View source for Subor Mouse

A mouse came with Subor's SB2000 famiclone system.

Example games:
* ''Educational Computer 2000''

=== Input ($4016 write) ===

 7  bit  0
 ---- ----
 xxxx xxxS
         |
         +- Strobe

=== Output ($4017 read) ===

 7  bit  0
 ---- ----
 xxxx xxxD
         |
         +- Serial data

The mouse returns either 1-byte or 3-byte responses based on the size of the x/y axis movement since the last read.
If the movement value for both the X and Y axis is between -1 and 1 (inclusively), the mouse returns a 1-byte response.  Otherwise, a 3-byte response is sent. In this case, the strobe bit must be toggled 3 times in a row to read the entire response (e.g read $4017 8 times, toggle strobe bit, read 8 more times, etc.)

==== 1-byte response format ====
 
 LRXXYY00
 ||||||||
 ||||||++- Always 0
 ||||++--- Y movement (0: no movement, 1 or 2 = went down 1 unit, 3 = went up 1 unit)
 ||++----- X movement (0: no movement, 1 or 2 = went right 1 unit, 3 = went left 1 unit)
 |+------- Right mouse button (1: pressed)
 +-------- Left mouse button (1: pressed)

The mouse button order is opposite that of the [[Super NES Mouse]].

==== 3-byte response format ====
 
'''Byte 1'''
 LRSXTY01
 ||||||||
 ||||||++- Always 01
 |||||+--- Y movement (Bit 4)
 ||||+---- Y movement direction (1: up, 0: down)
 |||+----- X movement (Bit 4)
 ||+------ X movement direction (1: left, 0: right)
 |+------- Right mouse button (1: pressed)
 +-------- Left mouse button (1: pressed)

'''Byte 2'''
 --XXXX10
   ||||||
   ||||++- Always 10
   ++++--- X movement (Bits 0-3)

'''Byte 3'''
 --YYYY11
   ||||||
   ||||++- Always 11
   ++++--- Y movement (Bits 0-3)

== References ==
* [http://problemkaputt.de/everynes.htm#controllerstrackballandmouse Nocash's EveryNES documentation]

[[Category:Controllers]]
[[Category:Pointing devices]]