Web site: members.chello.nl/taf.offenga/atari_dev.htm (not active)
Origin: USA
Category: Game
Desktop environment: GUI
Architecture: Atari
Based on: Independent
Wikipedia:
Media: Install
The last version | Released: 1984 (?)
XL OS – on operating system contained in the ROM of Atari XL and XE series computers.
It is a development version of Atari OS rev. B, improved and expanded. The system occupies 16k in the address area from $C000 to $FFFF.
XL OS consists of the following components:
– Interrupt handlers
– CIO
– SIO
– Mathematics package
– Binary relocator (ACX)
– New device handlers
– Test program (SELF TEST)
Unlike previous versions, there is no distinction between PAL and NTSC versions – the system automatically recognizes the hardware version and adjusts its internal settings accordingly.
As a curiosity, the system includes a so-called “attention mode” – a simple screen saver that activates when the user doesn’t touch the keyboard for approximately 11 minutes (exactly 32,768 VBL “frames,” or 10 minutes and 57.2 seconds in PAL). After this time, the brightness of the displayed image is reduced by half, and the background, text, and frame colors begin to change approximately every 5 seconds. Pressing any key restores the computer to normal.
The XL OS resides in a 16k ROM, generally located in the $C000-$FFFF area. However, this memory is not fully linearly mapped to the 6502’s address space. The table below illustrates the differences between the physical location of the system ROM contents and their logical location in the address space.
