HP 250C - Manual (Page 56)

5Ć14 Functional Overview C4699Ć90000
ROM
The plotter firmware code is contained on either an inĆbuilt masked ROM (soldered to the
main PCA) or a flash ROM SIMM (installed in the innerĆmost socket at the back of the
plotter). If both are present, the plotter recognizes the code on the ROM SIMM instead of
that on the inĆbuilt ROM. The powerĆon LED sequence tells you whether the plotter is using
code from inĆbuilt ROM or from a ROM SIMM. (Details ' page 8Ć3.) To find out the
firmwareĆcode revision level that the plotter is using, print a user setup sheet or a service
configuration plot.
RAM
The plotters have a standard four megabytes of onĆboard RAM. They also have one RAMĆ
expansion socket, which can hold an optional 4Ć, 8Ć, 16Ć or 32Ć megabyte DRAM SIMM. The
socket is the outerĆmost one at the back of the plotter.
EEROM
EEROM is used as nonvolatile storage for calibration and configuration data. Useful
information from the EEROM is printed on the service configuration plot ' page 8Ć49
(DesignJet 230/250C) or page 8Ć50 (DesignJet 330/350C). The EEROM is soldered to the
Main PCA in both new and rebuilt electronic modules.
If you clear the EEROM or replace the electronics module, perform all calibrations. Also note
that the factory spittoon value on the cleared or new EEROM is 0%. Keep in mind that the
value printed on the service configuration plot may greatly underestimate the amount of ink in
the spittoon. Future PCĆbased plotter diagnostics will enable you to download information from
the old EEROM and upload it to the new EEROM. (Clearing the EEROM ' page 8Ć54/8Ć55.)
Input/Output Interfaces
Like the DesignJet 220, the plotters have both a parallel (BiĆTronics) and a serial (RSĆ232ĆC)
interface. Unlike the DesignJet 650C, they have no modular input/output (MIO). You can
connect the plotters to a network by means of an HP JetDirect EX or HP JetDirect EX Plus3
external print server. (See also ' chapter 1, w Network Connections, and chapter 10,
w Accessories.)
BiĆTronics
In addition to the operating modes of the DesignJet 220, the BiĆTronics interfaces of the
DesignJet 230 and 250C and DesignJet 330 and 350C feature the extendedĆcapabilityĆport
(ECP) forward and reverse operating modes, providing for faster communication.
RSĆ232ĆC
The supported baudrates are 1200, 2400, 4800, 9600, 19200 and 38400, with eight bits and no
parity, or seven bits with either odd or even parity. Mark parity is not supported. Both
XON/XOFF and DTRhandshaking are supported. ENQ/ACK handshake is not supported.