Assembly Language Program to Print First Name

Question

I am trying to write an assembly language program that prints a first name--e.g., Thomas. It is supposed to use the .ASCII pseudo-operation to store the characters at the bottom of the program, and the CHARO instruction to output the characters. When I look at an example in the textbook:

;Stan Warford

;January 13, 2009

;A program to output "Hi"

;

CHARO   0x0007,d   ;Output 'H'

CHARO   0x0008,d   ;Output 'i'

STOP  

.ASCII  "Hi"

.END

This outputs "Hi" correctly. However, when I try to write a program that outputs
Thomas, it doesn't work. What I have:

CHARO       0x0004 ,d   ;output T
CHARO       0x0005 ,d   ;output h
CHARO       0x0006 ,d   ;output o
CHARO       0x0007 ,d   ;output m
CHARO       0x0008 ,d   ;output a
CHARO       0x0009 ,d   ;output s
STOP
.ASCII      "Thomas"
.END

When I run this, nothing is being output to the screen. I am trying to run this on the Pep/8 simulator. Am I missing something really obvious here? Is there a specific hex value I need to start with when using the CHARO commands--e.g., 0x0007? Thanks in advance for the advice.

Iłya Bursov · Answer 1 · 2016-03-08T01:44:56.607

1

I haven't ever used pep8, but according to docs, these variants will work:

CHARO       0x0013,d
CHARO       0x0014,d
CHARO       0x0015,d
CHARO       0x0016,d
CHARO       0x0017,d
CHARO       0x0018,d
STOP
.ASCII      "Thomas"
.END

or:

CHARO   'T',i
CHARO   'h',i
CHARO   'o',i
CHARO   'm',i
CHARO   'a',i
CHARO   's',i
STOP  

.END

or

STRO msg,d
STOP
msg: .ASCII "Thomas\x00"
.END

edited Mar 08 '16 at 01:44

answered Mar 08 '16 at 01:29

Iłya Bursov

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Thank you for that. Perhaps a dumb question here...but for the first variation you suggested, why must it start with 0x0010 ,d? – ComputerScientist123 Mar 08 '16 at 01:31
0x10 - is the address of first letter `T` – Iłya Bursov Mar 08 '16 at 01:32
I tried it on the simulator, and it only prints `Tho`. Very strange. – ComputerScientist123 Mar 08 '16 at 01:33
I also tried it with a different ASCII string, and it still only prints the first three characters, no matter what the string is. – ComputerScientist123 Mar 08 '16 at 01:37
@CSstudent actually strange, let me download and check – Iłya Bursov Mar 08 '16 at 01:41
It must be something to do with the addressing, because the book starts with 0x0004 for 'H.' I know the 0x is supposed to show that the representation is in hex, but 0004 is not the hex value for H. @Lashane – ComputerScientist123 Mar 08 '16 at 01:43
@CSstudent yeah, I calculated wrong offset, it should start at 0x13, not 0x10 – Iłya Bursov Mar 08 '16 at 01:45
Can we continue in chat? @Lashane – ComputerScientist123 Mar 08 '16 at 01:47
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/105621/discussion-between-csstudent-and-lashane). – ComputerScientist123 Mar 08 '16 at 01:47

score 0 · Accepted Answer · answered May 14 '16 at 01:31

This is the correct code, using the name "Miranda" as an example:

    CHARO 0x0016 ,d ;output M
    CHARO 0x0017 ,d ;output i
    CHARO 0x0018 ,d ;output r
    CHARO 0x0019 ,d ;output a
    CHARO 0x001a ,d ;output n
    CHARO 0x001b ,d ;output d
    CHARO 0x001c ,d ;output a
    STOP
    .ASCII "Miranda"
    .END

Assembly Language Program to Print First Name

2 Answers2