Version 1.8 (1-16-26):
	- Updated the FD3712 drive to NOT reset the FIFO pointers when the
	  CLEAR command is issued. This matches the operation of the real
	  hardware and fixes a problem that FDOS exposed.

	- Add a 3/4 second delay before starting selected disk drive code to
	  allow the S-100 bus to stabilize. This fixed a problem someone with
	  a Z80 CPU was having.

Version 1.7 (9-5-21):
      - Added drive type 8, "FDC+3712" which duplicates the capabilities of
	the iCOM/Pertec/Altair FD3712 drive cabinet with its S-100 interface 
	board. This adds IBM 8" SSSD (soft sector) capability to the FDC+.

	See the ReadMe file at the link below for more information about how
	to configure the Altair computer to use this drive type.

	https://deramp.com/downloads/altair/software/icom_floppy/FDC+3712/

Version 1.6 (6-27-21):
      Further improve drive speed tolerance for drive type 4 with the following
      changes:
      - Exit to resync if a rotation exceeds +/-100us from average.

      - Remain in resync loop until a rotation is withing +/-100us of its own
	average. While in resync, allow rotations within +/-2% of nominal to
	be entered into the running average.


Version 1.5 (6-11-21):
      -	Drive Type 4: Support drives that suppress index pulses during sync. 
	The reSync loop is entered as soon as a missing index pulse is detected.
	Normal sector output is resumed once a full revolution at the right
	speed is validated.

      - Drive Type 4: The head status bit in the status register is no longer
	immediately set with the head load command, but delayed by 50ms as with
	normal 8" drive types.

      - Drive Type 4: In the endSector routine, the output compare time for the
	start of the next sector is compared to the output compare clock to
	ensure it is greater (if it isn't, the OC won't trigger for a full timer
	wrap). If not greater, reSync is entered.

Version 1.4 (1-17-21):
     -	Changed the text for the 0us index offset option for the Shugart
	drive type to also state "(for Pertec FD514)."

     -  Changed the 0us index offset option to actually delay 8us instead
	of 0us because a positive, non-zero value is required for proper
	operation.

Version 1.3 (7-10-2020):
     -	Added drive type 5, 1.5Mb Floppy Drive

     -	Drive type 4: Changed the motor off delay to 1 secs to 5 secs.
	Changed the default step rate to 3ms instead of 10.5ms.
	
     -  Drive type 1 and 4: Included trim erase delay like the original
	Altair drive even though an external trim erase signal is not used
	by the Shugart drives.

     -	See the .pdf file, "Release Notes v1.3" for more details.

Version 1.2 (4-27-2020):
     -	Modified all output compare logic to avoid turning output compare on and
	off or using the trigger mode. Based on when external events occur that
	require manipulation of an output compare, it was found these operations
	can cause problems with the OC logic in a manner similar to (and beyond)
	that mentioned in the PIC24FJ errata sheet.

     -	Run all ISRs at the same priority so no ISR nesting occurs. Allows
	elimination of code protect sequences in what were previously low
	priority ISRs.

     -	Updates affecting only the original Altair 8" drive: (These updates
	don't affect operation with any know Altair software but were
	implemented for accuracy and completeness)

	a) The head load timer no longer affects the head step timer.
	 
	b) If an unload head command is received while the disk is writing,
	   the head unload is delayed until trim erase expires. This dupli-
	   cates behavior of the real FDC.
   
	c) Turn off write enable at the next sector pulse instead of 200us 
	   after write data is finished. This timing is more consistent with
	   the orignal FDC when looking at trim erase timing on a scope.

	d) Changed trim erase from 475us to 450us. This results in a 475us 
	   trim erase at the erase head as spec'd by Pertec.

     -	Added support for an 8Mb drive when using the 8" Altair Serial Drive sel-
	ection. The drive looks like an 8" Altair drive with 2048 tracks instead
	of 77. To use this drive, version 1.3 or newer of the FDC+ Serial Server
	must be used. 8Mb disk images are available in the "FDC+ 8Mb CP/M 2.2"
	folder in the Altair CP/M 2.2 folder in the deramp.com downloads area
	(altair/software/8_inch_floppy/CPM/CPM 2.2).

Version 1.1 (3-2-2016):
     -	Added a monitor option to modify the step rate (step time) for non-Altair
	drives.

     -	Added a monitor option to modify the index offset for the Shugart 8" as
	Altair drive type. A properly aligned Pertec drive (i.e., an original Altair
	drive) places data 360us later following a sector pulse than does a properly
	aligned Shugart drive (and most other brands). To allow interchange of
	disks between a Shugart 8" and Altair/Pertec drive, this 360us offset
	is hard-coded in firmware release 1.0. The new menu option allows changing
	this offset for two reasons: 1) To allow use of a direct-connect Pertec
	drive (i.e., no Altair drive cabinet). In this case, the offset should be
	set to zero. 2) To allow adjustment of sector-to-data timing to pull data
	off a disk written on an improperly aligned drive.

     -	Added the Head Current Switch output signal (pin 2 on the IDC-50 cable) for
	the Shugart 8" as Altair drive type. This signal is used with the Altair
	controller, drive, and software, however, the Shugart 80x drives do not 
	require this signal. For this reason, it was not output in firmware release
	1.0. However, other Shugart 80x compatible drives do expect this signal,
	so it has been added.

     - 	A "restore default settings" menu option has been added to the monitor.

     -	Note: Installation of this firmware restores the serial drive baud rate
	(the only parameter that could be modified and saved in version 1.0) to
	its default value of 403.2K baud.

Version 1.0 (3-5-2015)
     -	Initial Release.