While the feature set is minimal, the low overhead means you could theoretically press truly ancient PCs into service. There’s certainly an appeal to being able to write your code on a modern OS and effortlessly deploy it on a retrocomputer, from somewhat modernized versions of early ...
RISC means reduced instruction set: a small set of simple (atomic) instructions that may be combined into more complex operations. RISC指精简指令集:由简单(原子的)指令构成的小指令集合,由它们可以组合成更复杂的操作。 2.3 x86内存管理 1. What is the range of addressable memory in protected mode?
CISC means complex instruction set: a large collection of instructions, some of which perform sophisticated operations that might be typical of high-level language. CISC指复杂指令集:大指令集合,其中的一些执行可能是高级语言特有的复杂操作。 16. Describe the RISC design approach. 描述RISC设计方法。 RISC...
The presence of wide SIMD registers means that existing x86 processors can load or store up to 128 bits of memory data in a single instruction and also perform bitwise operations (although not integer arithmetic[15]) on full 128-bits quantities in parallel. Intel's Sandy Bridge processors added...
(2) Bit fields occupy as many bits as you assign them, up to 4 bytes, and their length need not be a multiple of 8 bits (1 byte) Table 6 Scalar Alignment Data Type char short int enum pointer float double long double long double (64-bit operating system) long [int] 32-bit on...
which means that the processors have a 32-bit bus for memory and data and has 32-bit registers. However, the main difference is that x86 is limited to only 4GB of addressable memory space and can only parallel transmit 32-bits on a single go, making it slower than the 64-bit systems....
The Operating System's kernel, drivers, networking- and storage-subsystems are typically considered trusted in most contemporary mainstream operating systems such as Windows, Mac OSX and Linux; with Qubes OS being a notable exception [@qubes_arch]. This means the architects of these systems assumed...
The most significant bit is rotated to the carry flag, the carry flag is rotated to the least significant bit position, all other bits are shifted to the left. The result includes the original value of the carry flag. The first operand value indicates how many times the rotate takes ...
This means that indirection through the ebp and esp registers that default to the ss register won't also default to ds (because ds!=ss). Conversely, indirection through the other registers which default to ds won't default to ss. The threads share everything else including data and code ...
Rather than having long double be an 80-bit type except when passed as a variadic method argument, in which case it would be coerced to 64 bits, many compilers decided to make long double be synonymous with double and not offer any means of storing the results of intermediate computations....