Code reduction suggestion

You can remove two 'jmp PutChar' (4 bytes) :
```diff
--- sectorlisp.S
+++ sectorlisp.S
@@ -67,7 +67,9 @@
jbe 2f
stosb
xchg %ax,%si
-2: call GetChar # exchanges dx and ax
+2: xor %ax,%ax # GetChar→al:dl
+ int $0x16 # get keystroke
+ call PutChar # exchanges dx and ax
cmp $' ',%al
jbe 1b
cmp $')',%al
@@ -90,8 +92,14 @@
jz 4f # jump if nil
mov $249,%al # bullet (A∙B)
call .PutObject
-4: mov $')',%al
- jmp PutChar
+4: mov $'\r'^'\n'^')',%al
+PutLf: xor $'\r'^'\n',%al
+PutChar:mov $0x0e,%ah # prints CP-437
+ int $0x10 # vidya service
+ cmp $'\r',%al # don't clobber
+ je PutLf # look xchg ret
+ xchg %dx,%ax
+ ret

.PutObject: # .PutObject(c:al,x:si)
.PrintString: # nul-terminated in si
@@ -132,17 +140,6 @@
9: pop %cx
ret

-GetChar:xor %ax,%ax # GetChar→al:dl
- int $0x16 # get keystroke
-PutChar:mov $0x0e,%ah # prints CP-437
- int $0x10 # vidya service
- cmp $'\r',%al # don't clobber
- jne .RetDx # look xchg ret
- mov $'\n',%al
- jmp PutChar
-.RetDx: xchg %dx,%ax
- ret
-
////////////////////////////////////////////////////////////////////////////////

Evlis: test %di,%di # Evlis(m:di,a:dx):ax
```
And inline Cadr (2 bytes):
```diff
--- sectorlisp.S
+++ sectorlisp.S
@@ -233,8 +230,6 @@
mov (%bx,%si),%si
scasw
jne 1b
- .byte 0xF6 # testb §i8,i16(%bp,%di) jmp Car
-Cadr: mov (%bx,%di),%di # contents of decrement register
.byte 0x3C # cmp §scasw,%al (nop next byte)
Cdr: scasw # increments our data index by 2
Car: mov (%di),%ax # contents of address register!!
@@ -250,7 +245,8 @@
jz 1b
push (%di) # push Car(c)
.EvCadr:pop %di
- call Cadr # ax = Cadar(c)
+ mov (%bx,%di),%di
+ mov (%di),%ax # ax = Cadar(c)
# jmp Eval

Eval: test %ax,%ax # Eval(e:ax,a:dx):ax
```

Start with sectorlisp.S and inspect GetChar, PutChar, Cadr, and .EvCadr, including their calling and register conventions. Review the proposed inlining and removals, then verify that the boot-sector code retains its input, output, and Cadr behavior while achieving the stated byte reductions.

Written by the indexing model from the issue text.