Improved messages in code and README.md updates.

README.md

@@ -7,37 +7,102 @@ It is written in Python 3 and licenced under GPL v3.
 
 ## Usage
 
+There are really three use cases for the tool at the current time:
+
+  1. Display MicroDrive/Turbo partition table in human-readable format.
+  2. Take a CF card image (or raw CF card device) and extract all the
+     partitions as disk images.
+  3. Take a list of disk images and construct a MicroDrive/Turbo disk image
+     (or write directly to the raw CF card device.)
+
 ```
   mdttool [-haxlCHSG] [-o outputfile] inputfile [inputfile2...]
 
-  -h  Show this help
-  -a  Assemble CF Card image from list of .PO disk images
-  -x  eXplode a CF Card image into constituent partitions
-  -l  Display partition table
-  -C  Set number of cylinders (when assembling new image)
-  -H  Set number of heads (when assembling new image)
-  -S  Set number of sectors (when assembling new image)
-  -G  Set GS ROM version (when assembling new image)
+  -h  --help       Show this help
+  -a  --assemble   Assemble CF Card image from list of .PO disk images
+  -x  --explode    eXplode a CF Card image into constituent partitions
+  -l  --list       Display partition table
+  -C  --cylinders  Set number of cylinders (when assembling new image)
+  -H  --heads      Set number of heads (when assembling new image)
+  -S  --sectors    Set number of sectors (when assembling new image)
+  -G  --gs         Set GS ROM version (when assembling new image)
 ```
 
 ## Display Partition Table
 
+The `-l` flag is used to display the partition table embedded in a
+MicroDrive/Turbo CF card image.
+
 For example:
 ```
-mdttool -l cf-card.img
+$ mdttool -l cf-card.img 
+
+MicroDrive/Turbo Partition Table
+
+  Cylinders:   995
+  Heads:       16
+  Sectors:     63
+  GS ROM Vers: 0
+
+  #    Start      End   Length
+  1      256    65790    65535
+  2    65791   131325    65535
+  3   131326   196860    65535
+  4   196861   696892   500032
+
 ```
 
 ## Explode a CF Card Image into .PO Disk Images
 
+Each partition will be written to a separate file in the current working
+directory.
+
+By default, these images are named `partition1.po`, `partition2.po` etc.
+
 For example:
 ```
-mdttool -x cf-card.img
+$ mdttool -x cf-card.img 
+Writing 33553920 bytes to partition1.po
+Writing 33553920 bytes to partition2.po
+Writing 33553920 bytes to partition3.po
+Writing 256016384 bytes to partition4.po
 ```
 
 ## Assemble a CF Card Image from a list of .PO Disk Images
 
+This command builds a MicroDrive/Turbo partition table from scratch.
+
+The partition table embeds the physical drive parameters - the number of
+cylinders, heads and sectors.  It also encodes the setting for Apple IIgs
+ROM01 and ROM03.
+
+When creating a new CF card image in this way, MDTTool will use the
+hard-coded defaults for cylinders, heads, sectors and GS ROM version.  These
+defaults were copied from typical 512MB CF card.
+
+You can override these with the `-C`, `-H`, `-S` and `-G` command line
+options.  The heads always seems to be set to 16 and the number of sectors
+to 63.  However the number of cylinders depends on the size of the CF card
+in question.
+
 For example:
 ```
-mdttool -a -o new-cf.img part1.po part2.po part3.po
+$ mdttool -a -o new-cf.img partition1.po partition2.po partition3.po partition4.po 
+  Reading partition1.po ...
+  Reading partition2.po ...
+  Reading partition3.po ...
+  Reading partition4.po ...
+New CF card image created in new-cf.img
 ```
 
+Overriding the number of cylinders is done like this:
+```
+$ mdttool -a -C 32000 -o new-cf.img partition1.po partition2.po partition3.po partition4.po 
+  Reading partition1.po ...
+  Reading partition2.po ...
+  Reading partition3.po ...
+  Reading partition4.po ...
+New CF card image created in new-cf.img
+```
+
+

mdttool

@@ -141,7 +141,6 @@ def write_part_tbl(f):
 	    or (parttab['numparts2'] == -1)):
 		print('** Not writing partition table - uninitialized data **')
 		exit()
-	print(parttab)
 	b = [0] * blocksz
 	write16(b, 0x00, magic)
 	write16(b, 0x02, parttab['cyls'])
@@ -221,9 +220,11 @@ def assemble_mdt_image(f, files):
 	write_part_tbl(f)
 	for filename in files:
 		with open(filename, 'rb') as infile:
+			print('  Reading {} ...'.format(filename))
 			d = infile.read()
 			with open(f, 'ab') as outfile:
 				outfile.write(d)
+	print('New CF card image created in {}'.format(f))
 
 def initialize_blank_mdt():
 	pass