CPU: central processing unit http://www.visual6502.org/JSSim/expert-6800.html 1 HZ = 1 clock time 2.34GHZ = 2.34B clock time Register - Data Register - Instructure Register - Address Register - Flag Register: boolean like compare between ALU and control unit ALU (Arithmetic Logic Unit) - Transistor AND, OR, NOT, XOR Control unit

need for a file system hardware file size type authorization read and write time operations common file system: FAT(File Allocation Table) connect by points and write by order ext2(second extended file system) supernode | file sysem descrip | inode bitmap | block bitmap | inode | block use hashmap (inode) record file content inode -> meta Data block -> file content

JVM class loader load code class and other java base classes such as java.io util … static class will be loaded in prepare in link Resolve change symbol reference to actural address parallel to speed up NoClassDeFoundError from the first load part ClassNotFoundException from solve in link runtime data: memory metaspace: class like static, default 64MB max before Java 8 heap: 25% space of memory

Process is a instance of a running program - logical control flow: process execution interleaved - private address space: managed by virtual memory machine - for security Concurrent process their time flow are overlapped A Process with multithreaded Similar Each has its own logical control flow Each can run concurrently Each is context switched different Threads share code and data, Threads are less expensive than processes in some degree

Interruption generates an interrupt interrupt controller Typeahead processor do_IRO() handler() less delay: best: less than 10 ms cache: 1. used before 2. used predictive Http/Https: protocol IPV4: 256^4 IPV6: DNS: nslookup www.google.com traceroute www.google.com port: 443 https 8080⁄80 http Seven Layers: connect with https: (7). Application Layer: https (6). Presentation (5). Session (4). Transport: tcp : find a road from a to b tcp：Three Interaction Protocol