 22 from 8155 and 24 from
8255 . These lines are brought on to connector J2 ( for 8155 ) and
(for 8255).
8279 DATA FORMAT :
SERIAL I/O AUDIO CASSETTE INTERFACE
The data format for the character being displayed by the 8279 is one bit Serial I/O is available through RS232C compatible port. The SID & SOD
corresponding to each segment of the seven segment display plus one lines are used under software control for serial operation . Baud rate is
bit for the decimal point. The display bits are store in the 8279 in the adjustable.
form of one byte digit of the display from RAM location 0 to 5 .
Onboard Audio Cassette I / F is provided with file management , for
The byte format is as follows : storage and retrieval of data using a cassette recorder.
A3 A2 A1 A0 B3 B2 B1 B0 TIMER
c d b a e g f dp Three channels of 8253 chip , a 16 bit TIMER / COUNTER and one
channel of 14 bit TIMER /COUNTER of 8155 are provided on board. All
lines of 8253 are provided on connector J7 and 8155 are provided on J2.

8. 1-4 1-5
EXPANSION SLOT STEP : Allows the user to execute the program on single step
All Address, Data, Control and Hardware Interrupt lines are brought on mode or break point mode.
to a 50 pin FRC connector for system interfacing and expansion. These SAVE : Used for saving the contents of memory onto an audio
lines are unbuffered so user has to take care while expanding their cassette.
system. LOAD : Used for loading the program from audio cassette back
1.1.2 SYSTEM COMMANDS OVERVIEW to the memory in RAM area.
The HEX KEYPAD mode supports the following commands : U1..U4 : These keys are user definable functin keys. The function
of these keys can be defined by the user , by loading the
RESET : Provides hardware reset . Display shows “FrlEND” on
appropriate memory locations with vectors pointing to
pressing this key.
user subroutines.
VI : Vector interrupt key.Activate RST 7.5 vectored interrupt.
1.1.3 SYSTEM FIRMWARE OVERVIEW
SET : Allows the user to examine & modify the contents of
RAM and only examination of contents is possible in
case of EPROM.
The MICROFRIEND DYNA-85 has very powerful and user
friendly FIRMWARE in the EPROM.
INR : Increments memory address presently displayed un the
address field of display. Complete listing of the Monitor FIRMWARE is given at the end of
User can borrow any subroutine from the listing for his own
DCR : Decrements memory address presently displayed in the program development.
address field od display. Various commands available through the keyboard and the coded
REG : Allows the user to examine contents of CPU registers & subroutines are accessible through the CODE key and is already been
modify them if necessary. listed in chapter.
GO : Allows the user to load the program counter by the A point worth mentioning here about the FIRMWARE is the options of
desired memory address which is the starting address of entry point to the Monitor.
the program to be executed.
There are two options available , one is the COLD START , other is
EXEC : Used to start the execution of GO or CODE command. WARM START . In COLD START entry the system is completely
CODE : Used for selecting one of the coded subroutines in the reinitialized and no user program status is saved from the previous
monitor. program executed. This is equivalent to the hardware reset.

9. 1-6 1-7
COLD START entry can be performed through software by using the The areas of application on MICROFRIEND DYNA-85 are as follows :-
RST 0 instruction.
1. Analog to Digital Converter Interface.
In WARM START entry, the start of previously executed user program is
2. Digital to Analog Converter interface.
fully saved before entering the monitor. WARM START entry is possible
3. Interfacing Hexadecimal Keyboad.
through software by using th RST 1 instruction.
4. Simulation of an Elevator.
In both cases, the sign on display is ‘FrlEND’ as in case of hardware 5. Temparature Controller Interface.
reset through RESET Key. 6. Stepper motor Controller.
CODE COMMANDS : 7. Traffic Light Control System.
8. DC Motor Controller.
CODE 00 : Move a block of memory.
9. Thumbwheel Interface.
CODE 01 : Fill a block with a data byte.
CODE 02 : Insert a byte in a block. And many more experiment and application can be thought and
CODE 03 : Delete a byte from a block. successfully developed on MICROFRIEND DYNA-85 system.
CODE 04 : Search a given block for a given pattern.
CODE 05 : Hex to Decimal conversion.
CODE 06 : Decimal to Hex conversion.
CODE 0E : Complement a block.
CODE 0F : Rolling Display.
1.1.3 APPLICATION OF MICROFRIEND DYNA-85
MICROFRIEND DYNA-85 is the low cost learning and development
system for beginners as well as development engineers
The powerful friendly FIRMWARE allows you to learn all application of
8085A and its support chips like 8255 PPI. 8155 PPI and Timer . 8279
prgrammable keyboard and display controller,8253 Programmable timer
and counter etc.You can load,debug and finialize your program on the
MICROFRIEND DYNA-85 and nce the development is finilize it can
also be used as an OEM board.

10. 2-1
CHAPTER 2
SYSTEM MEMORY & INPUT / OUTPUT
MAPPING
2.1 MEMORY MAPPING
The system memory is also as important as the CPU itself , because this
is where the system program resides and the CPU takes its instruction
from the program. The memory is of two types ROM and RAM i.e.
READ ONLY MEMORY & RANDOM ACCESS MEMORY.
The MICROFRIEND DYNA-85 has a flexible memory map , and for
your convenience for program development, the RAM has useful feature
such as battery back-up.
FFFF
USER
RAM
IC 6116
C000
BFFF
EXPANSION
EPROM/RAM
4000
3FFF
MONITOR
0000 EPROM

