 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Apple SOS" – news ·newspapers ·books ·scholar ·JSTOR(April 2010) (Learn how and when to remove this message) |
| Apple SOS | |
|---|---|
 Boot screen | |
| Developer | Apple Computer |
| OS family | SOS |
| Working state | Discontinued |
| Source model | Closed source |
| Initial release | January 1980; 46 years ago (1980-01) |
| Latest release | 1.3 / January 1, 1980; 46 years ago (1980-01-01) |
| Update method | Manual |
| Supported platforms | Apple III |
| Kernel type | Monolithic kernel |
| Default user interface | Full screentext mode |
| License | Apple Software License Agreement |
TheSophisticated Operating System,[1] orSOS (/sɔːs/),[2] is the primaryoperating system of theApple III computer. SOS was developed byApple Computer and released in October 1980.
In 1985,Steve Wozniak, while critical of the Apple III's hardware flaws, called SOS "the finest operating system on anymicrocomputer ever".[3]
SOS is a single-tasking single-user operating system. It makes the resources of the Apple III available in the form of amenu-driven utility program as well as a programmingapplication programming interface (API). A single program is loaded at boot time, called the interpreter. Once loaded, the interpreter can then use the SOS API to make requests of the system. The SOS API is divided into four main areas:
The Apple III System Utilities program shipped with each Apple III computer. It provides the user interface of the operating system itself, for system configuration andfile management. The System Utilities program is menu-driven and performs tasks in three categories:
SOS has two types of devices it communicates with viadevice drivers:character devices andblock devices. Examples of SOS character devices are keyboards andserial ports. Disk drives are typical block devices. Block devices can read or write one or more 512-byte blocks at a time; character devices can read or write single characters at a time.[2]
When powered on, the Apple III runs through system diagnostics, then reads block number zero from the built-indiskette drive into memory and executes it. SOS-formatted diskettes place aloader program in block zero. That loader program searches for, loads, and executes a file named SOS.KERNEL, which is thekernel andAPI of the operating system. The kernel, in turn, searches for and loads a file named SOS.INTERP (the interpreter, or program, to run) and SOS.DRIVER, the set ofdevice drivers to use. Once all files are loaded, control is passed to the SOS.INTERP program.[5]
Apple ProDOS uses the samefile system as SOS. On a disk formatted by ProDOS, the ProDOS loader and SOS loader are written to blocks zero and one, respectively. The ProDOS loader includes code that can execute on an Apple III, and which willchainload the SOS loader from block one, so SOS and ProDOS can co-exist on the same volume. Some software, such asADTPro, makes use of this to store Apple II and Apple III versions of a program on the same disk, which is then bootable on both systems.
The operating system designed for the Apple III computer was called "SOS". This title arose from the Apple III's code name, "Sara", which itself came from the name of the daughter of engineer Wendell Sanders.
This manual describes SOS (pronounced "sauce") the Sophisticated Operating System of the Apple III.
Operating systems byApple | |||||||
|---|---|---|---|---|---|---|---|
| Apple II,III,Lisa | |||||||
| Mac |
| ||||||
| iOS derivatives |
| ||||||
| Others | |||||||
