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iohead

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iohead
·3 năm trước·discuss
Well, V7 UNIX is rather arbitrary as a reference point for comparison. There was what we now call as V1 UNIX, which would be circa 1971/72, so that's certainly 50+ years old. Compared to what's shown in the article, some of the data structure fields and constants would be different and/or missing in the still earlier versions. DIRSIZ would be 8, for example.
iohead
·3 năm trước·discuss
The fancy names and the layering makes it a little tricky to understand. The core of the imaging model is called Quartz. It provides support for rendering 2D shapes and text. Its graphics rendering functionality is exported through the Quartz 2D API, which is implemented in Core Graphics. Quartz is also used for window management: the Quartz Compositor, a lightweight window server, is implemented partly in the WindowServer application and partly in the Core Graphics framework. Quartz 2D uses PDF as the native format for its drawing model. In other words, it stores rendered content internally as PDF, which facilitates features such as automagic PDF screenshots, export/import of PDF data natively, and rasterizing PDF data. Quartz 2D also does device-independent and resolution-independent rendering of bitmap images, vector graphics, and anti-aliased text. NEXTSTEP's window server was based on Display PostScript, so was Sun's NeWS (~1986).
iohead
·3 năm trước·discuss
As part of a project code-named "Jaguar", Apple did consider using a Motorola 88K variant as their future RISC-based hardware, but it was short-lived and they moved on to the POWER Architecture. In 1991, Apple, IBM, and Motorola formed the "AIM" alliance with the goal of creating a Common Hardware Reference Platform (CHRP). This led to the PowerPC architecture, which included most of the POWER instructions along with some additions and deletions.
iohead
·3 năm trước·discuss
No, not quite. The macOS/iOS kernel is extremely Frankenstein-y (not meant in a derogatory way), with the majority of codebase being extremely Apple-specific, and bits and pieces originally taken from Mach and BSD. In particular, there is no microkernel, and there never was. Mach itself was never used as a true microkernel in a commercial setting, with the first such implementation--Mach 3--showing significant real-life performance problems. As such, there is no "BSD on top of a Mach microkernel". It is and has always been a fully monolithic kernel with some subsystems originally derived from Mach (Open Group's Mk 7.3), some from BSD (FreeBSD 5), and the rest developed in-house over the years. Even the layerings aren't always clean, with "on top of" often morphing into "alongside" or "intertwined with".