Sega SG-1000
This page was last modified 12:33, 21 October 2020 by Mars2000you. Based on work by Gdx and Bodhi1969.
SG-1000 logo



SG-1000 is a game console with hardware close to MSX1s, the main difference is the sound chip. It was released in July 1983 in Japan.

The joystick that comes with this console can not be disconnected from the console. The SJ-200 joystick which was sold separately was intended for Player 2 only.

EOM versions had been sold into some other countries. Sega has made several consoles based on the SG-1000 and even a computer (SC-3000) up to the Master system using a cartridge adapter.

Power supply is external.

Price at launch: ¥15,000

An optional keyboard SK-1100 allows to convert the console in something close to the SC-3000 computer.

Brand Sega
Type SG-1000
Year 1983
Region Japan
Original price ¥15,000
Media SG-1000 cartridges
Video Texas Instruments TMS9918A
Audio Texas Instruments SN76489AN
Keyboard layout
Extras SJ-200 joystick


Sega SG-1000 first version + joystick
Sega SG-1000 box first version
Sega SG-1000 box back first version
Sega SG-1000 second version + joystick
Sega SG-1000 expansion slot
Sega SG-1000 box second version
Sega SG-1000 bottom
Sega SG-1000 v1 PCB
Sega SG-1000 v2 PCB


CPU is a NEC Z80 (μPD780C-1) or a Sharp (LH0080A) with 1kB of RAM (C000h~C3FFh). SG-1000 doesn't have BIOS.

The SG-1000 RAM is expandable with following cartridges:

  • BASIC Level II B: It contains 1kB RAM + 32kB ROM (BASIC interpreter)
  • BASIC Level III A: It contains 16kB RAM + 32kB ROM (BASIC interpreter)
  • BASIC Level III B: It contains 32kB RAM + 32kB ROM (BASIC interpreter)


  • The Sega BASIC cartridges require the keyboard SK-1100 to be usable.
  • There is also BASIC Level II A but it contains no RAM.

Controller port uses same connector as MSXs but pins 7-9 have different order. Do not insert a SG-1000 controller into an MSX without JoyMega.


  • RF-output
  • SG-1000 cartridge slot
  • 1 expansion slot (for Keyboard SK-1100, etc)
  • 1 joystick port for joystick 2 (DE-9 type), joystick 1 can't be removed
  • Power supply input (DC +9V, 7.7W)

Run SG-1000 software on MSX

SG-1000 software can't run on MSX without some changes. Several loaders for DOS are available.

  • SG1000 loader by gdx (require external SN76489)
  • SG2MSX loader by Tiny-Yarou (support external SN76489 from the Musical Memory Mapper)
  • SofaSMS by Louthrax (support external SN76489)

The differences between the SG-1000 and MSXs are:

  • Memory map
  • Used I/O ports
  • PSG is a SN76489 instead of AY-3-8910 (noise generator is on a separate voice)
  • Controllers

Fixes and upgrades