Learning PASM
SciNemo
Posts: 91
I have been learning to program computers for something like 9 years now, but I've only really worked with high level languages. I've always shied away from assembly because its been described to me as very difficult to learn. Recently I found a book in my school library (a 30 year old book 
) that teaches you assembly (specifically for a really old Motorola microcomputer). I've been reading it, and it's been amazing. So many gaps in my knowledge of the inner workings of computers have been filled in. Still, I can't really use the assembly stuff I'm learning because the micro in the book is very old and outdated.
I was wondering where someone would start learning PASM, what kind of projects to start with, and whether it is possible that I might destroy my beloved demo board by messing around with this. Please keep in mind that I am 15 years old and have no direct experience with the early days of computers that everyone here seems to be very close to (and still trying to get back to
).
Any helpful thoughts are welcome.
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Not the fish.
sites.google.com/site/bitwinproject/
) that teaches you assembly (specifically for a really old Motorola microcomputer). I've been reading it, and it's been amazing. So many gaps in my knowledge of the inner workings of computers have been filled in. Still, I can't really use the assembly stuff I'm learning because the micro in the book is very old and outdated.I was wondering where someone would start learning PASM, what kind of projects to start with, and whether it is possible that I might destroy my beloved demo board by messing around with this. Please keep in mind that I am 15 years old and have no direct experience with the early days of computers that everyone here seems to be very close to (and still trying to get back to
).Any helpful thoughts are welcome.
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Not the fish.
sites.google.com/site/bitwinproject/
Comments
Just go through the obex and look how something is done in a driver. Once you understand how the driver works, write your own version of it from scratch.
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Nyamekye,
http://forums.parallax.com/attachment.php?attachmentid=58857
Assembly Code Examples for the Beginner
http://forums.parallax.com/showthread.php?p=601870
Quick Reference Guide for Propeller Assembly
http://forums.parallax.com/attachment.php?attachmentid=44331
Programming the Parallax Propeller using Machine Language
An intermediate level tutorial by deSilva © 2007
Version 1.21 2007-08-21
http://forums.parallax.com/attachment.php?attachmentid=48819
Wikispaces /Assembly+Programming
propeller.wikispaces.com/Assembly+Programming
Assembler for the Parallax Propeller
www.cliff.biffle.org/software/propeller/propasm/
Propeller Assembler Source-code Debugger
propeller.wikispaces.com/PASD
How is RES different from LONG?
propeller.wikispaces.com/LONG+vs+RES
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Aka: CosmicBob
http://iiusaedu.com/~murdocca/POCA/slides/
Just found it this day and copied all the PDFs even if I deal with Microprocessors and Assembler since more than 20 years. It's a good start to learn about the internals of a processor before starting with a special assembler dialect.
May I ask which micro?
The micro may be outdated -- one of my first micros was the 6809 -- but things I learned with it and the Z-80 came in handy for the 6502, 8085, COP-8, 8051, etc., etc., etc. all the way up to the PIC, the AVR, and the Propeller. For instance, the index registers in the 6809 made the concept of C's pointers click into place when I realized "Pointers are just like the Index Registers!"
Good Luck,
--Rich
I get what you mean about the ideas carrying over (and that flow of ideas makes me feel warm and fuzzy inside
Thank you so much for all the info, I have a feeling it is going to take longer than the time it takes to read the book to digest all this info.
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Not the fish.
sites.google.com/site/bitwinproject/
Kye,
I have to admit, most people may find going through other peoples code helpful, but I found parts of it confusing. This does depend on what code chosen to be the tutor.
I was looking at Mike Green's I2C driver and it was just baffling me. I had to actually have another member (you know who you are) step me through the parts which were giving me trouble. The commands themselves made a lot of sense, it was passing of variables which was a major problem for me. But I have played with the propeller for a long time, which probably helped.
As a side note, why do certain people always jump into a project which is beyond complicated. I have a tendency to do this myself, but do not understand why. I figure it is due to what I'm trying to accomplish, and it is never simple. Oh well, I learn a lot during the process, even though sometimes I feel like destroying every computer I see, from frustration.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
"Jumping" into projects that aren't complicated is boring, since you already know how to do all of it. That's what work is...
I just wish I would jump into a project that didn't take me months or years to complete. It really gets to be old after a while. I do have some neat projects. Just wish I could get one or some of them finished.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Here is what I'm trying as a first project:
Modify the code for the microphone to vga program that was made a while ago so that a screen of cyan (or white if I want) alternates with a screen of black. I've sort of dissected the original code, and took out what I thought I didn't need, which resulted in this skeleton code (only asm, rest is not included):
DAT org asm_entry mov xpos,#0 mov asm_cnt,cnt 'prepare for WAITCNT loop add asm_cnt,asm_cycles :loop waitcnt asm_cnt,asm_cycles 'wait for next CNT value (timing is determinant after WAITCNT) ' Plot plot mov asm_mask,#1 'compute pixel mask shl asm_mask,x shl y,#6 'compute pixel address add y,asm_pixels shr x,#5 shl x,#2 add y,x rdlong asm_data,y 'xor pixel xor asm_data,asm_mask wrlong asm_data,y plot_ret ret ' ' ' Data ' asm_dira long $00000200 'output mask asm_pixels long 0 'pixel base (set at runtime) mode long 0 asm_cycles long |< bits - 1 asm_data res 1 asm_mask res 1 asm_cnt res 1 xpos res 1 x res 1 y res 1Now what I think I want to do is alternately fill the screen buffer (located at the asm_pixels pointer) with 1s and 0s. I'm at a loss of where to start. I think the first order of business is making some code that shifts through every x and y address, with calls to the plot sub routine inside the loop. That way the code can just be pasted twice (one for filling with 1s, and the other for the 0s) to get what I want.
Are all my assumptions right, and is this a good place to start PASM?
Btw, I know it would cause some serious seizures because of the speed of execution, but I am guessing that modifying the value in asm_cycles will remedy that.
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Not the fish.
sites.google.com/site/bitwinproject/