First command       5a 81 42 31 4e 7f 7f 23 05 09 0d

Second command      5a 31 42 91 40 7f 7f 26 0d

if you send a 26 command back, you get a 24 command out:

26 response (24 >)  5a f1 43 11 41 7f 7f 24 0d

If you send a 24 back, and some conditions are met, you get a 25

24 response (25>)   5a 21 4e e1 40 10 7f 25 0d

25 issues resp      5a 21 4e e1 40 10 7f 25 0d

21 command:         5a F1 40 D1 41 7f 7f 26 0d

22 response:           5a f1 41 91 41 7f 7f 22 0d

22 cmd:

b9b6 <> 0
buffer,5 = byte before cmd (7f)
b9b6 <>0




All commands are 5a ch ch ch ch A B Cmd

A is either b996 or b995


ba24 is start of transmit
ba26 is start of output routine.


ba81 is start of something.

bab1 is start of second command
output at (22)=b98a
x=*b996 = 7f
jsr ba9d
y=7
*(22),y = a = 26
y--
*(22),y=*b994 = 7f
y--
a=x (7f)
*(22),y=a=7f
rts to baa0
a=08
*b9ab=a=08   ; how many bytes to chksum, starting at 5
jsr bc65



0d37 is rs-232 routine.

b877 is called from b851 and looks like input check.

tk=117 causes first and second messages to be sent.  (i.e. no second pass via e367...)


Known variables: 

9af0      holds initial 10 byte buffer

b988      temp counter (ref b877, b8af)

b98a      holds buffer (8 bytes?)

b992      holds 0d (bac3) 

b993      =? ca84 (ref bb46,b90e) 
          b994=b993, inc, =? 80, =10 (ref bc54) 
          02fc= (ref a04a)   
          =? b9ab (ref b975)
          +50-b9ab =? 20 (ref b97a)

b994      stored in b998 (ref bae1) 
          ($22),06= (ref ba4d) 
          =?ca84 (ref bb19) 
          =b993 (ref bc57)

b995      is offset 5 of msg (ref bc12) 
          stored in b996 (ref bcb4) 
          ++ to 80 then =10 (ref bcba) 
          stored in 02fe (ref a059) 
          .X= (ref ba89) (part of X,b994,a buffer setup)

b996      =B995 (ref: a05c,bcb4) 
          holds 7f, transmitted at offset 5 of msg (ref babb) 
          stored in 02ff (ref a05c) 

b997      =0 (ref 9a4f,b92a,ba1b) 
          ored with b9b6 (ref bd86) 
          =?0 (ref bdbd)
          =7 (ref b9e3) (location in buffer of command)

b998      =0 (ref ba18, ba7b,9a47) 
          =*b994 (ref bae4)
          =? 0 else =0 (ref ba73)
          =? 0 else =b994 (ref badc)


b999      =0 (ref 9a47) 
          =?8 (ref BAD8) 
          b999,y=.A (ref bb51)
          b999=?b9ab (ref bb9d)

b99a      b99a,y = 0 (ref bb56) 
          b999,y = b99a,y (ref bbad)

b99b

b99c

b99d

b99e

b99f

b9a9      =1 (ref 9a5f) 
          =?8 (ref b9f3,bad8,bbce)
          =b9ab (ref b93d)
          b9ad-b9ab >? -1 else +8, b9a9= (ref ba64)
          b9ac=b9a9 (ref b866,b940, b9ed)

b9aa      =9 (ref ba3f)
          -- (ref baee)

b9ab      =0a (ref 9a31) is number of bytes to checksum (also could just be buffer len)
          =? ($22),5 (ref b954)
          b993=? b9ab (ref b975)
          b993+50-b9ab =? 20 (ref b97a)
          =.Y (ref b9bd)
          =.A (ref bb97)
          b9ad-b9ab >? -1 else +8, b9a9= (ref ba64)
          =0 (ref ba61)
          =8 (ref ba94)
          =.X (ref bbd9)
          +=0a (ref bbf5)

b9ac      b9ac=b9a9 (ref b866,b940, b9ed)
          X= (ref bbe2) (bbe2 uses it as an index into b9af:b9b0)
          =ff (ref b866)
          -- (ref b95a)

