The 6811 downloaders are general purpose applications for downloading a Motorola hex file (also called an S19 record) into the Handy Board's memory. Each line hex file contains ASCII-encoded binary data indicating what data is to be loaded where into the Handy Board's memory.
For use with Interactive C, the program named ``
pcode_hb.s19'' must be present in the Handy Board. The task of the downloaders, then, is simply to initialize the Handy Board's memory with the contents of this file.
An additional purpose of the downloaders is to program the 6811's ``CONFIG'' register. The CONFIG register determines the nature of the 6811 memory map. For use with Interactive C, the CONFIG register must be set to the value 0x0c, which allows the 6811 to access the Handy Board's 32K static RAM memory in its entirety. Some downloaders automatically program the CONFIG register; others require a special procedure to do so. Please note that programming of the CONFIG register only needs to be done once to factory-fresh 6811's. It is then set in firmware until deliberately reprogrammed to a different value.
Another consideration related to downloaders is the type of 6811 in use. The Handy Board can use both the ``A'' and ``E'' series of 6811. These two chip varieties are quite similar, but not all downloaders support the E series' bootstrap sequence. (The E series chips have more flexibility on their Port A input/output pins and can run at a higher clock speed.)