11. 2-2 2-3
0000H TO 3FFFH :
IC ADDRESS MODE I/O FUNCTION
Monitor EPROM socket.Monitor 2732 is located at 000H to 0FFFH and
is mapped at 1000H-1FFFH,2000H-2FFFH and 3000-3FFFh also. 8255 10 R/W PORT A
11 R/W PORT B
It 2764 / 27128 are used , 1000H - 3FFFH can be used for further 12 R/W PORT C
expansion. 13 WRITE CONTROL REGISTER
4000H to BFFFH : 8253 18 R/W COUNTER 0
19 R/W COUNTER 1
This Socket is used for user expansion of EPROM and RAM. 1A R/W COUNTER 2
EPROMs like 2716 / 2732 / 2732 / 2764 / 27128 / 27256 or RAMs 1B WRITE CNTROL REGISTER
like 6116 / 6264 / 62256 can be installed by suitable strappings.
C000H to FFFFH :
User RAM socket.The 2K user RAM IC 6116 is located at F800H- 2.3 POWER SUPPLY
FFFFH.This 2K memory is folded after every 2K bytes from C000H to
FFFFH.In this socket 6264 can also be used.
2.2 INPUT/ OUTPUT MAPPING
Recommanded Power Supply for DYNA-85 kit
DMS SMPS – 01
IC ADDRESS MODE I/O FUNCTION
Having following specification :
8279 04 READ READ KEYBOARD FIFO
WRITE WRITE DATA TO DISPLAY
05 READ READ STATUS WORD Voltage Current Rating
WRITE WRITE COMMAND WORD
+5V 1A
8155 08 WRITE COMMAND/STATUS + 12 V 500 mA
REGISTER
09 R/W PORT A
- 12 V 250 mA
0A R/W PORT B + 30 V 100 mA
0B R/W PORT C
0C R/W TIMER LOW BYTE
0D R/W TIMER HIGH BYTE

12. 2-4 3-1
CHAPTER 3
OPERATING INSTRUCTION- KEYBOARD
KEYPAD LAYOUT :
3.1 KEYBOARD OPERATION
RESET VI C D E F MICROFRIEND DYNA-85 has a built in keyboard ( KEYPAD).The layout
U1 U2 U3 U4 of the keypad is given on the opposite page for ready reference. The
system can also be operated through a console connected to the serial
interface.
While using the built in keyboard , we can work only in the Hexadecimal
DCR 8 9 A B number system . There are 16 keys for entering Hex numbers from 0
GO/H LOAD SAVE to F. These are all dual meaning keys and the key designated depends
L
on when the key I s pressed. In addition to these 16 keys there is one
vector Interrupt key, one RESET key and 3 function keys.
When the system is switched on the display shows , sign – on message
EXEC 4 5 6 7 ’F r l E n d’. This indicates that the system is reset and the monitor
SPH SPL PCH PCL expects a command from you. At this moment any one of the command
keys : SET , CODE , STEP, REG, GO, LOAD or SAVE can be pressed
depending on the desired operation.
In case any non command key is pressed, the display will show ‘FErr’
message, you can again press a valid command key or press RESET
INR 0 1 2 3 and then press a valid command key.
SET CODE STEP REG/I
The various command and function keys are explained below :

13. 3-2 3-3
3.2 SET,INR,DCR KEYS EXAMPLE 1 :
Key Pressed Address Field Data Field
You can use the SET key to set the address of the memory location to
be accessed. On pressing SET key the display becomes blank and a dot RES F r I E n d
appears in the Address field which is made up of the first four digit of the
six digit display . The remaining two digit of the six digit display are the SET
data field .The dot in the address field indicates that your next key will be F 0 0 0 F
treated as an address entry (entry is from Right to Left and last 4 entries 0 0 0 F 0
are retained). 0 0 F 0 0
0 F 0 0 0
When you have entered the 4 digit hexadecimal address press the INR
key which will terminate the address entry and display the c ontents of INR F 0 0 0 X X
that memory location as the two digits in the data field. 3 F 0 0 0 0 3
E F 0 0 0 3 E
Now you can modify or retain the contents of the location. INR F 0 0 1 X X
DCR F 0 0 0 3 E
Pressing INR key again will load the data field into the memory location
at the address shown in the address field . This key also increments the EXEC F
address by 1 location and dispalys the contents of that new locaton with
required data.
Pressing EXEC key terminate the loading of memory and the monitor
DCR key also works in a similar way but it decrements the address by 1
waits for next command.
and points to the previous location.
Trying to load data into a Monitor EPROM location using SET key 3.3 REG
results in ‘FErr’(error).
This key allows you to examine and optionally modify the contents of
SET, INR, DCR, keys can also be used to verify the data loaded in RAM
all 8085 internal registers.
by displaying one location after another.
Pressing REG key will blank the display and a dot appears in the
Field.
Next press a valid register name. The Register names appears on
various
hexadecimal number keys as follows :-
3 : I ( Interrupt Mask )
4 : SPH ( Stack Pointer High )
5 : SPL ( Stack Pointer Low )

14. 3-4 3-5
6 : PCH ( Program Counter High Format of the F register ( Flag Register ) is as follows :
7 : PCL ( Program Counter Low )
8 : H ( H Register )
9 : L ( L Register )
S Z X AC X P X C
A : A ( A Register )
B : B ( B Register ) X : Don’t care.
C : C ( C Register ) C : Carry
D : D ( D Register ) P : Parity
E : E ( E Register ) X : Don’t Care
F : F ( Flag register ) AC : Auxillary Carry
Z : Zero
Pressing any one of these keys after pressing REG key will display the S : Sign
particular register name in the address field and the contents of that
register will be displayed in the data field. EXAMPLE 2 :
Pressing INR key after this , will point to the next register and DCR will
point to the previous register. Key Pressed Address Field Data Field
Contents of the register can be modified at this point similar to loading
any other memory location.
REG .
Pressing INR and DCR keys after modifying the contents of that register
A A X X
and ENTER terminates the command. Address field shows F in the left
0 A 0 0
most digit , the monitor indicates as usual that the it is waiting for the
5 A 0 5
next command.
0 0 5 0
Format for the I register (Interrupt mask) is as follows : INR B X X
I M M M DCR A 5 0
EXEC F
0 0 0 A E 7.5 6.5 5.5
I Interrupt enable Flag [ 1 is enabled, 0 is disabled ]
M Interrupt Mask [1 is masked , 0 is unmasked ] NOTE : ONLY LAST TWO ENTRIES ARE RETAINED.

