struc PSP                               ; Program Segment Prefix
 pspInt20               dw ?            ; Int 20h instruction
 pspNextParagraph       dw ?            ; Segment addr of next paragraph
                        db ?            ; Reserved
 pspDispatcher          db 5 dup (?)    ; Far call to DOS
 pspTerminateVector     dd ?            ; Int 22h addr
 pspControlCVector      dd ?            ; Int 23h addr
 pspCritErrorVector     dd ?            ; Int 24h addr
                        dw 11 dup (?)   ; Reserved
 pspEnvironment         dw ?            ; Segment addr of environment
                        dw 23 dup (?)   ; Reserved
 pspFCB_1               db 16 dup (?)   ; Default FCB #1
 pspFCB_2               db 16 dup (?)   ; Default FCB #2
                        dd ?            ; Reserved
 pspCommandTail         db 128 dup (?)  ; Command tail (also default DTA)
ends                                    ; = 256d = 100h bytes

        ; The Program Segment Prefix is a control structure that
        ; DOS builds for each program. PSP occupies the first 256
        ; (100h) bytes of the memory allocated to the program.


        ; pspNextParagraph (offset 0002h in PSP)
        ; Segment address of 1st paragraph after
        ; program's memory allocation block.

        ; pspEnvironment   (offset 002Ch in PSP)
        ; Segment address of program's environment block

        ; pspCommandTail   (offset 0080h in PSP)
        ; Program's command-line arguments
        ; Format: byte length of arguments, arguments, CR character
        ;         (db 9," /s a.fil",0dh)