FOXBORO FBM237 RH914XS 到货PLC自动化备件

FOXBORO FBM237 RH914XS 到货PLC自动化备件

FBM237 RH914XS 映射表内存以与主内存相同

一个早期的虚拟内存系统IBM M44/44X需要访问保存在中的映射表磁心存储器在每次编程访问主存储器之前。

由于没有缓存，并且映射表内存以与主内存相同的速度运行，这有效地将内存访问的速度减半。

两台早期的机器使用了页表在用于映射的主存中IBM System/360 Model 67和GE 645，两者都有一个小的关联内存作为访问内存页表的缓存。

在第一台机器之前，这两台机器都有主存缓存IBM System/360 85型所以计算机系统中使用的第一个硬件缓存不是数据或指令缓存，而是TLB。

FBM237 RH914XS maps the table memory to the same as the main memory

An early virtual memory system, the IBM M44/44X, required access to the mapped table stored in the core memory before each programmatic access to the main memory.

Since there is no cache, and the mapped table memory runs at the same speed as the main memory, this effectively halves the speed of memory access.

Two early machines used page tables in main memory for mapping the IBM System/360 Model 67 and GE 645, both of which had a small associated memory as a cache for accessing the in-memory page tables.

Before the first machine, both machines had main memory caches IBM System/360 85 so the first hardware cache used in a computer system was not a data or instruction cache, but a TLB.