15. 3-6 3-7
3.4 GO/EXEC 3.5 STEP
This pairs of keys is used to execute a program from a desired location We have seen how a program can be executed by using GO and
onwards. If the GO key is pressed, It displays the present address in the EXEC pair of keys.This method is useful only when the program is
program counter and the contents of the memory location at address. A finalized, or when we have a ready program.
dot appears in the address field indicating that you can enter a new In case a program is being developed , it is essential that we have
address in the address field. You can now modify the contents of the a ready program and it I s essential that we have a facility to check
the execution of program stage by stage and see the results.
program counter . After loading the desired starting address in the
address field , press EXEC key to execute the program starting at the This can be achieved in two ways . One way is to insert the RST 1
address .During execution of the program , the address field shows ‘E’ instruction ( CFH ) at every point where a break is desired to check
indicating that the user program or subroutine is being executed. status or result , which is possible only in case of short programs being
run from the RAM.
The Monitor Regains control either after pressing the RESET key
Another way is to use the STEP key and step through the program.
( Hardware Reset ) or after executing RST 0, RST 1, JMP 0000H or JMP
Pressing the STEP key displays the contents of the program
0008H instruction (Software Reset).
counter , Which can be modified to set the starting address of the
EXAMPLE 3 : program.
Now press INR and the monitor will prompt for other parameters :
Key Pressed Address Field Data Field
br : Break Address
GO P P P P X X Cn : N +1 , where N is the number of times the break should
F 0 0 0 F occur.
0 0 0 F 0
0 0 F 0 0 In case ‘br’ and ‘Cn’ both are given a value of zero,the system goes into
0 F 0 0 0 single stepping mode. In single stepping mode, the program os executed
EXEC F single instruction at a time . Execution stops after every instruction and a
status check is possible.
EXAMPLE 4 :
NOTE : P P P P IS THE PRESENT CONTENTS OF PROGRAM Let us take a simple program to see how the STEP command
COUNTER WHEN GO KEY WAS PRESSED. XX IS THE DATA IN works.Load
MEMORY LOCATION P P P P.
the following program starting at location F000H.

16. 3-8 3-9
Address Data Mnemonic
Key Address Data Comments
F000 3E 05 MVI A, 05h Pressed Field Field
F002 3D DCR A
F003 C202F0 JNZ F002h STEP PPPP XX PRESENT PC
F006 76 HALT CONTENTS
This program first loads register A ( Accumulator ) with 05 , then F000 F000 STARTING ADDRESS
decrements the accumulator contents by 1 till the contents become zero INR . br BREAK POINT ?
0 0000 br IGNORE br.
and halts at that point.
INR Cn . Cn ?
The JNZ loop will make use of ‘br’ and ‘Cn’. First let us execute the 0 0000 00 IGNORE Cn.
program with STEP key and using ‘br’ and ‘Cn’ parameters. INR F002 3D FIRST INSTRUCTION
EXECUTED PC POINTS
Key Address Data Comments TO NEXT INSTR .
Pressed Field Field EXEC F PROGRAM STOPS FOR
REG . STATUS CHECK .
STEP PPPP XX PRESENT PC CONTENTS A A 05 REG . A (Acc)
F000 F000 STARTING ADDRESS CONTENS 05
INR . br BREAK ADDRESS ? EXEC F NEXT COMMAND ?
F002 F002 br BREAK AT F002 STEP F002 3D STEP
INR Cn . Cn ? INR F003 C2 SECOND INSTR.
04 Cn 04 Cn 4 N + 1 EXECUTED
INR F002 3D PROGRAM STOPS AFTER EXEC F PROGRAM STOP FOR
BREAKPOINT OCCURRED 3 STATUS CHECK
EXEC F TIMES REG . REGISTER A (Acc)
REG . EXAMINE REG.A CONTENTS 04
A A 02 A A 04 AFTER
DECREMENTING
As the program stopped after the breakpoint occurs 3 times, the original ONCE
contents of register A which were 05 have been decremented three
times. The register A should now contain 02, which is displayed in the After counting this sequence till the contents of A become 00, the
data field. program comes out from the JNZ loop and the address field shows the
The same program can be executed in a single stepping mode. last address of the program , i.e. F006H. Contents of this location
are displayed in the data field as 76 (HALT). If you press EXEC at this
stage and examine the stage and examine the contents of register
A using REG command , the result will be 00 as expected.

