SDXLXE, multi-game cartridge for Atari XL and XE computers arrives

The SDXLXE is a Multi Cartridge for Atari XL/XE based on UnoCart XL for Atari XL & XE computers. It is basically the little brother of the Ultimate Cart using a slightly cheaper microcontroller. The UnoCart is a multi SD card cartridge for the Atari 8-bit (XL & XE), which supports ROMs,CARs,XEXs and some ATR files.

The SDXLXE system is based on an STM32F4 microcontroller running at 168MHz, fast enough to respond to requests from the Atari 6502 bus running at approximately 2 MHz. Files are loaded from the SD card into the STM32F4's SRAM allowing emulation of Atari cartridges up to 128kb in size.

SD card cartridge for the Atari 8-bit (XL & XE) with support for ROMs, CARs, XEXs, etc.

Like the Ultimate CartThe SDXLXE can emulate a wide range of cartridges and also launches XEX files. However, it is limited to a maximum of 128kb cartridges and XEX files, rather than the Ultimate Cart's 1024k limit. This means that it does not emulate 8mbit Atarimax cartridges, so if you want to make use of these cartridges you will need an Ultimate Cart.

Mode of operation of SDXLXE

The SDXLXE Multi-Cartridge uses a microSD card for storage, so you can reprogram it by simply copying new files to the SD card from your PC or Mac.

When the Atari Xl or XE computer first boots up, the cartridge displays a list of all the files on the SD card. When a ROM or CAR file is selected, the cartridge emulates the selected cartridge type. The SDXLXE supports standard 8k and 16k ROMS, XEGS cartridges up to 128k in size, AtariMax 1mbit, Bounty Bob, OSS cartridges and many more.

XEX files (Atari executables) are also supported using an XEX loader built into the cartridge.

SDXLXE menu

The menu allows you to browse through the files on a microSD card and select a title to use. Use the cursor up, cursor down and [Return] keys to select items. Press [B] to return to the main directory. Press [ESC] to browse for a file. Press [X] to disable the cartridge and boot normally (e.g. from an SIO device) - this allows you to leave the cartridge plugged in.

Led indicator

The red LED indicates that the cartridge is working properly and is powered. When the menu is active, the green light will indicate access to the SD card. After selecting a menu title, the green light indicates that the cartridge is active (No).

Reset button

Press the reset button (next to the SD card slot) to reset the cartridge. This will usually cause the Atari to lock up, and the Atari reset button can be pressed to return to the cartridge menu (No).

CAR files and ROM files

Both CAR and ROM files contain the data of a cartridge. However, CAR files have an additional 16-byte header containing the cartridge type that makes it clearly identifiable to the UnoCart. In contrast, the cartridge type of a ROM is ambiguous - for example, an 8k ROM file could be an 8k standard cartridge, or an 8k OSS cartridge.

ROM files 

Normal ROM files are supported, but as these files are dumps from raw cartridges, the UnoCart will decide which type of cartridges they come from based on file size alone. The following table shows the types of ROM files that can be used on the cartridge:  

• ROM File Size Cartridge Type
• 8k Standard Atari 8k
• 16k Standard Atari 16k
• 32k Atari XEGS 32k
• 64k Atari XEGS 64k
• 128k Atari XEGS 128k
• Supported Cartridge Types (CAR files)
• Description CAR Type(s)
• Standard Atari 8k 1
• Standard Atari 16k 2
• Atari XEGS 32-128k 12-14
• AtariMax 1mbit (128k) 41
• Switchable XEGS 32-128k 33-35
• Megacart 16-128k 26-29
• Bounty Bob 18
• Williams 32k, 64k 8, 22
• OSS 8k 44
• OSS 16k (034M) 3
• OSS 16k (043M) 45
• OSS 16k (type B) 15
• SIC!Cart (128k only) 54
• SDX 64k 11
• Diamond 64k 10
• Express 64k 9
• SDX 128k 43
• Blizzard 16k 40

The SDXLXE cartridge can also emulate a disk drive on an Atari with at least 64k. This is done by installing a Soft OS on the Atari which then redirects D1: to the ATR file selected in the menu. The access for D2: upwards is still directed to the SIO port as usual. Many games will not work, due to the Soft OS technique used. However, it is possible to boot into a DOS 2.5 ATR file, do some programming in BASIC and save the program back to the ATR file. ATR files up to 16Meg in size are supported.

3D printed enclosure for SDXLXE

The casing is a design in 3D printing which is mainly intended to keep the PCB safe and allow the cartridge to be inserted perfectly into an Atari XL or XE computer.

The firmware used in SDXLXE is open source.

Credits

• Design, hardware and firmware by Robin Edwards (electrotrains at atariage)
• XEX loader and operating system modifications by Jonathan Halliday (flashjazzcat at atariage)
• Altirra LLE OS used with the permission of Avery Lee (phaeron atariage)
• German translation of the user manual by Florian D (FlorianD at atariage)
• Production by Marlin Bates (MacRorie at atariage)

Do you want an SDXLXE cartridge?

Contact us and we will get back to you as soon as possible.

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