Microcom 322M - Manual (Page 71)

Chapter 8 Downloadable Fonts
322M Operator’s Manual
67
The encoded result would like this:
“00 00 01 02 03 04 00 05 FF 00 FD FF 04 00 00 FF 00”
Result interpretation:
00 - the first byte is 00
00 - count of 0 (the previous 00 byte is not repeated or repeated zero times)
01 - a 01 byte
02 - a 02 byte
03 - a 03 byte
04 - a 04 byte
00 - another 00 byte in the file
05 -
the 00 byte is repeated 5 times for a total of 6 “00” bytes (00+05=6 “00” bytes)
FF - a FF byte
00 - count of o (the previous FF byte is not repeated or repeated zero times)
FD - a FD byte
FF - another FF byte
04 - the FF byte is repeated
4 times for a total of 5 “FF” bytes (FF+04 = 5 “FF” bytes)
00 - another 00 byte
00 - repeat count = 0
FF - another FF byte
00 - repeat count = 0
This compression scheme is slightly inefficient for single 00 HEX and FF HEX occurrences
but most image bitmaps include large areas of either blank space (00 HEX) or black space
(FF HEX).
If a string of more than 255 00 HEX or FF HEX occurs, the byte-plus-count sequence may
be repeated as often as necessary to incorporate all occurrences of the byte. For example,
a string of 1132 “FF” HEX bytes in sequence may be encoded as:
“FF FF FF FF FF FF FF FF FF 6B”
The first four pairs of FF HEX each encode 256 bytes of FF HEX (one for the first FF byte
and 255 copies) totaling 1024 bytes of FF HEX. The next FF HEX byte adds another byte
and the 6B HEX adds 107 additional bytes for a total of 1132 FF HEX bytes.
(4 X 256)+1+107 = 1132
8.2.2 Uncompressed Image (^D104)
This command allows graphic and/or font images (fonts must be less than 64KB
uncompressed) to be transmitted in ASCII-HEX, thereby allowing all data to pass over 7 or
8-bit data connections. This command is useable on data connections that support either 7
or 8-bit data.
The following is the format of the ^D104 command when used for a graphic image file:
^A<Slot Number>^D104<CR>
<Rotation> <Count> <Image Data>
Where: