Intermec EasyCoder 501 XP Service Manual page 96

15.2 Circuits, cont.
CAUTION!
The Electronic Key Circuit (P34) contains
an integrated lithium battery.
Replace only with original
Electronic Key Circuits from Intermec.
Dispose of used Electronic Key Circuits
according to local regulations for lithium
batteries.
Intermec EasyCoder 501 XP – Service Manual Ed. 4
DRAM Memory (P23 and P24)
The DRAM memory (Dynamic Random Access Memory) is the
printer's temporary memory (device "tmp:"). It will lose its con-
tent when the power is switched off or at a power failure. Thus,
it should only be used for data that can easily be recreated or that
is only relevant for one power-on cycle. It is much faster than the
fl ash memory. Therefore, at startup the kernel is copied from the
Flash memory to the DRAM, where the various Intermec Finger-
print instructions are executed.
One DRAM SIMM (standard size 4MB) must always be installed
in socket P23 (DRAM0).
The DRAM is also used for the font cache and various buffers. The
remainder is used for the two print image buffers where the bitmap
patterns are stored prior to printing. One buffer is used for the
label that is being printed, while the other receives the bitmap for
next label as the Intermec Fingerprint instructions are processed.
By switching between the buffers, batch printing without stopping
between labels can be achieved.
The size of the buffers depends on two factors:
• Number of physical dots on the printhead (regardless of "Media;
Width" and "Media; X-start" setup)
• Present "Media; Length" setup value in dots
Calculate the buffer size according to this formula:
(No. of dots / 8 + 4) × (Media length in dots) = Buffer size in bytes
(Buffer size in bytes) / 1024 = Buffer size in kbytes
Buffer size in kbytes × 2 = Memory requirement in kbytes
Example:
The number of dots on the printhead is 1280
The Media; Length is set to 1800 dots (≈ 150 mm/5.9 inches)
[[(1280 / 8) + 4) × (1800)] / 1024] × 2 ≈ 577K total
If a longer print length or more storage space is required, the
memory can be expanded with a second DRAM SIMM with
a technical limit of 32MB in socket DRAM1-2, which gives a
max. total DRAM size of 36MB. However, regardless of memory
size there is an absolute print length limit of 32,767 dots (2,730
mm/107.5 inches). Refer to the spare parts price list for up-to-date
information on approved DRAM SIMMs.
Electronic Key Circuit (P34)
The Dallas touch memory key in P34 contains a real-time clock
circuit (and a system key that is no longer used). The circuit has
a built-in battery backup with a life of at least 10 years. When the
printer is on, the circuit is power supplied via the CPU board and
will not consume any power from the battery.
The circuit also contains 4Kbits (500 bytes) of battery backed-up
memory for the devices "lock:" and "storage:".
Chapter 15 CPU Board
95