840369k@aucs.UUCP (Elric Kinslayer) (03/13/89)
I'm writing a realtime application which runs a robot arm by reading
characters from the keyboard. The problem is that too many commands
get "queued" into the keyboard buffer. What's a quick and easy way
(assembly , turbo-pascal, or just poking memory) to clear the
keyboard? Net people with memory maps, any ideas?
Thanks in advance,
Kelly.
P.S. The "PC compatible" is a Tandy 1000, if it helps.
--
-------------------------------------------------------------------------------
| Kelly Kendrick Acadia University, N.S. | "And now GROO does |
| {seismo|watmath|utai|garfield}!dalcs!aucs!840369k | what GROO does best!" |
-------------------------------------------------------------------------------todd@stiatl.UUCP (Todd Merriman) (03/15/89)
In article <1636@aucs.UUCP> 840369k@aucs.UUCP (Elric Kinslayer) writes: >What's a quick and easy way to clear the keyboard? > ifdef DOCUMENTATION ; **************************************************************************** CONFLUSH.ASM 2/17/89 Todd Merriman .MODULE conflush .LIBRARY csub .TYPE function .DESCRIPTION Flush the type-ahead buffer .ARGUMENTS void conflush() .NARRATIVE Conflush drains the type-ahead buffer. All the characters in the buffer are thrown away. .APPLICATION system .SYSTEM msdos .AUTHOR Todd Merriman .RETURNS Nothing .LANGUAGE MSDOS small model & VMS, Assembly; all others, C .ENDOC END DOCUMENTATION ; **************************************************************************** endif INCLUDE \HEADER\C.MAC ; symbols and macros for Microsoft PSEG ; begin program section CFUN conflush PUSH BP MOV AX,0C00H ; flush buffer system call INT 21H POP BP RET CFEND conflush ENDPS ; end program section END ; **************************************************************************** ; End CONFLUSH.ASM ; **************************************************************************** ...!gatech!stiatl!todd Todd Merriman 404-377-8638 Atlanta, GA
jmv@sppy00.UUCP (Jim Vickroy) (03/15/89)
In article <1636@aucs.UUCP> 840369k@aucs.UUCP (Elric Kinslayer) writes:
=>get "queued" into the keyboard buffer. What's a quick and easy way
=>(assembly , turbo-pascal, or just poking memory) to clear the
=>keyboard? Net people with memory maps, any ideas?
=>
I'm not sure this is neither quick nor easy but here goes:
I am referencing the IBM Hardware Technical Reference: System BIOS (version
2.02)
Set up a segment at 40H and setup your own BUFFER_HEAD and BUFFER_TAIL
at offset 1AH and 1CH
Setup your own BUFFER_START and BUFFER_END at offset 80H and 82H
;
; Reset Keyboard
;
MOV AX,BUFFER_START
MOV BUFFER_HEAD,AX
There is an interrupt function to reset the extended keyboard, however it
escapes me at the moment (I'm responding from home and won't be in the office
for a week). If no one responds by the time I return, I'll post the method. I
do remember I did it in C.
Good luck.
jim
--
!==================================================================!=========!
! Jim Vickroy | cbosgd!osu-cis!sppy00!jmv !/././././!
! Online Computer Library Center, Inc. |---------------------------!././././.!
! Dublin, Ohio 43017 | jmv@sppy00 !/././././!
!------------------------------------------------------------------!././././.!
! "That voodoo stuff don't do nothin' for me" -jrr !/././././!
!==================================================================!=========!
bobmon@iuvax.cs.indiana.edu (RAMontante) (03/21/89)
If you're using Turbo-Pascal, you should have a "kbhit()" function to tell you whether any keys are queued, and a "kbread()" or something similar to get those keys. Turbo-C uses these, and I vaguely remember something like this from TPascal v3. You need the kbhit() test because kbread() (or whatever it's called) will wait until it does get a key.