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UNOFFICIAL Beta-Brite Protocol Information
From http://www.pobox.com/~alsplace/ledsign.html

Compiled by Allen Huffman (alsplace@pobox.com) from various sources.

For official specs, visit http://www.ams-i.com
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Packet Format:

<Min of 5 NUL>		0x00
<SOH>			0x01
<Type 1-byte>		"^" = Beta Brite, "Z" ? or ! =all signs
<Addr 2-bytes>		"00" = broadcast
<STX>			0x02
<Cmd 1-byte>		See below
<data>
*----------------------
<ETX>			0x03
<Checksum 4-bytes>	ASCII hex (on data between STX and ETX, apparently)
*----------------------
<EOT>			0x04

* Checksum is optional.  Instead of <ETX><Checksum><EOT>, you can end
with <EOT> and not use the checksum.

It also appears you can chain multiple messages in one packet by doing
it by repeating the <STX><Cmd><data><EOT> part after the EOT.  (This
does not seem to work with reads.)

John reports that sometimes 9600 baud is too fast.  Adding a delay after
the STX a small delay after the command code seems to help (that is
apparently what the Windows software does).

Cmd Codes:
A	write text file

Follow by the label (1-byte) of which "file" to store the message in. 
"AA" would write to text file "A".  "AZ" would write to text file "Z".

B	read text file

Same as "A", but sign will return a packet
<SOH>"000"<STX>"A"<Message><ETX><checksum><EOT>.

C	?
D	?
------------------------------------------------------------------------
E	write/set memory

Followed by a byte then a hex string.

<0x20>"hhmm"	set time
<0x21>"00" 	speaker off, "11" speaker on
<0x22>		?
<0x23>		?
<0x24>		set file memory followed by...
<0x25>		?
<0x26>		set day of week "1"=Sunday
<0x27>		"S" for AM/PM, "M" for military time
<0x28>		"0" beep, "1" beep beep beep
<0x29><File><start time><stop time>{<file><start>stop><file><start>stop>}
0x2a		?
0x2c		reset?
0x2d		?
0x2e		program the run sequence, follow by...
	<"T" for runtime, "S" based on sequence><"U" unlocked or "L" locked><sequence>
0x2f		dim followed by <on time><off time>
0x30, 0x31	?
0x32<file><start day><stop day>{<file><start day><stop day>}
	"0"=daily, "1"=Sunday ... "8"=weekdays, "8"=weekends, "A"=always, "B"=never

0x33		?
0x34		clear error register in sign

	Memory allocation data - text file

<"A"><"L"ocked or "U"nlocked><size 4-char hex><start time 2-hex><end time 2-hex>
	Time: "FF"=always, "E"=never, "FD"=daytime

	string file

<"B"><"L"ocked or "U"nlocked><size><"0000"> (set string)

<"D"><"L"ocked or "U"nlocked><height><width><"x000" where x is # of colors (bitdepth)>
	size = (((width/5)+1)*height*x)+12
F	read memory

G	write string <label><string text no escape codes allowed> (125 chars max?)
H	read string <label>
	Replies with: <soh><"000"><stx><"G"><label><string><etx><checksum><eot>

I	write dots file

<"I"><label><height 2-byte hex><width 2-byte hex><pause><...roo data...><cr>{<...row data...><cr>}

J	read dots file

<"J"><label>

Message Format:

<ESC><position "0"><mode 1-byte>{special mode 1-byte}<text message>

Modes: a=rotate, b=hold, c=flash, d=?, e=roll up, f=roll down, g=roll
left, h=roll right, i=wipe up, j=wipe down, k=wipe left, l=wipe right,
m=scroll, n=special (add one more byte to specify which), o=auto, p=roll
in, q=roll out, r=wipe in, s=wipe out, t=compressed rotate.

Special Modes (follow "n" above with one of these):  0=twinkle,
1=sparkle, 2=snow, 3=interlock, 4=switch, 5=slide, 6=spray, 7=starburts,
8=welcome, 9=slot machine

Text Control Codes:

^H = add 128 to the next byte that follows (to produce 8-bit characters)
^I = go fast (no delay, "no hold mode")
^J = ?
^K = ?
^L = repeat (4 bytes follow?)
^M = c/r
^N = ?
^O = ?
^P = display another text file here (followed by a file label)
^Q = disable wide
^R = enable wide
^S = time
^T = display dot file here (followed by file label)
^U = speed 1 (slow)
^V = speed 2
^W = speed 3
^X = speed 4

^Y = speed 5 (fast)
^Z = font height (followed by "1" for 5 dots high, "3" for seven dots high)
^[ = then position and mode (?)
^\ = followed by color code
^] = ?
^^ = followed by "0" for prop. font, "1" for fixed width font

Label info: "0" priority -- stop current msg, repeat until it is sent
again with no data OR writing to the RUN table list.  Text files only. 
125 characters length, preallocated.

(pause after label).