IBM 4840-563 System Reference Manual page 71

Byte 4: Track 3 start sentinel
The value in this byte is used as the track three start sentinels. It is set to 0x2B by default. The value
assigned to this byte must be an ASCII code between 49 and 63('1'to'?'). This value is substituted in the
return data in place of the sentinel found in the track data.
Byte 5: End sentinel
The value in this byte is used as the track end sentinel. It is set to 0x3F by default. The value assigned to
this byte must be an ASCII code between 49 and 63('1'to'?'). This value is substituted in the return data in
place of the sentinel found in the track data.
Modes
The MSR operates in three modes, functional, command and update. Functional mode is the power on
default mode used by the host application to receive MSR track data. Command mode is used by a
configuration application to change the format and behavior of the MSR when in functional mode. The update
mode is entered from command mode and is used as a means of updating the MSR's firmware. All command
communications between the MSR and the host is through the 2-wire serial interface regardless of the
position of the data selection slide switch. MSR track data is always returned on the 2-wire serial interface on
the JUCC model and on the 2-wire serial or PS/2 interface as selected by the MSR's interface select switch
on the 3-track model.
Functional Mode
The MSR powers up into the functional mode. In this mode the MSR sends track data to the host on either
the 2-wire serial interface or the PS/2 interface. The MSR data interface used is determined by the position of
the data interface slide switch. The JUCC MSR will not have a slide switch and will always return data on the
2-wire serial interface. The format of the track data is determined by the configuration word loaded.
When in this mode the MSR accepts only one command, the enter command mode command. All other
commands should be ignored. Only MSR track data in the configured format is sent to the host. The MSR
start command mode command must be sent before device status can be read. As the MSR transitions from
Functional mode to Command mode a command success string should be sent to the host.
Command Mode
Command mode is entered when a command mode massage is received from the host on the 2-wire serial
interface. In this mode the user can configure the functional mode behavior of the MSR. When configuration
is completed a command is sent that returns the MSR to the functional mode.
When in this mode the MSR accepts commands that change the configuration word, start update mode, or
start functional mode
Update Mode
Update mode is entered when an update command is received from the host while the MSR is in command
mode. In this mode the host updates the MSR's firmware. The new firmware is checked for correctness and
replaces the old firmware. The code update command interface is to comply with the in circuit programming
specification described in Philips Semiconductors application note AN461 2002 Jun 24 for the Philips
89C51Rx2 device.
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