Operating systems › Commodore GEOS › GEOS 1.0

GEOS 1.0

1986

The 1986 debut of GEOS on the Commodore 64, bundling the geoPaint and geoWrite applications with a Mac-like desktop.

Machines

Commodore 64 (breadbin)

Commodore 64C

Commodore SX-64

Chips

MOS 6510

MOS 6526 CIA

MOS 6581/8580 SID

MOS VIC-II

Reference & documentation

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

ResourceTypeNotes
Inside geoWrite: The VLIR Overlay System ↗FormatVLIR overlay file format internals explained
GEOS File Format Spec (Schepers formats) ↗FormatVLIR, INFO block, and directory-entry byte layouts
GEOS Memory Map (Thornton) ↗Memory mapComplete C64/128 GEOS memory layout with addresses
The Hitchhiker's Guide to GEOS (Berkeley Softworks) ↗ProgrammingOfficial 568-page technical programming notes
cc65 GEOSLib Documentation ↗ProgrammingGEOS API functions and structures for C/asm
GEOS For C64 disk image (Internet Archive) ↗ROMsDownloadable GEOS 64 boot disk image
Zimmers.net GEOS file archive ↗ROMsLarge archive of GEOS disk images and drivers
Hitchhiker's Guide to GEOS (combined Programmer's Reference) ↗Reference860-page merged GEOS API and kernal reference
mist64/geos - GEOS 2.0 KERNAL Source ↗SourceReverse-engineered kernal source; builds byte-identical binaries