R1CBU alternative firmware for the X6100, patch v0.20.1
=====================================================

WHAT THIS IS
------------
R1CBU's "Patch firmware v0.20.1" ("Patch for SD card", 1.29 MB), published
on r1cbu.ru on 2024-03-17. It updates a card already written with the
v0.20.0 image to v0.20.1. It is the last release by R1CBU himself.

Changes, from the release post:
  Fixed: Callsign and QTH dialogs.
  Added: 6 m band for FT8/FT4.
  Changed: low frequency limit to 500 kHz.

The file is a gzip-compressed tar archive holding a new x6100_gui program
and a settings database:
  ./usr/sbin/x6100_gui   4,180,240 bytes (identifies itself as
                         "X6100 de R1CBU v0.20.1")
  ./mnt/params.db        61,440 bytes

APPLIES TO
----------
A microSD card written with the R1CBU v0.20.0 image (also in this
archive), used in a Xiegu X6100. Not a stand-alone firmware; not for
Xiegu's own firmware and not for the later gdyuldin releases.

BEFORE STARTING
---------------
- A card written with R1CBU v0.20.0 that has been booted at least once.
- A PC that can see the card's DATA partition. On Windows the partition
  may need a drive letter (see IF SOMETHING GOES WRONG).
- The archive includes a params.db (the settings database); whether it
  replaces existing settings on the card was not documented. Note any
  settings worth keeping.

CONTENTS OF THIS ZIP
--------------------
The zip published on fubsypoly.com wraps the vendor file(s)
byte-for-byte, unmodified.

x6100_r1cbu_0.20.1.tgz
    1,347,569 bytes
    SHA-256 479c011d176e24d72b0b89e87bca2c3b898ce103e74a4d447ffb7e1381279bbb
    The patch archive, exactly as downloaded. Do not unpack it.
README.txt
    This file.
SHA256SUMS
    SHA-256 checksums of the files above.

INSTALLATION
------------
From R1CBU's release post ("How install"):
 1. Copy the file x6100_r1cbu_0.20.1.tgz, unchanged, to the DATA
    partition of the R1CBU v0.20.0 SD card.
 2. Put the card in the radio and turn the power on.
The post does not describe what the screen shows while the patch is
applied.

VERIFYING
---------
The program should identify itself as "X6100 de R1CBU v0.20.1". The 6 m
band being available in FT8/FT4 is a visible sign of the patch.

IF SOMETHING GOES WRONG
-----------------------
- The DATA partition is not visible on Windows: R1CBU's post quotes
  K6ANI: File Explorer only shows partitions with a drive letter; in
  Disk Management the card shows three partitions and DATA has no letter.
  Assign one (for example F:) and the partition appears.
- The patch does not take effect: check the file was copied to DATA (not
  to another partition), unchanged and not unpacked, and that the card
  holds v0.20.0.
- To go back to Xiegu's own firmware at any time: switch off and remove
  the card (KE2YK: "Once the SD Card is removed, your transceiver reverts
  back to the factory firmware.").

DOWNGRADING
-----------
To return to v0.20.0, write the v0.20.0 image to the card again (this
erases the card, including the DATA partition).

PROVENANCE
----------
- File: x6100_r1cbu_0.20.1.tgz
- Retrieved from:
  https://www.r1cbu.ru/index.php/home/files?task=download.send&id=20&catid=3&m=0
  (filename as listed on
  https://r1cbu.ru/index.php/home/files/summary/3-x6100/20-patch-firmware-v0-20-1)
- Date retrieved: 2026-09-18
- Official page: https://r1cbu.ru/index.php/home/files/category/3-x6100
  Release post:
  https://www.r1cbu.ru/index.php/home/radio-software/x6100/19-patch-firmware-v0-20-1
- Wayback: https://web.archive.org/web/20240421220408/https://www.r1cbu.ru/index.php/home/files?task=download.send&id=20&catid=3&m=0
- Status: verified (from the author's own site)
- Licence: as for v0.20.0 - source LGPL-2.1 (github.com/strijar/x6100_gui);
  the r1cbu.ru listing shows "License: None".

MORE INFORMATION
----------------
- https://radios.fubsypoly.com/xiegu-x6100/vol-3/
- R1CBU X6100 pages: https://r1cbu.ru/index.php/home/radio-software/x6100
- Source: https://github.com/strijar/x6100_gui
