diff --git a/kernel/parse.asm b/kernel/parse.asm
index 1bd81b2..3935e31 100644
--- a/kernel/parse.asm
+++ b/kernel/parse.asm
@@ -11,26 +11,16 @@
 ; On success, the carry flag is reset. On error, it is set.
 parseHex:
 	; First, let's see if we have an easy 0-9 case
-	cp	'0'
-	jr	c, .error	; if < '0', we have a problem
-	cp	'9'+1
-	jr	nc, .alpha	; if >= '9'+1, we might have alpha
-	; We are in the 0-9 range
-	sub	'0'		; C is clear
-	ret
+	
+	add 	a, 0xc6	; maps '0'-'9' onto 0xf6-0xff
+	sub 	0xf6	; maps to 0-9 and carries if not a digit
+	ret	nc
 
-.alpha:
-	call	upcase
-	cp	'A'
-	jr	c, .error	; if < 'A', we have a problem
-	cp	'F'+1
-	jr	nc, .error	; if >= 'F', we have a problem
-	; We have alpha.
-	sub	'A'-10		; C is clear
-	ret
-
-.error:
-	scf
+	and 	0xdf		; converts lowercase to uppercase
+	add	a, 0xe9		; map 0x11-x017 onto 0xFA - 0xFF
+	sub 	0xfa		; map onto 0-6
+	ret 	c
+	add	a, 10		; C is clear, map back to 0xA-0xF
 	ret
 
 ; Parses 2 characters of the string pointed to by HL and returns the numerical
@@ -39,34 +29,35 @@ parseHex:
 ; HL is set to point to the last char of the pair.
 ;
 ; On success, the carry flag is reset. On error, it is set.
-parseHexPair:
-	push	bc
 
-	ld	a, (hl)
-	call	parseHex
-	jr	c, .end		; error? goto end, keeping the C flag on
-	rla \ rla \ rla \ rla	; let's push this in MSB
-	ld	b, a
-	inc	hl
-	ld	a, (hl)
-	cp	0x21
-	jr	c, .single	; special char? single digit
-	call	parseHex
-	jr	c, .end		; error?
-	or	b		; join left-shifted + new. we're done!
-	; C flag was set on parseHex and is necessarily clear at this point
-	jr	.end
 
-.single:
-	; If we have a single digit, our result is already stored in B, but
-	; we have to right-shift it back.
-	ld	a, b
-	and	0xf0
-	rra \ rra \ rra \ rra
-	dec	hl
+parseHexPair:	; 31 bytes, 78 cycles
+	ld 	a, (hl)
+	call 	parseHex
+	ret 	c		; faster and smaller than a conditional jump
+; by delaying this push, we can use a conditional return above
+	push 	bc		
+	ld 	b, a
+	inc 	hl
+	ld 	a, (hl)
+	cp 	0x21
+	jr 	c, .single
+	call 	parseHex
+	jr 	c, .end
+	ld 	c, a
+	ld 	a, b
+	; by delaying shifting until the end, we save bytes in the single case.
+	rla \ rla \ rla \ rla	
+	or 	c
 
-.end:
-	pop	bc
+	.end:
+	pop 	bc
+	ret
+
+	.single:	;53 cycles if single
+	ld 	a, b
+	dec 	hl
+	pop 	bc
 	ret
 
 ; Parse arguments at (HL) with specifiers at (DE) into (IX).
@@ -86,6 +77,7 @@ parseHexPair:
 ;                          be placed in the next two bytes. This has to be the
 ;                          last argument of the list and it stops parsing.
 ; Sets A to nonzero if there was an error during parsing, zero otherwise.
+
 parseArgs:
 	push	bc
 	push	de
diff --git a/kernel/sdc.asm b/kernel/sdc.asm
index 6cd00c6..1b63214 100644
--- a/kernel/sdc.asm
+++ b/kernel/sdc.asm
@@ -85,14 +85,13 @@
 
 ; *** Code ***
 ; Wake the SD card up. After power up, a SD card has to receive at least 74
-; dummy clocks with CS and DI high. We send 80.
+; dummy clocks with CS and DI high. We send (way more than) 80.
 sdcWakeUp:
 	out	(SDC_PORT_CSHIGH), a
-	ld	b, 10		; 10 * 8 == 80
+	ld	b, 10		; 10 * 11 == 110
 	ld	a, 0xff
 .loop:
 	out	(SDC_PORT_SPI), a
-	nop
 	djnz	.loop
 	ret
 
@@ -100,11 +99,9 @@ sdcWakeUp:
 ; is placed in A.
 sdcSendRecv:
 	out	(SDC_PORT_SPI), a
-	nop
-	nop
+	push 	hl		; nop, pairs with pop later
 	in	a, (SDC_PORT_SPI)
-	nop
-	nop
+	pop	hl		; nop, pairs with earlier push
 	ret
 
 sdcIdle: