Hello fellas.
Welcome back.
In these next three lessons we shall look at some of the core extensions that can be placed next to
the core.
These extensions improve performance manage resources and provide extra functionalities and and are
designed to provide flexibility in handling particular applications.
Each family has different extensions available to it.
The are hardware extension is wraps on the call.
In this lesson we shall take a look at the very first one which is the cash and tightly coupled memory.
As I've mentioned earlier the cash is a block of fast memory place between the core and the main memory.
It allows for more efficient features from some memory types with a cash.
The process of call can run for majority of the time without having to wait for data from slow external
memory.
Most based embedded systems use a a single level cash internal to the process or has two forms of this
fast accessible memory.
The first form is used with the with von Neumann architecture and this form which we are currently looking
at combines both data and instruction into a single unified cash load and control an amber bus interface
unit simply helps connect to the memory system to the Amber bus which connects to the main memory.
The second reform of fast accessible memory use with the use by arm is used with the Harvard architecture
and this form has separate fast accessible memories for data and instruction.
And as you may recall the cash provides an overall increase in performance but at the expense of predictable
execution real time systems are deterministic systems they require execution time to be predictable.
This can be achieved using this second form of fast accessible memory caught the tightly coupled memory
or the TCM to TCM is a first s room located close to the core and guarantees that clock cycles required
to fetch instructions or data to set up here as memory and address map and can be accessed very fast.
So in effect they work like the cash effect by using the teams and the cash processors have both extra
performers boost their now predictable real time response.
This is what the modified architecture looks like.
The logic and control unit is placed between the police between the memory management unit and the core
and the memory management units.
I mean as the the data TCM is structured TCM data cache instruction cache the TCM and the cash are connected
to the main memory use in the umber bus interface.
Like the other two architectures we just look.
We just looked at two.
This is all there is to it.
You don't need to understand how to draw this diagram or how to be able to decode it or anything but
it's just an introduction to fast accessible memory and how a memory works because I'm sure you hear
about cache memory all the time when you're reading your mobile phone specifications or just reading
specifications dealing with better devices.
This is how cache and tightly coupled memory works and I'll see you in the next lesson.