Memory Allocation - Keysight Technologies X-Series Programming Manual

Creating and Downloading User–Data Files
Signal Generator Memory

Memory Allocation

Volatile Memory
The signal generator allocates volatile memory in blocks of 1024 bytes. For
example, a user–data file with 60 bytes uses 1024 bytes of memory. For a file
that is too large to fit into 1024 bytes, the signal generator allocates additional
memory in multiples of 1024 bytes. For example, the signal generator allocates
3072 bytes of memory for a file with 2500 bytes.
As shown in the examples, files can cause the signal generator to allocate
more memory than what is actually used, which decreases the amount of
available memory.
User–data blocks consist of 1024 bytes of memory. Each user–data file has a
file header that uses 512 bytes for the Keysight X-Series signal generator, or
256 bytes for the ESG/PSG in the first data block for each user–data file.
Non–Volatile Memory
Non–volatile files are stored on the non–volatile internal signal generator
memory (i.e. internal storage) or to the USB media, if available. The Keysight
X-Series signal generator non–volatile internal memory is allocated according
to a Microsoft compatible file allocation table (FAT) file system. The signal
generator allocates non–volatile memory in clusters according to the drive size
(see
and if the file is less than or equal to 4k bytes, the file uses only one 4 KB
cluster of memory. For files larger than 4 KB, and with a drive size of 15 MB,
the signal generator allocates additional memory in multiples of 4KB clusters.
For example, a file that has 21,538 bytes consumes 6 memory clusters (24,000
bytes).
On the Keysight X-Series signal generators, the non–volatile memory is also
referred to as internal storage and USB media. The Internal and USB media
files /USERS/NONVOLATILE Directory contains file names with full extensions
(i.e. .marker, .header, etc.).
For more information on default cluster sizes for FAT file structures, refer to
Table 6-3
Table 6-3
Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide
3 x 1024 bytes = 3072 bytes of memory
Table 6-3). For example, referring to
and to http://support.microsoft.com/.
Drive Size and Non-volatile Memory Clusters
Drive Size (logical volume)
0 MB – 15 MB
16 MB – 127 MB
128 MB – 255 MB
256 MB – 511 MB
Table 6-3, if the drive size is 15 MB
Cluster Size (Bytes)
(Minimum Allocation Size)
4K
2K
4K
8K
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