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pcat: use heads count from 13H08H

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On real hardware, there aren't always 2 heads...
This commit is contained in:
Virgil Dupras 2020-06-22 05:59:26 -04:00
parent d7f002df98
commit 515890717f
1 changed files with 9 additions and 5 deletions
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14
recipes/pcat/xcomp.fs
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@ -12,10 +12,11 @@ CODE (emit) 1 chkPS,
CODE (key)
AH AH XORrr, 0x16 INT, AH AH XORrr, AX PUSHx,
;CODE
CODE 13H08H ( driveno -- cx )
CODE 13H08H ( driveno -- cx dx )
DI POPx, DX PUSHx, ( protect ) DX DI MOVxx, AX 0x800 MOVxI,
DI DI XORxx, ES DI MOVsx,
0x13 INT, DX POPx, ( unprotect ) CX PUSHx,
0x13 INT, DI DX MOVxx, DX POPx, ( unprotect )
CX PUSHx, DI PUSHx,
DI 0x800 MOVxI, ES DI MOVsx,
;CODE
CODE 13H ( ax bx cx dx -- ax bx cx dx )
@ -25,12 +26,13 @@ CODE 13H ( ax bx cx dx -- ax bx cx dx )
AX PUSHx, BX PUSHx, CX PUSHx, SI PUSHx,
;CODE
: FDSPT 0x70 RAM+ ;
: FDHEADS 0x71 RAM+ ;
: _ ( dest secno )
( AH=read sectors, AL=1 sector, BX=dest,
CH=trackno CL=secno DH=head DL=drive )
0x0201 ROT ROT ( AX BX sec )
FDSPT @ /MOD ( AX BX sec trk )
2 /MOD ( AX BX sec head trk )
FDSPT C@ /MOD ( AX BX sec trk )
FDHEADS C@ /MOD ( AX BX sec head trk )
8 LSHIFT ROT OR 1+ ( AX BX head CX )
SWAP 8 LSHIFT 0x03 C@ ( boot drive ) OR ( AX BX CX DX )
13H 2DROP 2DROP
@ -41,7 +43,9 @@ CODE 13H ( ax bx cx dx -- ax bx cx dx )
: FD! DROP ;
: FD$
( get number of sectors per track with command 08H. )
0x03 ( boot drive ) C@ 13H08H 0x3f AND FDSPT !
0x03 ( boot drive ) C@ 13H08H
8 RSHIFT 1+ FDHEADS C!
0x3f AND FDSPT C!
;
380 LOAD ( xcomp core high )
(entry) _