View source for Sprite port-mirror Attribute 1 (with INC) Register

{{NextRegister
|Number=$76
|Readable=No
|Writable=Yes
|ShortDesc=Same as {{NextRegNo|$36}} (write second byte of sprite-attributes), plus increments {{NextRegNo|$34}}
}}
Eight low bits of Y position. MSB of Y-pos is in "byte 5".

After write into sprite-attribute "byte 2" ({{PortNo|$xx57}}), the {{NextRegNo|$34}} is incremented (with all consequences stemming from such action). If the sprite 127 was modified, the result of the increment is officially "undefined behaviour", and code should explicitly set valid 0..127 sprite index before next sprite-attribute manipulation.