Repair manual

2-49
THEORY OF OPERATION
Table 2-11. Camera Type Codes
1-Byte Code ASCII String
128 (80 hex) Pack Film
129 (81 hex) 35mm
130 (82 hex) Auto Film
131 (83 hex) 4 x 5
When a camera back is attached to the Digital Palette, camera
back data (CBDATA 1-4) indicating the camera back type is
applied via connector J11 to the data select lines of a dual 4-line to
1-line data selector/multiplexer.
Before the exposure process is initiated, the host computer queries
the Digital Palette for the attached camera back type by sending
an Inquire Camera Back command via the applicable parallel
interface to the computer Imager buffer memory. Upon receipt of
this command, the microprocessor network removes and executes
the Inquire Camera Back command from the buffer memory. It
flags the camera back select data instructions from the EPROM.
The EPROM applies the camera back select data instructions to the
input of the microprocessor network via the Address/Data
communications bus. The microprocessor network decodes the
camera back select data instructions from the EPROM and then
applies them via the Address/Data communications bus to the
input of the address latch network.
Specified address latch select signals from the microprocessor
network, output the camera back select data via the Latch/Address
communications bus to the data select lines of dual 4-line to 1-line
data selector/multiplexer.
The dual 4-line to 1-line data selector/multiplexer outputs a 1-byte
code followed by an ASCII string describing the camera currently
attached to the Computer Imager via the Address/Data
communications bus to the applicable parallel interface.
Upon command, the applicable parallel interface sends the data
describing the camera concurrently attached to the Digital Palette
to the host computer. A message is displayed on the host
computer indicating the type of camera back that is attached to the
Digital Palette