Clear Screen in Assembly

i mean something that will clear the "televideo terminal."..Like ike in basic there was the cls code.....is there anyhting in assembly?

I am afraid you are misunderstanding the architechure of computer and the role of CPU in that...

any even simple computing device has main CPU/MPU, and some kind of output system (also input an other parts, but this is irrelevant just now). How this output system designed and how it works depends on particular device or computer, so you may control that output by means that were given you by design (it can be access to specific port, calling of specific ROM procedure etc)

None of CPU known to me has particular single 'command' to work with video output part of you system

what is 'televideo terminal' you are reffering ? you have some working device in hands ?

You can simply fill the video buffer area with 30h (blank).
You need to know physical address of the video buffer and
video buffer structure. For example VGA has 16-bit per
screen position (8-bit character and 8-bit its attribute).

Hi ShaunnyK

In answer to your question, no, there is no assembly language instruction for clearing the screen. On some monitors, the Form Feed character, ctrl "L" ( 0Ch ) written to the output device will clear the display but for most computers, you would have to consult the technical manual for the specific display device you are driving.

Hope this helps.

EB

Er, 8085?

You're talking CP/M in all probability - haven't seen something like that in near-on 20 years!

You'd probably need to send the ANSI escape sequence for "clear screen" to the terminal, using a simple 'write string' call to the BIOS (not BDOS) system.

You're probably already using something like

   mov  C,9       ;IIRC 'write string'
   mov  HL,START  ;IIRC, HL-> start of string
   call 5         ;CP/M system call - =MSDOS INT 21

...
START: db 'string$' ; to write "string" '$' terminates

and I believe that the string required to clear the screen may be something like

esc,[,2,J

[esc = escape character, [ = open bracket, 2 and J - no commas.

Televideo was a series of serial display terminals if memory serves correctly - again, I've not seen one in nearly 20 years!

HTH

Bill

i'm presuming you have msdos on this relic ?
if so , you could use
mov ax,3
int 10h     ; clears screen and sets screen mode 3

ok here is an assembly code might help u to clear screen using interrupt 10h service. i had tried and tested it in debug program provided with windows and ms-dos

mov ax,02
mov bx,03
int 10h

I'll admit to having the mnemonics wrong.

Try:


  mvi  C,9       ;IIRC 'write string'
  lxi  HL,START  ;IIRC, HL-> start of string
  call 5         ;CP/M system call - =MSDOS INT 21

...
START: db 27,'[2J$' ; to write "string" '$' terminates


  if it's not HL,START then it's DE,START.

...Bill

Nilocb, just a little correction

All interrupts from 0 to 20h belongs to the BIOS, not the OS so interrupt 10h would work on all computers, regardless of operating system.

-BrightSide-

If your BIOS supports int 10h (video interupt)

running

mov ax, 0013h
int 13h
mov ax, 0003h
int 13h

will clear the screen in most cases.
The screen will flash twice and then be clear I believe.

It works on both my AMD and my Pentium 2 system. Hope it helps.
-Ken