17. 3-10 3-11
3.6 VI : VECTOR INTERRUPT 3.9 USER KEYS U1,U2,U3,U4
This key is used to interrupt the program execution and transfe r the There are 4 user definable keys on the MICROFRIEND DYNA-85. Each
control to location 003CH in the monitor.This location has a jump to of these keys has a vector in the scratchpad RAM area . By loading
location FFCEH in the user RAM.By inserting another jump instruction at an appropriate jump instruction at these location, you can define the
functon of keys U1, U2, U3, U4.
FFCEH , we can transfer the control to an interrupt service routine
located to another area in the memory. The vector location are as follows :
For proper operation of this key, the user program must enable the
interrupt through the EI instruction and the RST 7.5 must be unmasked
Key Memory Location
using the SIM instruction.
The exmple of a decimal counter included in the chapter on U1 FF9CH, FF9DH, FF9EH
programming, will make the application of key will make it more clear. U2 FF9FH, FFA0H, FFA1H
U3 FFA2H, FFA3H, FFA4H
3.7 RES : RESET U4 FFA5H, FFA6H, FFA7H
Pressing RES key causes a hardware RESET operation.The control is An example will illustrate how these keys can be used . There is a
transferred to location 0000H in the monitor. The monitor program is subroutine in the monitor for a “ROLLING DISPLAY” at location 0E5BH.
executed from 0000H onwards without saving the status resulting from Using the SET key load a jump instruction C3 5B 0E at location FF9CH,
any user program executed before the ‘RESET’. The display shows FF9DH and FF9EH which are the U1 key vector location.Mow reset the
‘F r l E N D’ as the sign-on message and the monitor waits for a valid system and then press U1 key, the display immediately blanks for a
command. moment and then a rolling message appears
3.8 CODE
D Y n A L o G h E L P S Y o U L E A r n I n G U P
The code key allows you to access one of the coded subroutines in the By using the U1 key vector, ypu have efficiently transferred the control to
monitor firmware. All the user accessible coded subroutines are the rolling display subroutine.
explained in Chapter 4.

18. 3-12 3-13
3.10 SAVE 2. Press LOAD key, enter the File Number Fn of the program to be
loaded.( A hex number between 00 & FF )
3. Turn CTR ON, keep it in PLAY mode.
This command is used for saving your program on an audio cassette.
The procedure for saving is as follows : 4. Immediately press EXED Key. L appears in the data field, indicating
that the CPU is searching for the file with file number Fn.
1. Command the MIC socket (on the top) of the MICROFRIEND
DYNA – 85 to the MIC socket of the CTR. 5. Whenever the CPU comes across any File Number , it is displayed
in the data field. Loading starts only when the specified File
2. Press SAVE key, enter the following parameters number is found and displayed.
SS : Source Start 6. The SS parameter of your program is already saved on the cassette
SE : Source End tape, and when the program is being loaded back into RAM , it
Fn : File Number – any hex number from 00 to FF. automatically gets loaded at the same address.
3. Turn CTR ON and keep it in RECORD mode. 7. On completion of loading the program with File number Fn , SS
parameter is displayed in the address field.
4. Press the EXEC key, S appears in the data field indicates that your
program is being saved on the audio cassette.
5. On completion of SAVE operation, F r l E n d appears again on the NOTE : There shouldn’t be a gap of more than 10 sec. Between
display. turning CTR ON and pressing EXEC key.
6. Turn CTR OFF.
3.11 LOAD
This command loads your program from the cassette to the RAM . The
procedure for loading is described below :
1. Connect the EAR Socket of MICROFRIEND DYNA-85 to the EAR or
external speaker socket of the CTR. (Select volume control setting
by trial)

19. 4-1
CHAPTER 4
CODES
As we have seen in the previous chapter, the code key allows us to access
the various coded subroutines from the monitor program. It is not essential
to remember the starting location addresses of all these subroutines, as
they have been coded to be used with the CODE key.
A “Code Referance Chart” has been included in this chapter for quick
referance. Detailed explainaton of operation of all the coded are given
below.For executing any code,the ‘CODE’ key is pressed. A dot appesrs in
the data field,indicating that the code number should be entered and will be
displayed in the data field. Now enter the code number and press INR key.
The data field prompts for the data field or the address field will prompt for
the next parameter to be entered.
After entering all the parameters,the code can be executed using the INR or
EXEC key.
4.1 CODE 00
Move a Block of Memory
This code moves a block of memory from one place to other . The
parameters required to be entered are SS : Source Block starting address,
SE : Source Block end address and dS : Destination Block start address.
A point to remember here is that dS must always be a RAM address.Trying
to move a block to monitor EPROM results in an error. Please see Chapter 5
for further explanation of this point.

20. 4-2 4-3
Example : 1
4.2 CODE 01
Key Pressed Address Field Data Field
Fill Block with a Data Byte
CODE
This code requires the following parameters :
0 0 0.
INR . SS SS : Starting address of the block.
0 0 0 0 0. SS SE : End address of the block.
INR . SE Sr. : Data byte to be filled in all the location from SS to SE
5 0 0 0 5. SE Sr. can be any hex number from 00 to FF must be within the RAM area.
INR . dS
F000 F 0 0 0. dS 4.3 CODE 02
EXEC FrIE nd
Insert Byte in a Block ( SE, Sr,IA )
This example program moves a block of memory between 0000H and In a given block of RAM it is sometimes necessary to insert a byte of data
0005H to the RAM address F000H. which is missing. A given byte in Sr is inserted at a given insert address IA.
The remaining block shifts down by one position, upto the address given by
This can be verified by using the SET key as follows : SE.
No address relocation for jumps are done.
Key Pressed Address Field Data Field
4.4 CODE 03
SET F 0 0 0.
INR F000 3E Delete a Byte at a Given Address ( SE,DA )
INR F001 0 0. In a given block at a given address DA, a byte is deleted. The remaining
INR F002 d 3. block till SE shifts up by one position. The above two INSERT and
INR F003 0 5. DELETE commands are very useful in inserting or deleting a display
INR F004 00 character in the VIDEO RAM at the given cursor position.
INR F005 C3

