Friday, April 23, 2010

Amiga 1.0

Let's take a tour through some of the AmigaOS versions, courtesy of the WinUAE emulator.  WinUAE is great, because it allows us to emulate various hardware configurations without having to invest the time in configuration of real hardware.  Various versions of the AmigaOS are available online in collection form, if your persistent enough to find them.

Amiga 1000, Kickstart 1.0, WB 1.0

The Amiga 1000 was the original Amiga, and I will be booting this virtual machine using the original OS and a standard factory configuration. Since the machine did not have a built in ROM, the A1000 required a Kickstart disk upon hard-reset. The first thing that greets us on startup is a screen requesting this disk and some notes from the speaker.
After insertion of the Kickstart 1.0 disk (OK, really an ADF file containing an image of the disk, but let's pretend we have actual hardware here), we get a similar screen to the first requesting the Workbench Disk.  Unless we hard-reset (i.e. turn off the power) we shouldn't need the Kickstart disk again, since the machine reads its contents into a write-protected 256KB area of memory (known as Writable Control Store (WCS).)  After the initial boot, the WCS acts as if it were a ROM to the machine.
Workbench 1.0 wasn't the prettiest environment among its contemporaries, with its blue-white-black-orange color scheme.  This color scheme was actually chosen for a reason - it bled less on color televisions.  Monitors were still expensive, often costing a significant percentage of the machine cost, and were not all that common in "home" computers (think C64)  Commodore was betting that Amiga users would be using home televisions as their display devices.

The 1.0 Workbench uses a file-folder metaphor to presenting programs, similar to the Macintosh, GEOS, and Windows.  Workbench specific information about a file or folder is stored in a separate file with a ".info" extension.  Workbench doesn't actually display the files, but uses the .info files to control the action.  Here you see the default screen after double-clicking on the Workbench disk icon.  The left border of the window shows a fuel-gauge indicating that the disk is about 3/4ths full, and the top border shows the name of the open window.  Standard controls on a window are a close button, a minimize button to shrunk the window to an icon on the desktop, and a button that brings the window to the foreground if it is occluded behind other windows.  At the bottom right is a resize tool to control the size of the windows.  Visible on the Workbench disk are a few "drawers" (directories), a clock tool, a preferences tool, and a trashcan tool.  Operation of these should be immediately obvious to anyone today which is a good indication of how strong this metaphor is.  Notice I said "visible" - remember the workbench only displays .info files - also part of AmigaDOS is a powerful command-line environment, which we will explore shortly.
Here I have started the clock utility and opened the System drawer.  Since the Amiga is fully multi-tasking, the clock utility runs as its own process, independent of anything else running on the system.  This was truly groundbreaking for a home computer in 1985.  Inside the System drawer are  a few utilities like a disk copier and formatter, and the CLI (Command Line Interface) entry-point.  Although the CLI is the default operating mode of the Amiga (it starts there, executing a script called "S:Startup-Sequence", the Workbench takes over from it and in order to get back you need to start a new one.
Here I have started the CLI and executed the "list" command, which gives file information on the current directory.  I have also left the Clock running in the background to demonstrate how it continues to run undeterred.  Yes this doesn't seem like much in 2010, but in 1985 the ability to run more than one program at a time was the province of workstations and bigger machines.  Note also the aforementioned .info files for the drawers.  Also notice that there are other files on the disk, not visible in the Workbench.  These comprise of various system-level directories, such as libs and c.  The AmigaOS did a good job of hiding its complexity from the user in the Workbench, but fully exposed it through the CLI when the power was needed.

Our last stop on this brief tour is in the Preferences tool, since I think it is a good indication of the maturity of the system, or lack thereof.  For Workbench 1.0 the Preferences tool was simple and compact, but didn't allow much customization for the user.  The user could set the mouse speed and double-click speed, the key repeat, adjust the basic four colors of the Workbench, set the time and baud rates, adjust the mouse pointer and printer, and... that's about it.  The more adventurous were going to have to learn to play with the CLI.

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