Page 245 - The Art of Designing Embedded Systems

232 THE ART OF DESIGNING EMBEDDED SYSTEMS

The goal of including all of this information is to form one repository
which includes pointers to all important parts of the component.

ROM and PAL File Names
All PALs and ROMs will have filenames defined by the conventions
outlined here.
PALs are named: <board>-UcU numben.J<checksum>
ROMs are named: <board>-UcU numben.Vcversion>
Thus, you can tell a ROM from a PAL from the extension, whose
first character is a V for a ROM or a J for a PAL.
Legal <board> names are: (limited to one character)
M - main board
P - option A board
T - option B board
Examples:
M-U 10.JAB main board, U10, checksum=AB
M-U 1 .J 12 main board, U 1, checksum= 12

Engineering Change Orders (ECOs)

ECOs will be issued as required, in a timely fashion to insure all
manufacturing and engineering needs are satisfied.
Every ECO is assigned against a drawing, not against a problem.
You may have to issue several ECOs for one problem, if the change affects
more than one drawing.
The reason for issuing perhaps several ECOs (one per drawing) is
twofold. First, production builds units from drawings. They should not
have to cross reference to find how to handle drawings. Secondly, engi-
neering modifies drawings one at a time. All of the information needed to
fix a drawing must be associated with the drawing in one place.
Each ECO will be attached to the affected drawing with a paperclip.
The ECO stays attached only as long as the drawing remains incorrect.
Thus, if you immediately fix the master (say, change the PAL checksum
on the drawing), then the ECO will be attached to the newly Obsoleted
Master, and filed in the Obsolete file.
If the ECO is not immediately incorporated into, say, a schematic,
then the person issuing the ECO will pencil the change onto the Master
drawing, so the schematic always reflects the way the unit is currently
built.