A Fairly Thorough Memory Addressing Resource

As Salamu Alaykum Wa Rahmatullahi Wa Barakatuh World!

As promised, today's post will not feature an algorithms resource but something different. This resource isn't even a presentation but a document that goes through all the modes of addressing that you need to know (plus relative addressing which you don't).

This resource was probably made with the old H047/H447 spec in mind but it still covers pretty much all the content needed for the new H046/H447 spec as well. As usual, the spec mentions this topic in a vague fashion by simply stating each mode of addressing you need to know (immediate, direct, indirect and indexed).

However, a closer inspection of the subject content clarification guide gives us a better understanding as to what knowledge is required:

"Candidates need an understanding of addressing, which should be integrated with assembly language. Candidates should have experience of using immediate, direct, indirect and indexed addressing in the writing, reading and tracing of programs written in assembly language." 

There's a lot going on above so let's break it down. Firstly, you need to have a general understanding of memory addressing along with all of the modes aforementioned. Secondly, just knowing the theory isn't enough, you need to integrate your understanding of memory addressing with assembly language (which you should already be familiar with before learning this. So basically, you need to be able to work with the modes of addressing mentioned whilst dealing with assembly language.

Despite being essentially a theoretical topic, memory addressing can be a bit tricky at first. However, practicing questions from past papers can greatly increase your confidence when dealing with addressing. You can find loads of addressing questions in the advanced computing theory papers of the old spec but doing the new spec questions are more worthwhile.

Being good at assembly language helps a lot in this topic so I guess this is a bit related to the practical side of things rather than the theoretical. But anyway, I recommend using the document below to gain an understanding of the topic and use The Ultimate OCR A Level Computer Science Dictionary to remind yourself of the definitions of each mode of addressing.

Here's the link: Memory Addressing Document

Hope this helps!