- Very early C compilers and language (cm.bell-labs.co)
Several years ago, Paul Vixie and Keith Bostic found a DECtape drive, attached it to a VAX, and offered to read old DECtapes. Even at the time, this was an antiquarian pursuit, and it presented an opportunity to mine beneath the raised floor of the computer room and unearth some of the DECtapes we’d stored since the early 1970s. Gradually, I’ve been curating some of this, and here offer some of the artifacts. Unfortunately existing tapes lack interesting things like earliest Unix OS source, but some indicative fossils have been prepared for exhibition.
- Understanding the x86’s Decimal Adjust after Addition (DAA) instruction (righto.com)
I’ve been looking at the DAA machine instruction on x86 processors, a special instruction for binary-coded decimal arithmetic. Intel’s manuals document each instruction in detail, but the DAA description doesn’t make much sense. I ran an extensive assembly-language test of DAA on a real machine to determine exactly how the instruction behaves. In this blog post, I explain how the instruction works, in case anyone wants a better understanding.
- The Underhanded C Contest (underhanded-c.org)
The Underhanded C Contest is an annual contest to write innocent-looking C code implementing malicious behavior. In this contest you must write C code that is as readable, clear, innocent and straightforward as possible, and yet it must fail to perform at its apparent function. To be more specific, it should perform some specific underhanded task that will not be detected by examining the source code.
- C (programming language) (Wikipedia)
C (pronounced /ˈsiː/ – like the letter c) is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C’s features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems code (especially in kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems.