SD (software-defined) radio receivers use a bare minimum of hardware, relying instead on their software capabilities. This SDR project demonstrates what’s achievable, in this case a multi-purpose receiver covering all bands from 150 kHz to 30 MHz. It’s been optimised for receiving DRM and AM broadcasts but is also suitable for listening in to the world of amateur transmissions.

www.nti-online.de/diraboxsdr.htm
www.sdradio.org
sourceforge.net/projects/drm
www.g8jcf.dyndns.org

.nolist			; We don't want to actually include defs in our listing file.
.include "m168def.inc"	; m168def.inc defines all the pins on the Mega168 so we can
			; use them by their names rather than addresses (not fun).

.list			; We DO want to include the following code in our listing ;D

	rjmp	main 	; You usually place these two lines after all your
main:			; directives. They make sure that resets work correctly.

	ldi	r16,0xFF ; LoaD Immediate. This sets r16 = 0xFF (255)
	out	DDRB,r16 ; Out writes to SRAM, which is one way of accessing
			 ; pins. DDRB controls PORTB's in/out state.

	ldi	r16,0x00 ; r16 is where we'll store current LED state
			 ; 0x00 means all off. This is preserved over loops.

; LEDblink.asm - M. Covington 2006 
; For ATtiny13. 
; Blinks the LEDs attached to PB0 and PB1. 

.include "tn13def.inc" 

.def temp = R16 
.def temp1 = R17 
.def temp2 = R18 
.def mask = R19 

start: ldi temp,0b00000010
       out PORTB,temp ; initialize port B 
       ser mask 
       out DDRB,mask ; port B all outputs 
blink: 
       ; Delay 0.1 sec (1.2 MHz) 
       ldi temp1,200 ; outer loop count 
L1:    ldi temp2,199 ; inner loop count 
L2:    dec temp2 
       brne L2 
       dec temp1 
       brne L1 
       ; Toggle PB0 and PB1 
       ldi mask,0b00000011 
       eor temp,mask 
       out PORTB,temp 

       rjmp blink 
; End of program

Some characteristics, however, show refinement over what Apple has done. The Pre's processor board is "substantially" smaller than the iPhone's and reveals that Palm spent a large amount of time maximizing its available space -- a particular feat given the faster, 600MHz Texas Instruments OMAP3 processor and newer PowerVR SGX 530 graphics. Enough seems familiar that iFixit draws a close parallel between the two companies.

The Pre's main components exposed but still assembled; a water damage sensor is highlighted on the left. | Image credits: iFixit.

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% /home/cs1721/bin/emu /home/cs1721/public_html/05s2/emu/examples/iota.hex
Emu Reference Implementation v0.?
> program
0000: e000 LDI R16,0
0001: e081 LDI R24,1
0002: 2fa0 MOV R26,R16
0003: e7f0 LDI R31,112
0004: e0e0 LDI R30,0
0005: 9509 ICALL
0006: e011 LDI R17,1
0007: 0f01 ADD R16,R17
0008: e614 LDI R17,100
0009: 1b10 SUB R17,R16
000a: f7b1 BRBC 1,-10
000b: e080 LDI R24,0
000c: e7f0 LDI R31,112
000d: e0e0 LDI R30,0
000e: 9509 ICALL
> registers
PC=0000 SP=1100 SR=[C=0,Z=0,N=0,V=0]
r00-r0f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
r10-r1f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> step
0000: e000 LDI R16,0
PC=0001 SP=1100 SR=[C=0,Z=0,N=0,V=0]
r00-r0f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
r10-r1f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> run
0
1
...
8
9
> restart
> run
0
1
...
9
> registers
PC=000f SP=1100 SR=[C=0,Z=1,N=0,V=0]
r00-r0f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
r10-r1f 0a 00 00 00 00 00 00 00 00 00 09 00 00 00 00 70

Example: sum of first 4 integers.

sum = 0;
for (i = 1; i <= 4; ++i)
   sum += i*i;

sum = 0;
i = 1;
loop:
   if (i == 5) goto end;;
   sum = sum + i;
   i = i + 1;
goto loop;
end:

; sum in R16
; i in R17
; R18,R19 used for temporary values
    LDI R16, 0
    LDI R17, 1
    LDI R18, 5
    SUB R18, R17
    BRBS 1, 22
    ADD R16, R17
    LDI R19, 1
    ADD R17, R19
    JMP 2
    SLEEP