I want to expand the memory, but how much can I scale?

The 845 board only supports up to 1G, according to your configuration, the effect is not very obvious, and the difference is not big.

It's an old machine, and it's not cost-effective to add memory, so just add more when you get a new computer.

It is recommended to add to 512

Due to other configurations, no matter how high the memory is, the performance of the device will not be improved much.

DDR400 is used for downclocking.

It is recommended to throw away the 128MB DDR memory, the frequency is too low, and it is the best choice to replace two DDR400 memory. First, it is enough, and secondly, the cost is controlled within 400 yuan. I mean new.

You need the same brand to add memory, so that it will work better, and the motherboard of 845 can be added up to 1g! Otherwise it will be meaningless! Your memory should be DDR, right?

Generally, it is enough to expand to 2G.

Yes, but you can add 512M, or 1G.

Yes, it's best to use the same memory module. How much you can expand depends on how many memory modules you can insert into your motherboard. In general, 4 memory strips can be inserted. This way you can scale up to 4g

The maximum support for DDR200 266 SDRAM DDR400 will be downclocked, only DDR can be used, not DDRIi, because the interface is different.

If your phone is more than 8G memory, it is recommended not to turn it on. Xiaomi's "memory expansion" function is aimed at models with low running memory, slow response, and poor operation, and it makes no sense for high-end and flagship models. The following is a supplement on whether to enable memory expansion, and you can continue reading if you are interested.

1. Test:In the 16APP open memory expansion test,Xiaomi mobile phone has the best performance,The default memory and the background residence after the expansion are 16,And the OPPO mobile phone is the worst,The default memory and the expansion 8G+5G results are exactly the same,Only the OPPO real me GT master exploration edition12G+7G resides in 16APP。

2. Judging from the above tests, turning on memory expansion is similar to not opening the background resident app, so memory expansion is completely meaningless, at most, the surface numbers are better, and some shortcomings of memory expansion cannot be ignored.

3. The performance gap between memory and flash memory is large, so the expanded mobile phone will be stuck, the point is that frequent reading also has an impact on the life of flash memory, and many netizens still recommend turning off the memory expansion function.

4. Therefore, it is recommended to buy a mobile phone with a larger memory directly, without the so-called "memory expansion" function.

The maximum addressing space is 4096 bytes.

Calculation: The language of the computer is binary, so the maximum addressing space = 2 to the 12th power = 4096 bytes.

Addressing space generally refers to the CPU's ability to address memory.

Addressing space generally refers to the CPU's ability to address memory. In layman's terms, it's a question of how much memory can be used.

Data is stored in memory (RAM) is regular, the CPU needs to extract the data when it is operating, it needs to know that the data is stored in **, at this time it needs to be found door-to-door, which is called addressing, but if there are too many addresses beyond the capacity of the CPU, the CPU will not be able to find the data.

The maximum range of addresses that the CPU can find is called the addressing ability, and the addressing ability of the CPU is measured in bytes, such as the 32-bit addressing CPU can address the address of 2 to the 32nd power, which is 4G, which is why the 32-bit CPU can be matched with 4G memory at most, and the CPU will not be found if there are more.

io Ports and Addressing:

In order for the CPU to access the data and status information on the IO interface controller or control card, it needs to first specify their address. This type of address is called an IO port address or port for short. Typically, an IO controller consists of a data port to access data, a command port to output commands, and a status port to access the controller's execution state.

The principle of port unified addressing is to put the port address in the IO controller into the memory addressing address space. For this reason, this type of addressing is also known as memory image addressing. The CPU's operation to access a port is the same as the operation of accessing memory, and it also uses instructions to access memory.

The method of independent port addressing is to treat the addressing space of the IO controller and control card as a separate address space, which is called the IO address space. Each port has an IO address to correspond to, and a dedicated IO directive is used to access the port.

IBM PCs and their compatible machines mainly use independent addressing, which uses a separate IO address space to address and access the registers in the control device. A traditional PC with an ISA bus structure has an I-O address space range of 0x000 0x3ff, with 1024 I-O port addresses available. Table 2-1 describes the range of port addresses that are assigned by default to each controller and control card.

The use of these ports and programming methods will be explained in more detail later when it comes to the hardware involved.

In addition, IBM PCs also use unified addressing in part. For example, the address of the memory displayed on the CGA graphics card, Xiao Yingwan, directly occupies the 0xb800 0xbc00 range of the memory address space. Therefore, if you want a character to be displayed on the screen, you can directly use the memory operation command to write to this memory area.