Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 16)

16 CHAPTER 2. INTRODUCTION TO LOOPING

2.2.1 The function OUTA

The function OUTA will transmit whatever is in register A over the serial com-

munication line that is connected to the PC. What the PC does with this value

depends on the terminal program that is used to communicate with the HC11.

Under normal circumstances, the terminal program will interpret the value as an

ASCII code and display the corresponding character on the screen.

Exercise: Power up HC11 and at the BUFFALO prompt try the following and

write down what you see.

1. Issue the command RM (for register modify) and press the space bar till

you see the A register. Enter the value 31 and press enter as shown below:

>rm

P-AAAA Y-AAAA X-AAAA A-AA B-AA C-D0 S-004A

P-AAAA

Y-AAAA

X-AAAA

A-AA 31

Now execute the command

CALL FFB8

2. Repeat with the A register modiﬁed with the following values: 32, 33,

34, 21, 22, 23, 24, 25, 41, 42 43 44

If you are using the simulator, turn on the log feature (by pressing both the shift

keys). If you are working with a real HC11, you can copy and paste the contents

of the terminal screen.

2.2.2 The function OUT1BYT

This is a more involved output function. To start with, the value to be printed

must b e in memory. If the value is in a register you will have to store it in

memory ﬁrst. Next, the value in the X register should be the address where the

value is stored. Thus this function should be told ’where’ and not ’what’. When

you call this function, the function will send two characters to the PC. If the

terminal program interprets these two characters as ASCII codes and displays

the corresponding two characters, then the display would be the value written in

HEX. In addition, the function will increment the value in the X register. This is

useful when displaying a series of memory locations.

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 100 101

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Motorola Axiom CMD11E1 Guía de usuario Pagina 16