The MiSTeryNano is a port of the MiSTery Atari STE FPGA core to the Tang Nano 20k FPGA board.

The MiSTeryNano is a work in progress. Current features are:

• Atari ST/STE
  • Complete Atari ST/E chipset
  • ST or STE configurable
  • Cycle exact 8 MHz 68000 CPU
  • 4MB RAM, optional 8MB STRAM
  • color and monochrome video via HDMI
  • YM2149 and STE DMA sound via HDMI
  • Blitter
• Supports most TOS
  • Tested with german TOS 1.04, german TOS 2.06 and US TOS 1.00
• Full IKBD implementation
  • Mouse via IO pins of Tang Nano
  • Joystick via IO pins of Tang Nano
• Floppy disk image stored on regular FAT formatted SD card
  • Tested with several 4, 16 an d 32 GB cards
  • Up to 32 .ST disk images selectable via on-screen-display

• Support for keyboards
• Support for floppy drive B
• Support for hard disk images
• Floppy disk write support

Currently the FPGA on the Tang Nano 20k is around 87% full and this setup is considered to be mostly complete with respect to the FPGA itself. Further development will focus on the BL616 microcontroller of the Tang Nano 20k which will allow to implement the missing features.

MiSTeryNano has been developed and tested under Linux. Thus the following explanations expect a Linux system to be used. The installation consists of three steps:

Use openFPGAloader to install the MiSTeryNano core named atarist.fs on your Tang Nano 20k:

$ openFPGALoader -f impl/pnr/atarist.fs 
write to flash
Jtag frequency : requested 6.00MHz   -> real 6.00MHz  
Parse file Parse ../atarist/impl/pnr/atarist.fs: 
Done
DONE
Jtag frequency : requested 2.50MHz   -> real 2.00MHz  
Jtag frequency : requested 10.00MHz  -> real 6.00MHz  
erase SRAM Done
Detected: Winbond W25Q64 128 sectors size: 64Mb
Detected: Winbond W25Q64 128 sectors size: 64Mb
RDSR : 00
WIP  : 0
WEL  : 0
BP   : 0
TB   : 0
SRWD : 0
00000000 00000000 00000000 00
Erasing: [==================================================] 100.00%
Done
Writing: [==================================================] 100.00%
Done

Most TOS images should be supported by now. This has been tested with US TOS 1.00 (60 Hz NTSC video) and german TOS 1.04 and TOS 2.06 (both 50 Hz PAL video).

This needs to be flashed into the flash ROM of the Tang Nano 20k at 1MB offset:

$ openFPGALoader --external-flash -o 1048576 tos162de.img
write to flash
Jtag frequency : requested 6.00MHz   -> real 6.00MHz  
Parse file DONE
Jtag frequency : requested 2.50MHz   -> real 2.00MHz  
Jtag frequency : requested 10.00MHz  -> real 6.00MHz  
erase SRAM Done
Detected: Winbond W25Q64 128 sectors size: 64Mb
Detected: Winbond W25Q64 128 sectors size: 64Mb
RDSR : 00
WIP  : 0
WEL  : 0
BP   : 0
TB   : 0
SRWD : 0
00100000 00000000 00000000 00
Erasing: [==================================================] 100.00%
Done
Writing: [==================================================] 100.00%
Done

Now the MiSTeryNano should already boot into the TOS desktop in ST mode.

For STE mode a STE capable TOS needs to be flashed to a different flash location:

$ openFPGALoader --external-flash -o 1310720 tos206de.img

This TOS image is always use when STE mode is selected (see the configuration section below)

Since releae 0.9.0 MiSTeryNano supports reading floppy disk images from a FAT formatted SD card. This has only been tested with 16 and 32 GB cards. Especially smaller cards may not work if the FAT file system uses less then 8 sectors per cluster.

At least a file named DISK_A.ST needs to be placed in the root directory of the SD card. This file is by default used as a disk image for floppy drive A. Further .ST disk images can be placed in the root directory of the SD card. Up to 32 disk images can be handled by the core at the moment.

The SD card is to be inserted into the slot on the bottom side of the Tang Nano 20k inconveniently placed right below the USB connector. The MiSTeryNano will automatically load a file named DISK_A.ST and use it as the image for floppy disk drive A.

You can use the buttons on the left and right of the USB-C connector on the Tang Nano to change disk images. Button S1 will open the on screen display. Short presses on S1 will step through the installed images. Pressing S2 will insert the current image into floppy drive A. A long press on S1 will close the on screen display without changing the installed disk images.

Button S2 will also act as a reset button for the Atari ST when the on screen display is not open.

The MiSTeryNano currently implements some basic mouse control via five digital direction inputs on the Tang Nano 20k which need to be switched to GND.

Alternally a Blackberry Trackball can be used on the same pins. In this case the TRACKB config switch needs to be closed.