Frequently Asked Questions
This section compiles a list of frequently asked questions (FAQs) aimed at addressing common inquiries, clarifications, and concerns. Developers are encouraged to consult this section for quick references and insights.
General Questions
What is the maximum number of ROMs that the SidecarTridge TOS emulator can support?
It depends on the board revision you have:
- Board revisions 1 and 2: The number of ROMs that the device can support depends on the carrier board, not the SidecarTridge ROM emulator itself. The emulator is compatible at the signal level with any ROM, EPROM, or EEPROM with a bus width of 17 or 18 bits (256KBytes of address space), 8 or 16 bits of data bus, and CE and/or OE signals.
- Board revision 3: the board stores up to 64 TOS images in its 16 MB, and serves images of up to 512 KB. The Atari ST, STE, Mega ST and Mega STE motherboards use 192 KB or 256 KB TOS images, so those are the sizes you will use.
Why is the SidecarTridge TOS emulator not compatible with certain Atari ST motherboards?
Incompatibility usually arises from the lack of a carrier board that supports the specific number of ROMs required by the motherboard and the layout of the ROM sockets. Eventually, the SidecarTridge TOS emulator aims to be compatible with all Atari ST motherboards with the appropriate carrier board, subject to time and resource constraints.
Can I use the SidecarTridge TOS emulator with an Atari ST motherboard that is not listed as supported?
Potentially yes, but it is best to inquire first. For unique or unknown motherboards, contact us to discuss compatibility and the possibility of developing a carrier board for it.
Can I use the SidecarTridge TOS Emulator with modified computers or CPU accelerators?
The TOS Emulator is designed, tested and supported on Atari ST, STE, MegaST and MegaSTE computers in their original stock configuration. Modified machines, including memory expansions, CPU accelerators, custom logic replacements, bodge wires and aftermarket ROM adapters, are out of scope and not covered by warranty. The only exception is the standard Atari Blitter patch on the Mega ST, which remains supported.
If your machine is modified, please contact us before ordering. Some users report that certain CPU accelerator setups work in combination with the TOS Emulator, but such configurations are unsupported and used entirely at your own risk.
Why is the SidecarTridge TOS emulator limited to 256KB ROMs maximum?
Board revisions 1 and 2 use the RP2040 microcontroller, which can serve up to 256 KB of ROM. Board revision 3 serves up to 512 KB thanks to the RP2350 microcontroller, but the Atari ST, STE, Mega ST and Mega STE motherboards only use 192 KB or 256 KB TOS images.
Why is the SidecarTridge TOS limited to 16MBytes of Flash storage?
The microcontroller on the board (the RP2040 on board revisions 1 and 2, the RP2350 on board revision 3) addresses up to 16 MB of flash memory. The firmware, the ROMEMUL drive and the board’s settings share it.
Will the SidecarTridge TOS emulator support larger Flash storage in the future?
This is a possibility, depending on future hardware developments.
Why do I need a RESCUE button?
The RESCUE button recovers the SidecarTridge ROM board in case of a failed firmware update or a broken image, allowing you to restore the device to a known good image. This is specially useful for developers and users who want to experiment with custom firmware.
Why is the RESCUE button not on the SidecarTridge ROM board?
Due to space constraints and the potential for users to access the RESCUE button through a cable or case hole, it is not included directly on the SidecarTridge ROM board.
Why does the SidecarTridge TOS emulator use a FAT12 filesystem?
The FAT12 filesystem is used to ensure compatibility with all operating systems, including Windows, macOS, and Linux. It is a simple and efficient filesystem that is easy to implement and use.
Why is the name of the TOS images limited to 63 characters?
The board keeps the list of TOS images in a small, fixed space, with 64 bytes for each name; one of them marks the end of the name, which leaves 63 characters. Longer names are cut when the list is built. The SWITCHER’s rename prompt says “max 64 characters”, but 63 can be typed.
Hardware Questions
There is no power LED on the SidecarTridge TOS emulator. How do I know if it is powered on?
Board revisions 1 and 2 of the SidecarTridge TOS emulator do not have a power LED. However, the device is powered on when the carrier board is connected to the Atari ST motherboard and the Atari ST is powered on, or when the SidecarTridge TOS emulator is connected to a USB power source.
When the SidecarTridge TOS emulator is powered on and connected to a USB power source, you must press the RESET button during a few seconds to start the device. Then, it will appear as a USB drive on your computer with the name ROMEMUL.
Board revision 3 of the SidecarTridge TOS emulator has a red LED that indicates when the device is powered on.
Can I use a 256KB ROM image in a ST/STF/STFM motherboard?
You can’t use a 256KB ROM image in a ST/STF/STFM motherboard because these motherboards only support 192KB ROMs.
Also, keep in mind that the TOS for ST/STF/STFM motherboards starts at address 0xFC0000 and ends at 0xFEFFFF. The STE/MegaSTE TOS starts at 0xE00000 to 0xE3FFFF.
If you want to use a 256KB ROM image in a ST/STF/STFM motherboard checkout the 256KB Decoder version of the SidecarTridge TOS emulator.
Software Questions
How do I update the firmware of the SidecarTridge TOS emulator?
Follow Firmware installation. To move a board revision 3 from firmware v3.x to firmware v4.0.0, follow Upgrading to v4.0.0.
Can I install firmware v4.0.0 on my board revision 1 or 2?
No. Firmware v4.0.0 is for board revision 3, the one with a red power LED. Board revisions 1 and 2 keep firmware v2.1.0, their last version, with SWITCHER 2.1.0.
Do I need the new SWITCHER and rescue switcher with firmware v4.0.0?
Yes. Firmware v4.0.0 works only with SWITCHER 4.0.0 and the rescue switcher 4.0.0; the older ones stop with a “not compatible” message. Upgrading to v4.0.0 explains how to replace them.
I want to update the firmware of the SidecarTridge TOS emulator but I don’t want to lose my TOS images. What should I do?
There are two kinds of firmware file:
- the update file (
sidecartridge-tos-rp2350a-v4.0.0.uf2) replaces the firmware only. It keeps your TOS images and settings. - the full files (
...-emutos-192k-full-...and...-emutos-256k-full-...) install everything new, with EmuTOS. They erase your TOS images.
Use the update file. Firmware installation explains how to install it.