21. 4-4 4-5
Ex : INSERT BYTE You can insert anything else.
With the SET command verify that 3E,00,D3,05,32,FF,20,19,76 is
Load the RAM location 1000H-1007H with the help of SET command. the data from location 1000H-1008H. The block has shifted down by 1
byte.
1000 3E After loading we notice that the instruction to
1 00 store accumulator STA 200FFH is incorrect.The
The opposite of INSERT is DELETE and it works as follows :
2 D3 ‘OPCODE’ 32 is missing. It has to be inserted
3 05 before FF , 20 Key Pressed Address Field Data Field
4 FF
5 20 CODE
6 19 03 0 3.
7 76 EXEC . SE
8 XX 1008 1 0 0 8. SE
If the block is small you an manually make 1004 as 32 and reload INR . DA
theremaining by shifting one down. But if the block is very tedious. To 1004 1 0 0 4. DA
Do this use INSERT byte command.IA (Insert Address ) is 1004. SE EXEC FriE N D.
( Block End ) is 1007 and Sr ( Insert byte ) is 32.
With the SET command verify that 1000-1007 contents are same as
Key Pressed Address Field Data Field before the INSERT command (i.e 1004 ; FF etc.)
CODE 4.5 CODE 04
02 02
EXEC SE
1007 1 0 0 7. SE Search a Given Block for Given Pattern ( SS,SE,Sr )
INR IA
The given block of memory (RAM or ROM ) between SS and SE is
1004 1 0 0 4. IA
searched for a pattern o f byte given in Sr. Whenever the first match
INR Sr
is found, the address and bytes are displayed. Remaining mismatches
32 Sr 32
can be scanned with INR.
EXEC FriE N D.
LOAD the data in Ex.4.3 from 1000H.

22. 4-6 4-7
Ex : BLOCK SEARCH 4.7 CODE : 06
Key Pressed Address Field Data Field Decimal to Hex Conversion
This code is useful for converting any Decimal number from 0000 to
CODE
9999 into a Hex number equivalent.
04 0 4.
EXEC . SS The parameter to be entered is dE, which is the decimal number we
1000 1 0 0 0. SS desire to convert into Hex format.
INR SE
Pressing EXEC after entering the decimal number displays the Hex
1008 1 0 0 8. SE
equivalent. An important precaution to be taken is that , when you are
INR Sr .
entering the decimal number to be converted to Hex, do not press any
19 Sr 1 9.
keys from A to F. There is no provision for detecting this error and the
EXEC 1006 19
results of converting that number are unpredictable.
INR FriE nd
CODE 05 and CODE 06 are very useful in address conversions,relative
jumps and total space calculations.
4.6 CODE : 05 4.8 CODE : 0E
Hex to Decimal Conversion Complement a block of memory
This code complements all the data contained within a memory block :
CODE 05 is a utility code for converting any Hex number from 0000 to The required parameters are :
FFFF into a Decimal number.
SS : Starting address of the block.
The parameter to be entered is prompted in the data field as HE, and the SE : End address of the block.
Hex number to be converted can now the directly entered in the Address
field. Pressing EXEC displays the Decimal equivalent of the Hex number On executing this code, all the ‘0’ are replaced by ‘1’ by ‘0’ within the
entered. specified block of memory.
SS and SE must be in RAM area.

23. 4-8 5-1
CHAPTER 5
4.9 CODE : 0F
MACHINE LANGUAGE PROGRAMMING
Rolling Display
5.1 MONITOR SUBROUTINES
This is not a utility code but it is a demonstration code to illustration code
illustrate the powerof the display control.
This section will cover the applications from the software point of view of
MICROFRIEND DYNA - 85 . You are advised to get familiar with the
On executing 0F, the display starts rolling the message :
assembly language of INTEL 8085 Microprocessor.You should get familiar
d Y n A L o G h E L P S Y o U in L E A r n I n G UP. with the various mnemonics and their power.
CODES REFERANCE CHART The 8085 microprocessor makes use of a 16 bit internal register called the
stack register to point to a memory area called stack. The stack uses the
Code Function Parameters LIFO ( Last In First Out ) type for storage during subroutine calls.
User is advised to initialize the Stack Pointer with his stack area.The
00 Block Move SS,SE,dS
suggested stack pointer location is FEFFH. Location beyond this should
01 Fill Block SS,SE,Sr
not be utilized by the user as the monitor uses this area as the scratch-pad
02 Insert Byte SE,IA,Sr
RAM.
03 Delete Byte SE,dA
04 Block Search SS,SE,Sr
You may borrow several monitor routines to simplify your task of
05 Hex to Dec HE
programming and to minimize RAM used. From the Firmware listing
06 Dec to Hex dE
provided, take care of noting the parameters required by these routines,
0E Complement Block SS,SE
as some of the routines destroy the contents of the Registers.
0F Rolling Display
Also go through the manuals for the detailed operation of 8155, 8255 and
SS : Statrting Address 8279 supporting chips.
SE : End Address
dS : Destination The following is a list of scratch-pad RAM allocation to the Monitor
IA : Insert Address program.
DA : Delete Address
Sr : Data Byte

