Specifications

Chapter 18. TCP/IP

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[ 2 ] Extension Libraries (*.FN3 and *.EX3)

The FTP client treats files with extensions .FN3 and .EX3 as extension libraries.

Extension libraries use a fixed record length of 130 bytes for all records except the last. These

records are separated with line delimiters.

The FTP client automatically pads the last record of a downloaded program file with null codes

(00h) to maintain the fixed-length format. (The number required is 130 less the number of

bytes in the last record.)

Aside: When downloading extension libraries, the BHT uses 128 bytes out of 130 bytes of

record length (the remaining 2 bytes will be used for checking data). To conserve

memory and boost performance, the BHT packs a pair of ASCII bytes into a single

byte by converting each byte into a 4-bit hexadecimal number.

CR LF

Program code

Record

Record length (130 bytes)

CR LF

Record length (130 bytes)

Zeros

Download

CR LF