b9ad      b9ae= (ref 9a47,bb0b) must be incoming buffer pointer (number /2 * 80 + b400)
          b9ad =? b9ae (ref b9c0)
          b9ad-b9ab >? -1 else +8, b9a9= (ref ba64)

b9ae      =b9ad (ref 9a57) must be outgoing buffer pointer (number /2 * 80 + b400)
          b9ad =? b9ae (ref b9c0,bb86)
          ++&7 (ref b9e6)
          --&7 (ref bb86)

b9af      22 = bbaf,x (ref bbe5)

b9b0      23 = bbb0,x (ref bbe5)

b9b5      ++ to $ie (ref 90a0)
          =? 0 else retransmit (ref baca,bb34)
          =0 (ref bb2f)

b9b6      =0 (ref 9a52) 
          ora b997 (ref bd86) 
          =?0 (ref ba5c)
          =?0 else =0 (baf9)
          =?0 else b9ab=ca85+1 (ref bb6e)
          =1 (ref bbc7)


b9b7

b9b8      =0a (ref bbc2)

b9b9      =0 (ref 9a52)
          =? 0 (ref b9c8)  (checks this, if <>0, sets back to zero and does some processing
          if this is non-zero, we have started a command.)
          = 'Z'   
          = ff (ref b9b9,bb90)

b9ba      =8 (ref b84c)

b9bb

bcfe      holds byte to be checksummed
bcff:bd00 hold 16 bit checksum
bdb4      holds 3 (ref bdac)

ca6c      (51820)
          holds 1 letter of command (taflocpa)

ca80      buffer`

cedd      (52957)
          get tk value.  117 is first one.

0335-0337 (821-823)
          holds command mnemonic (tlk,inf,fun,lrn,lib,c64,stp,acc)

Buffers:

b400,b480,b500,b580,b600,b680,b700,b780  are buffers (ref bcc3,ba03)


Sprites:

0800 has Q sprite
0840 has u sprite
0880 has a sprite
08c0 has n sprite
0900 has t sprite
0940 has u sprite
0980 has m sprite
>C:09c0 ************************
>C:09c3 *******.****************
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>C:09cf *********.*.*.*******.**
>C:09d2 ***.*****.*.*.*****..***
>C:09d5 ****..**.*...*.**..*****
>C:09d8 ******..*.....*..*******
>C:09db ********.......*********
>C:09de ***........*......******
>C:09e1 ********.......*********
>C:09e4 ******..*.....*..*******
>C:09e7 *****.**.*...*.**.******
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(C:$09ff) ms 0a00
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(C:$0a3f) ms 0a40
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>C:0a49 ****.*********.***.*****
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>C:0a5e ***........*..........**
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(C:$0a7f) ms 0a80
>C:0a80 ************************
>C:0a83 **.*****************.***
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>C:0a8c *****.*****.*****.******
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>C:0a9e *****......*........****
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>C:0aaa ***.*****.*.*.*.***.****
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(C:$0abf) ms 0ac0
>C:0ac0 ************************
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>C:0ac9 ****.******.******.*****
>C:0acc *****.*****.*****.******
>C:0acf ******.**.*.****.*******
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>C:0ad5 ****..**.*...*.**.******
>C:0ad8 ******..*.....*..*******
>C:0adb ********.......*********
>C:0ade *******....*......******
>C:0ae1 ********.......*********
>C:0ae4 ******..*.....*..*******
>C:0ae7 ****..**.*...*.**..*****
>C:0aea **..***.*.*.*.*****..***
>C:0aed *.****.**.*.*.*******.**
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(C:$0aff) ms 0b00
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>C:0b0c ********.**.************
>C:0b0f *.****.**.*.*.**.*******
>C:0b12 **..***.*.*.*.*.***.****
>C:0b15 ****..**.*...*.**..*****
>C:0b18 ******..*.....*..*******
>C:0b1b ********.......*********
>C:0b1e *****......*....********
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>C:0b24 ******..*.....*..*******
>C:0b27 ****..**.*...*.**..*****
>C:0b2a ***.***.***.*.*.***.****
>C:0b2d ******.****.*.**.*******
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>C:0b3c ************************