24. 5-2 5-3
TABLE 5.1
Location (Hex) Used for Location (Hex) Used for
FF9 A, B HALF BIT FFED Flags
FF9 C, D, E U1 Key Jump FFEE A Register
FF9 F, 0, 1 U2 Key Jump FFEF L Register
FFA2, 3, 4 U3 Key Jump FFF0 H Register
FFA5, 6, 7 U4 Key Jump FFF1 Interrupt Mask
FFA8 P DATA FFF2 Prog. Cntr – Low Byte
FFAA, B Unused FFF3 Prog. Cntr – Hi Byte
FFAC, CnSave FFF4 Stack Ptr – Low Byte
FFAD, E BrSave FFF5 Stack Ptr – Hi Byte
FFA, F, 0 DESAVE FFF6 Current Address
FB1 CARRYLOC FFF8 Current Data
FFB2, 3 HESAVE FFF9-FFFC Output buffer & Temp Loc
FFB4, 5 DASAVE FFFD Register Pointer
FBB6, 7 IA SAVE FFFE Input Buffer
FFBB, C SE SAVE FFFF 8155 command/status Register Image
FFB9, A DS SAVE
FFBD, E SS SAVE
FFBF COPY TEST Important subroutines which can be borrowed from the Monitor
FFC0, 1 BIT TIME FIRMWARE are listed below.These subroutines can be called in your
FFB8 SR SAVE own programs by using the CALL Instruction and specifying the
FFC2 User may place a JMP instr. to a RST 5 starting address of that particular subroutine.The starting addreses of
routine in locs FFFC2H-FFFC4H
all these subroutines are given in brackets along with their names.
FFC5 JMP to RST 6 routine
FFC8 JMP to RST 6.5 routine 1. Modiad (0362) – Modify address field of display
(Hardwored user interrupt)
FFCB JMP to RST 7 routine Inputs
FFCE JMP to ‘VECT INTR’Key routine
FFDI-FFE8 Monitor Stack B : Dot Flag-
(temporary storage Used by Monitor 1 Put dot at right edge of the field.
FFE9 E Register 0 No dot.
FFEA D Register
FFEB C Register HL : The character to be displayed.

25. 5-4 5-5
The contents of HL Register pair are displayed in the address field.The 5. CLEAR (01D7)
contents of all the CPU registers are affected
Inputs : B : Dot falg –
2. MODIDT ( 036E ) 1 – Dot in address field
0 – No Dot
Inputs B : Dot Flag-
1 : Put Dot at the right edge of the field This routines sends blank characters to both the address field and data
0 : No dot field of the display. If the dot flag is set then a Dot appears at the right edge
The contents of the A register are displayed in hex notation in the data field of the address field.
of display the contents of all the CPU registers and flags are affected.
6. GTHEX (022B) – Get Hex Digits
3. RDKBD (02E7)
Inputs : B : Display Flag –
Input : Nothing 0 – Use address field of display.
1 – Use data field of display.
Output : A : character read from the keyboard Outputs : A : Last character read from keyboard.
DE : Hex Digits from keyboard last four entered.
Destroys : A, H, L, F/E’s. Carry : Set : At least one hex digit read, else it is reset.
Destroys contents of all registers.
This routine waits until a character is entered om the hex keypad and on
return, places the value of the character in the A register. This routine accepts a string of hex digits from keyboard and displays
them in address / data field as they are received. In either case a dot will be
displayed in the right most field. It is not terminated by INR, DCR or EXEC
For the RDKBD routine to work correctly, the user must unmask RST 5.5 keys, the received hex digits are invalid.
hardware interrupt using the SIM instuction in Version 1.
7. OUTPUT (02B7)
4. DELAY (05F1) Inputs : A : Display Flag –
0 – To use address field
This routine takes the 16 bit contents of register pair and counts down 1 – Use data field
to zero.Then returns to the calling program. The A,D & E register and flags
are affected.

26. 5-6 5-7
B : Dot Flag –
Character Hex Code
1 - Dot at right edge
0 - No dot H 10
L 11
HL : Address of characters to be output.
P 12
Destroys all I 13
r 14
Outputs two characters to data field or four to address field. The address of Blank 15
the characters is received as an argument. The routines MODIDT and n 16
MODIAD are useful whenever the user wants to display hexadecimal U 17
information like messages. The userhas to use the output routine with the h 18
following code assigned to the characters to be displayed. The display G 19
technique on 7 segment LED is already explained. J 1A
y 1B
TABLE 5.2 O 1C
Character Hex Code
5.2 SERIAL ROUTINES
0 00
1 01
The following are the routines you can borrow from the serial Monitor.
2 02
Whenever the user straps the SID to TTY ( 20 mA loop ) or CRT
3 03
(RS232C) the serial routine is invoked. The serial routine is AUTOBAUD
4 04 type i.e. on power up or RESET, the contents for HALFBIT and BITTIME
5 05 are undefined. After sending ASCII space character (20H) from a serial
6 06 device, and baud rate is calculated . A BRID routine and a sign on
7 07 message is transmitted at that baud rate. Thus user is advised to set the
appropriate values in HALFBIT and BITTIME and then use CIN and
8 08
COUT routines for any other purpose of block transfer on serial link from
9 09 one system to another etc. Please refer to the chapter on serial I/O
A 0A operation for details, before using any of the following routines which can
b 0B be obtained from the serial monitor.
C 0C
d 0D
E 0E
F 0F

27. 5-8 5-9
1.CIN (07FD) – Console Input The following are the program examples . The user should load and
execute these program to get familiar with the keyboard of
This routine returns a character in ASCII code received from the serial MICROFRIEND DYNA-85.
devices,to the A register. Condition flags are affected.
5.3 PROGRAMMING EXAMPLES
2.COUT (07FA) – Console Output
Example 1 : Familiarizaton
This routine transmit a character (in ASCII Code) passed from the program in
C Register to the serial device. The A, C & F registers are affected. Let us start with a simple program to understnd exactly what happens
inside a microprocessor when a program is run.
3.CROUT (05EB) – Carriage Return Line Feed
First, load the following program using ‘SET’ and ‘INR’ keys.
CROUT send CR and LF characters to console, A, B, C and F are destroyed.
Address Data Mnemonic Comments
4.NMOUT (06C6) – Hex Number printing
NMOUT converts the 8 bit unsigned integer in A register to 2 ASCII F000 31 FF FE LXI SP Define Stack Pointer
characters representing 2 hex digits and prints the two digits on console. F003 00 NOP
Contents of A,B, and C, F are destroyed. F004 00 NOP
F005 00 NOP
5.GETHX (0626) F006 00 NOP
F007 00 NOP
Outputs : BC : 16 Bit Integer F008 00 NOP
D : Character which terminated the integer. F009 CD 6E 03 CALL Display contents of A into
Carry : 1 – First character is not delimiter Data Field
0 – If first character is delimiter. F00C 76 HALT Stop Executing
Destroys : A, B, C, D, E & F.
Now to understand exactly how the program works, let us take three
GETHX accepts a string of hex digits from the input stream and returns a simple instructions.
value, a 10 bit binary integer, taking only last four digits entered.
MVI A, D8
MVI B, D8
ADD B
RST 1

