Receiving From The Printer; Handling Errors - Nintendo GAME BOY Programming Manual

3.2 Receiving from the Printer

The printer returns 2 bytes of status data.
Byte 1: Device number
1 0 0
The value of the MSB is always 1. The lower-order 7 bits represent the device number.
The Pocket Printer is device number 1.
Byte 2: Status
LowBat ER2
LowBat:
ER2:
ER1:
ER0:
Untran:
Full:
Busy:
Sum:
Status information is sent in reply to each 2 bytes of dummy data sent by the Game Boy.
* The status returned by the printer is FF FF when the printer is not connected to the Game Boy or
not powered on.

3.3 Handling Errors

Either an error number listed below or the error number plus a description of the error would be sent
to the display screen in response to an error flag in byte 2. (This information is also presented in the
user's manual of the Pocket Printer. That information must be used together with the information
given here.)
Status: Byte 2
low Bat = 1
FF FF
ER1 = 1
ER2 = 1
* Error No. 02 is represented using both status bytes.
ER0 = 1 likely indicates program failure.
0 0 0
ER1 ER0 Untran
1 = Low-battery error bit
0 = Battery OK
1 = Other error
1 = Paper jam (abnormal motor operation)
1 = Packet error
1 = Unprocessed data present
0 = No unprocessed data present
1 = Image data full
0 = Image data not full
1 = Printer busy
0 = Printer ready
1 = Checksum error
0 = Data OK
Error No.
01
02
03
04
239
0 1
Full Busy
Chapter 9: Pocket Printer
Sum