TOS Emulator with 256KB Decoder
SidecarTridge TOS Emulator and 256KB decoder
The SidecarTridge 256KB Decoder is an add-on board for Atari ST and Mega ST computers. Used together with the SidecarTridge TOS Emulator, it enables support for 256KB TOS ROMs on systems originally limited to 192KB ROMs. This allows users to run a wider range of TOS versions, including TOS 2.06 and EmuTOS 256KB.
Overview
The 256KB Decoder is soldered onto the Motorola 68000 CPU and works in combination with a custom carrier board. It provides address decoding and chip enable (CE) signal generation for the $E00000–$E3FFFF memory range required by 256KB ROMs, which are standard on Atari STe and Mega STe models but not natively supported by earlier ST and Mega ST computers.
Features
- Supports emulation of 192KB and 256KB TOS ROMs. - Provides address decoding for the $E00000 ROM range. - Generates the necessary chip enable (CE) signal for 256KB ROM access. - The decoder board is installed on top of the Motorola 68000 CPU. For Mega ST computers, a version with a Blitter patch is available to facilitate installation where a Blitter chip occupies the same area.
The Blitter patch is optional and can be used or omitted as needed.
Usage
Once installed, the decoder allows the SidecarTridge TOS Emulator to access and switch between TOS images of various sizes. This is useful for testing, development, or using TOS versions not originally available for the Atari ST or Mega ST.