28. 5-10 5-11
The RST 1 instruction will be used so that the register status is saved and Execute the program at F000H and examine registers A & B, this
we can examine registers after executing the programs , using the ‘REG’ time the contents of register A are not 23 as before, but it is 34.
key. This is the result of instruction
a. Execute the program that has been entered at location F000H by ADD B, 80
using the ‘GO’ and ‘EXEC’ keys .‘E’ will appear in the address field Which contents of B are added to A, A become 34 (23+11).
showing that the program is being executed. Press ‘RES’ to reset
e. Now remove the CF from location F008 and replace it by 00 (NOP)
and ‘FrlEnd’ will appear.
again. Execute the program at F000H and observe the difference.
b. Modify the initial contents of location , as follows : This time the data field shows 34.Instruction CALL MODIDT has
F003 3E displayed the contents of register A in the data field.Execution of
F004 23 program now select different sets of instruction and study the effect
F005 CF of executing those instruction in the similar manner.
Execute the program at F000H and examine the register A and B. In case of long programs, it is very inconvient to insert the CF and
remove it for each step. Such programs can be studied by using
Contents of A should be 23, because the instruction MVI A , 23 the ‘STEP’ key which is already explained.
(3E 23 ) will load register A with 23.
Example 2 : RDKBD
c. Modify the locations again as follows :
The following program illustrate the utility of the subroutine RDKBD.
F005 06 Execute the following program and then examine register A . Register A
F006 11 will contain the value of the key you has pressed.
F007 CF
Address Data Mnemonic Comments
Execute the program at F000H and examine the registers A and B. F000 32 FF FE LXI SP, FEFF Define Stack Pointer
F003 00 NOP
Register A contain 23, and Register B will contain 11, because the F004 00 NOP
instruction MVI B, 11 (06 11) has now loaded the register B with F005 00 NOP
11.
F006 CD E7 02 CALL RDKBD Read Keyboard value
d. Modify the location again as follows : Into A.
F007 80 F009 CF RST 1 Save registers & return
F008 CF to monitor

29. 5-12 5-13
Address Data Mnemonics Comments
Example 3 : MODIDT
F000 31 FFFE LXI SP,FEFF Define stack pointer
This examples loads register A with a value and displays that value in the
F003 00 NOP
data field of the display.
F004 00 NOP
Address Data Mnemonic Comments F005 00 NOP
F006 CD E702 CALL RDKBD Read Keyboard into A
F000 31 FF FE LXI SP, FEFF Define stack F009 47 MOV B, A Transfer A to B
Pointer F00A CD E702 CALL RDKBD Read next key
F003 3E 96 MVI A, 96 Load A with F00D 80 ADD B Add B to A
Value 96 F00E CD 6E03 CALL MODIDT Display result in data
F005 CD 6E 03 CALL MODIDT Display contents field
F008 76 HLT of A in the data F001 C3 06F0 JMP F006 Wait for Next cycle
field
Addition Suggestions :
Example 4 : RDKBD + MODIDT 1. Modify this program using the DAA instruction to perform decimal
This example combines previous two programs and the Data field of display addition.
the value of the key pressed. 2. Write a program for 2 digit decimal addition using DAA and RLC
instructions.
Address Data Mnemonics Comments
Example 6 : 4 DIGIT HEX COUNTER
F000 31 FFFE LXI, SP FEFF Define stack
pointer This example program displays a 4 digit Hex count in the address field of
F003 00 NOP Unmak interrupt the display, from 000 to FFFF and again resets to 0000 before continuing
F004 00 NOP further count. The HL register pair is used for counting and the MODIDT
F005 00 NOP subroutine is used to obtain the display.
F006 CD E702 CALL RKBD Read keyboard
Into A Address Data Mnemonic Comments
F009 CD 6E03 CALL MODIDT Display A into
data field F000 31 FFFE LXI SP,FEFF Define stack pointer
F00C C3 06F0 JMP F006 Wait for next key F003 21 0000 LXI H, PUSH H Save HL on stack
F007 CD 6203 CALL MODIAD Display count in
Example 5 : HEX ADDITION address field
This program combines the RDKBD and MODIDT subroutines with the ADD F00A 11 0040 LXI D 4000 Set Delay
B instruction.The RDLBD subroutine reads two successive key entries and F00D CD F105 CALL DELAY Wait out Delay
adds them together in register A. The MODIDT subroutines then displays F010 EI POP H Restore HL
the result of this addition in the data field of the display. F011 23 INX H Increment count
F012 C3 06F0 JMP F006 Continue in loop

