Hmm, sorry for the disappearance, but its working now.
The problem seems to be a combination of a bad cable and a missing capacitor.
My homemade serial cable made from an old serial mouse cable apparently has broken links within the cable which made things go crazy. Using the cable off another old mouse gave me more consistent results.
Things were still not operating as they're supposed to though. After looking through the typical operating diagram for the MAX233, I remembered that I omitted the 1.0uF capacitor required between Vcc and GND. Things worked straight away after I added that capacitor.
Then a question came to my head. The chip's specifications stated 0 external capacitors required, which is why I thought I could omit the 1.0uF capacitor. Did I forget to read some fine print regarding their capacitor count?
And in the interest of learning, I have three questions.
What is the purpose of that capacitor; is it for filtering purposes or as a "power reserve" during current draw peaks?
If it is not there to act as a noise filter and since I already have an output capacitor attached to my voltage regulator's output, can I just "merge" the two capacitors (i.e. Remove both capacitors and replace with one with a value of the sum of the two capacitors removed)? They are (I think) in effect capacitors attached in parallel and should be equivalent to a single capacitor with a capacitance equal to the sum of the capacitance of the capacitors attached in parallel?
What effect does this new capacitor added have on the time taken for the power supply to stabilise on power up?
Sorry if my questions sound confusing, illogical, weird and/or stupid, I'm in the beginning stages of my learning and things are still shaky.
Also, please look at this other thread that I have started for some questions on a project I'm working on:
Very much appreciated!