I've restructured the alternative version of PDP-7 Unix so that the

source code is now in src/alt. All the files in src/sys and src/cmd
are only annotated versions of the files in scans/.
The build/Makefile has been updated so that it can build the
original PDP-7 Unix or the alternative version.
Phil has fixed the Graphics-2 code, so that there is no need to
have any #ifdef code in the original kernel.

src/sys/s2.s

@@ -6,11 +6,6 @@
 	"   sys status; dir_name_ptr; file_name_ptr
 	"   NO_DD version: sys status; file_name_ptr
 .status:
-#ifdef NO_DD
-   jms arg			" fetch file name pointer
-   dac .+3
-   lac u.cdir			" get current working directory
-#else
    jms arg			" fetch directory name pointer
    dac .+5
    jms arg			" fetch file name pointer
@@ -18,7 +13,6 @@
    lac u.cdir			" get current working directory
    jms namei; ..		" look up source directory
       jms error			"  not found: return error to user
-#endif
    jms namei; ..		" look up file
       jms error			"  not found: return error
    jms iget			" read file inode
@@ -110,11 +104,7 @@
    dac 1f
    jms arg
    dac 2f
-#ifdef NO_DD
-   lac u.cdir			" Search the current directory
-#else
    lac d4			" Search the directory at i-num 4
-#endif
    jms namei; 0:0		" for the first argument
       jms error			" Didn't find it
    jms namei; 1:0		" In the i-num found by 1st namei,

src/sys/s7.s

@@ -4,8 +4,6 @@
 pibreak:			" priority interrupt break processing "chain"
    dac .ac			" save interrupt AC
 	"** CROSSED OUT....
-
-#ifdef GRAPHICS2
    dpsf
    jmp 1f		" disable the Graphics-2 I/O
 
@@ -26,7 +24,6 @@ pibreak:			" priority interrupt break processing "chain"
    -1
    dac dpwrite
    jmp piret	"** END OF CROSSOUT
-#endif
 
 1: clsf			" clock overflow (line frequency ticks)?
    jmp 1f		"  no
@@ -90,7 +87,6 @@ cnop:			" fetched as constant in iread
    dac .dspb
    jmp piret
 dsprestart:
-#ifdef GRAPHICS2
    lac d1
    dac .dspb			" set .dsbp = 1
    lac dspbufp			" load display buf pointer
@@ -109,7 +105,6 @@ dsprestart:
    dac .lpba			" save
    rlpd				" G-2: resume after light pen stop
    jmp piret
-#endif
 
 1: ksf				" (TTY) keyboard flag set?
    jmp 1f			"  no