Operating systemsAtari TOS / GEM › TOS 1.0

TOS 1.0

1985

The original 1985 Atari ST operating system, delivering the GEM windowing desktop, initially loaded from disk before moving into ROM.

Machines

Chips

Reference & documentation

External technical references for programming TOS 1.0 and for writing emulators.

ResourceTypeNotes
Atari ST Internals: hardware memory map ↗DatasheetFull ST custom-chip and register memory map
The Atari Compendium (PDF) ↗FormatDocuments GEMDOS 0x601a PRG header and relocation
The Line-A Emulator (tos.hyp) ↗Instruction set$A-line opcode interface below VDI
About the BIOS (tos.hyp) ↗Interrupt listBIOS functions via Trap #13; exception vectors
Atari ST/STe/TT Hardware Register Listing ↗Memory mapComplete I/O register and memory-map listing
GEMDOS Function List (tos.hyp) ↗ProgrammingEvery GEMDOS Trap #1 call by number
Atari ST TOS On Disk 1.00 (Internet Archive) ↗ROMsDisk-booted TOS 1.00 for pre-ROM ST
Atari ST TOS 1.00 (Atarimania) ↗ROMsTOS 1.00 ROM dumps and regional variants
tos.hyp - The Documentation for TOS ↗ReferenceDefinitive maintained TOS/GEM system-call reference
Engineering Hardware Specification of the Atari ST ↗ReferenceAtari's own primary hardware spec document
th-otto/tos1x (TOS 1.00 branch) ↗SourceBuildable original TOS 1.00 assembly source
czietz/ghidraScripts_for_Atari ↗ToolGhidra loaders for PRG and TOS ROM