30. 5-14 5-15
Example 7 : 2 DIGIT DECIMAL COUNTER This program executedas GO F000 EXEC, and it can be stopped by
This program displays s decimal counter in the data field of display. The pressing the VI key.
count can be stopped using the VI key and restarted by pressing any key,
except the Reset key. The address field shows ‘E’ to indicate that user The count can be restarted by pressing any key other than Reset key.
program is being executed.
Address Data Mnemonics Comments 1. Change the speed of counter by modifying the contents of location
F011H which decides the delay.
F000 31 FFFE LXI SP,FEFF Define stack Pointer 2. Use the CPI instruction to compare the count with 60, & a conditional
F003 3E IB MVI A, IB Load A with 1B jump JNZ, converts this program to count only upto 59.Use the XRA
F005 30 SIM Set interrupt mask instruction to reset the accumulator to 00 after counting upto 59.
F006 FB EI Enable Interrupt
F007 06 00 MVI B, 00 Clear B Now set the delay in such a way that count advances by 1 per
F009 78 MOV A, B Load A from B second . This program coverts your MICROFRIEND DYNA – 85 into
F00A 27 DAA Decimal adjust A digital stop watch.
F00B 47 MOV B, A Load B from A 3. Write a program based on these basic ideas to display hours and
minutes in the address field and seconds in the data field. You can
F00C C5 PUSH B Save B on stack either have a 12 hour or 24 hour clock.
F00D CD 6E03 CALL MODIDT Display count
F010 16 18 MVI D, 18 Set Delay
Example 8 : FLASHING DISPLAY ‘LErn’
F012 CD F105 CALL DELAY Wait out delay
F015 C1 POP B Restore count This program flashes the message ‘Lern’ in the address field of the
F016 04 INR B Increment count dispay.
F017 C3 09F0 JMP F009 Continue
F020 3E 1F MVI A, 1F Load A with 1 F Adderss Data Mnemonic Comments
F022 30 SIM Set interrupt mask
F023 CD E702 CALL RDKBD Wait for a key to be F000 11 L
Pressed F001 0E E
F026 3E 1B MVI A, 1B Load a with 1B F002 14 r
F028 30 SIM Set interrupt mask F003 16 n
F029 FB EI Enable Interrupt F004 15 blank
F02A C9 RET Return F005 15 blank
FFCE C3 20F0 JMP F020 Jump to interrupt routine F006 15 blank

31. 5-16 5-17
Address Data Mnemonics Comments Example 9 : ROLLING DISPLAY
F010 31 FFFE LXI SP, FEFF Define stack pointer This program is included in the monitor FIRMWARE and it is accessible
F013 3E 01 MVI A, 01 Load A with 1 to use through code ‘0F’. On executing this code the display starts showing the
Data field. rolling message “dYnALOG hELPS YoU In LEArning UP”.
F015 06 00 MVI B, 00 No decimal point
F017 21 06F0 LXI, H F006 Get characters starting The rolling display is using the OUTPUT and DELAY subroutines. To
at F006H simulate the effect of rolling, characters are taken one from a string of
F01A CD B702 CALL OUTPUT Display them in data characters and the position is shifted from right to left.
field
F01D 3E 00 MVI A, 00 Use address field When the first letter appears in the highermost position, remaining 5 digits
F01F 06 00 MVI B, 00 No Decimal point must be blank.
F021 21 00F0 LXI H, F000 Get characters starting
at F000 This string starts with 5 blank characters. The last character in the string is
F024 CD B702 CALL OUTPUT Display them in address FFH, which is not used to display any letter but it is used only to detect the
Field end of string , so that the rolling can once again start from the beginning
F027 11 FFFF LXI D,FFFF Set Delay using a conditional jump instruction.
F02A CD F105 CALL DELAY Wait out delay
F02D 3E 00 MVI A, 00 The complete listing of this program is given in the FIRMWARE listing at
F02F 06 00 MVI B, 00 address 0E5BH.
F031 21 04F0 LXI H F004 Get blank
F034 CD B702 CALL OUTPUT Blank display Transfer this program from EPROM to RAM using CODE 00. Then modify
F037 11 FFFF LXI D, FFFF all the address locations suitably so that the same program can be
F03A CD F105 CALL DELAY executed form RAM.
F03D C3 1DF0 JMP F01D Continue Flashing
Now you can put any other message in the string and display that
Additional Suggestion : message.
1. Find out the location where the delay values are sorted.
Change these delay values to change the rate of flashing.
2. Select any other 4 character word and flash it on the display.
3. Select a 2 character word and place it at F004H and F005H
so that it flashes in between the flashing of 4 character word.

32. 6-1
CHAPTER 6
SERIAL I / O OPERATION
In the serial I / O section we will discuss about the RS232Ã and Audio
Cassette Interface. Apart from the Keyboard Mode, the serial Mode can be
selected with appropriate strapping. In the keyboard mode user can
communicate with the system only in hexadecimal format . The serial
mode is provided for the better interaction mode of communication using
a terminal. Normally the mode of cmmunation is ASCII ( American
Standard Code for Information Interchange).
To Correct MICROFRIEND with a terminal strap SID, the appropriate
signals are provided 7 pin cable type connect . After appropriately
connecting the terminal the standard Baud Rate is 110 with two stop bits.
When the system is powered on the in - built displays show SERIAL. This
routine expects a space character (20H in ASCII) from the terninal. The
system is claimed to be AUTO BAUD, that is after sensing the space
character from the terminal it will adjust to the appropriate Baud Rate and
hence forth communicate with this Baud Rate, until the next power ON or
the Reset key is pressed, the Baud Rate is unchanged.
Thus on power ON or Reset you press a space bar on TTY and sign on
message MICROFRIEND DYNA – 85 appears on the console . The
procedure is similsr for CRT type of terminals where the communication
mode is RS232C. RS232C is a EIA approved standard for communation.
For an active signal the channel will give -12V signal and for the inactive
signal the voltage will be +12V. This is to keep the long communication
line immune to noise and to connect a CRT terminal on RS232C link,
strap the SID line to CRT. The communication format is fully duplex, 8 bit
ASCII data , no parity start bit and two stop bits. Full Duplex means that
whatever character received from the terminal is echoed back.