IBM 5150 - Page 147

LOC OBJ
LINE
SOURCE
1816
1817
1818
; ---- INT 16 ---.-------------------- -- ----------------------------------
1819 I KEYBOARD 110
1620 I THESE ROUTINES PROVIDE KEYBOARD SUPPORT
162:1 I INPUT
1822
(AH )=0 READ THE NEXT ASCII CHARACTER STRUt:K FROM THE KEYBOARD
1823 RETURN THE RESULT IN Uli. SCAN CODE IN (AH)
1824 (AH)= 1 SET THE Z FLAG TO INDICATE IF AN ASCII CH.ARACTER IS
1825
AVAILABLE TO BE READ.
1826
(IF)=l -- NO cODE AVAILABLE
1827
(IF )=0 -- CODE IS AVAILABLE
1826 IF ZF = 0, THE NEXT CHARACTER IN THE BUFFER TO BE READ
1629 IS IN AX. AND THE ENTRY REMAINS IN THE BUFFER
1830 (AHI=2 RETURN THE CURRENT SHIFT STATUS IN AL REGISTER
1811 THE BIT SETTINGS FOR THIS CODE ARE INDICATED IN THE
1832
THE EQUATES FOR KBJLAG
1833 ; OUTPUT
1834
AS NOTED ABOVE I ONLY AX AND flAGS CHANGED
1835 ALL REGISTERS PRESERVED
1836
1----------------------------------------------------------------------.-
1837 ASSUME CS:CODE,DS:DATA
f82E
18 ..
OR'
oEa2EH
f8ZE
1839 KEYBOARD_IO PROC FAR
f82:E FB
1840
sn
; INTERRUPTS BACK ON
EeZF IE
1841
PUSH OS I SAVE CURRENT OS
E830 53
1842:
PUSH ex I SAVE BX TEMPORARILY
E831 E80A17
1843
CAll DOS
E834 OAE4
184.
OR
AH,AH
I AH=O
E836 740A
1845
JZ 01 ; ASCII_READ
E838 FEee
184. DEC AH
; AH=l
E83A 741E
1847
JZ
0'
J ASCII_STATUS
Eelt FEee 1848
DEe AH ; AH=2
£63E 742B
1849
JZ 03 ; SHIFT_STATUS
E840 EBlt
1850
JHP SHORT INTlO_END ; EXIT
1851
1852 ;----- READ THE KEY TO FIGURE OUT WHAT TO DO
1853
£842
1854 Kl: , ASCII READ
£842 FB
1855 sn ; INTERRUPTS BACK ON DUIHNG LOOP
f843 90 1856 NOP
I AllOW AN INTERRUPT TO OCCUR
E844 FA
1857
eLI
, INTERRUPTS BACK OFF
£845 8BIEl.l.OO
1858 HOY BX,BUFFER_HEAD I GET POINTER TO HEAD OF BUFFER
£849 381EICOO 1859 CHP
BX,BUFFEICTAIL
; TEST
EI'I) OF BUFFER
£840 74F3
1860
JZ
01
; LOOP UNTIL SOMEllHNG IN BUFFER
E84F 8B07
1861
HOY AX,IBX]
;
GET SCAN CODe 041'1) ASCII CODE
E651 E8}DOO
1862
CALL
04
; MOVE POINTER TO NEXT POSITION
E8S4 891ElAOO
1863
HOV
BUFFER_HEAD,ex
;
STORE VALUE IN VARIABLE
E858 EB14
1864
JHP SHORT INTIO_EHD
;
RETURN
1865
1866
1----- ASCII STATUS
1867
E85A
1868 K2:
E85A FA
1869
ell
I INTERRUPTS OFF
E85B 8BIElAOO
1870
I10Y ex,eUFFER_HEAD
;
GET HEAD POINTER
E85F 3BlEICOO
1871
CHP
Bx.eUFFER_TAIL
;
IF EQUAL (l=l' THEN NOTHING TliERE
E863 8B07
1872
HOY
Ax.(eX]
E865 FB
1873
sn
; INTERRUPTS
BACK ON
E866 56
1874
POP
ex ; RECOVER REGISTER
E867 IF
E868 tA0200
1875
1876
POP
RET
OS
,
i RECOVER SEGMENT
; THROW AWAY FLAGS
1877
1878 1----- SHIFT STATUS
1879
EMe
1880
E86B .6.01700
1881
AL.KB]LAG I GET THE SHIFT STATUS FLAGS
E66E
1882
EabE 58
1883
pop BX
; RECOVEIJ REGISTER
E86F IF
1884
POP OS
I RECOVER REGISTERS
E870 CF
1885
IRET
;
RETlJRN TO CALLER
1886-
KEYBOARD_IO ENDP
1887
1888
;----- INCREMENT A eUFfER POINTER
1889
Ee71
1890 04 PROC NEAR
£871 43
1891
INC ax
I MOVE TO NEXT WORD IN LIST
E872 43
1892
INC ex
5-54 System BIOS