--- a/FCDEV3B-repackaging	Wed Oct 10 17:22:57 2018 +0000
+++ b/FCDEV3B-repackaging	Thu Oct 11 04:58:17 2018 +0000
@@ -114,13 +114,43 @@
   UART and RVTMUX on the IrDA UART.
 
 * Our fw configures the MODEM UART with hardware flow control enabled; if your
-  applications lacks RTS/CTS signals, then Calypso's CTS_MODEM signal needs to
+  application lacks RTS/CTS signals, then Calypso's CTS_MODEM signal needs to
   be pulled down to GND so it is seen as asserted.
 
 * Our fw configures the 4 MCSI/GPIO pins as MCSI rather than GPIO.  If your
   board does not use MCSI because you are tapping VSP instead or not using any
   digital voice interface at all, then you should put pull-down resistors on
   MCSI_RXD, MCSI_CLK and MCSI_FSYNCH, otherwise these signals will float.
+  MCSI_RXD can be directly tied to GND without a resistor as it is always an
+  input to the Calypso, but MCSI_CLK and MCSI_FSYNCH need to be pulled down
+  with resistors: our fw can enable TI's "Bluetooth headset" and "Bluetooth
+  cordless" modes, in which case these signals become outputs.  If the signals
+  are switched to being outputs by software command but are tied to GND on the
+  board, the result will be a shorted output driver which could damage the chip,
+  and it is clearly not acceptable to produce hardware that can be damaged by
+  an AT command, even an obscure and non-standard one.
+
+Cost increment
+==============
+
+If you don't need huge flash and XRAM capacity, don't have a DTR input and are
+not using MCSI, then the incremental cost of being firmware-compatible with
+FCDEV3B compared to Openmoko's approach of leaving all unused signals
+unconnected and using a smaller flash+RAM chip consists of:
+
+* A logic voltage level translating buffer to provide a reset to the flash chip
+  that meets its timing requirements;
+
+* 3 pull-down resistors on GPIO3, MCSI_CLK and MCSI_FSYNCH;
+
+* Direct connections to GND on DSR_MODEM and MCSI_RXD pins.
+
+For parties other than the Mother, it is up to you to decide if being firmware-
+compatible is worth the cost increment or not, but all modem repackagings
+produced by us under the FreeCalypso brand will follow these software and
+firmware configuration management compatibility guidelines, and the same is
+required for anyone else who wishes for their hardware variant to be accepted
+into the FreeCalypso family.
 
 Tapping VSP for the digital voice interface
 ===========================================