1 files changed, 54 insertions, 0 deletions

diff --git a/v4.0/src/MAPPER/SEL_DISK.ASM b/v4.0/src/MAPPER/SEL_DISK.ASM
new file mode 100644
index 0000000..ab3bbc9
--- /dev/null
+++ b/v4.0/src/MAPPER/SEL_DISK.ASM
@@ -0,0 +1,54 @@
+;
+page 80,132
+;
+title CP/DOS DosSelectDisk mapper
+;
+dosxxx  segment byte public 'dos'
+        assume  cs:dosxxx,ds:nothing,es:nothing,ss:nothing
+;
+;**********************************************************************
+;*
+;*   MODULE:   dosselectdisk
+;*
+;*   FILE NAME: dos048.asm
+;*
+;*   CALLING SEQUENCE:
+;*
+;*       push      word  drive          drive number
+;*       call      dosselectdisk
+;*
+;*   MODULES CALLED:  PC-DOS Int 21h, ah=0eh, select disk
+;*
+;*********************************************************************
+
+            public   dosselectdisk
+            .sall
+            .xlist
+            include  macros.inc
+            .list
+
+str         struc
+old_bp      dw       ?
+Return      dd       ?
+Drive       dw       ?       ; drive number
+str         ends
+
+dosselectdisk  proc  far
+        Enter   Dosselectdisk         ; push registers
+
+        mov     dx,[bp].drive         ; load drive number
+        dec     dx                    ; adjust for cp/dos incompatibility
+
+        mov     ah,0eh
+        int     21h                   ; select the drive
+
+        sub     ax,ax                 ; set good return code
+
+        mexit                         ; pop registers
+        ret     size str - 6          ; return
+
+dosselectdisk endp
+
+dosxxx      ends
+
+            end