2-bit paper processor teaches how they work
posted Sep 23rd 2010 9:47am by Mike Szczysfiled under: misc hacks
Take a few minutes out of your day, grab your scissors, and learn how a simple processor works. [Saito Yutaka] put together an exercise to teach processor operations with paper. After downloading the PDF you can cut out the Address and Data pointer as well as two-bit data tokens for each. The processor has three instruction sets; Increment register by one, Jump if not over flow, and Halt wait for reset.
Once you’ve got your cutouts you can follow along as the program is executed. The INC operation is run, with the JNO used to loop the program. Once the register has reached an overflow the overflow counter halts the program.
One word of warning, we think there’s a typo in one of the captions. Once the program starts running and gets to address 01(2) the caption still reads 00(2) for both address and data. As long as you compare the values in the picture along the way you should have no problem getting through execution. which has now been fixed.
This reminds of the the Bell Labs CARDIAC, a similar concept but base 10. I had one when I was 9 or 10. Later I found a stash of them and bought a few but I believe they may all be gone now; at least, the web site on AOL is gone. But here’s a mirror:
http://www.porticus.org/bell/belllabs_kits.html