XMIT command success

i’ve been on vacation and busy with some other things, so i didn’t have a chance to work on the 8-bit project for a couple of weeks.  but the last two weekends i’ve been working on the XMIT command, and finally finished it up.  as usual, there were a couple of stupid little bugs in the assembler that i didn’t catch.  one was properly loading up the X register with the number of full pages to transmit, and the other was not having copied the data location information into the alternate location for use as a counter.

coding XMIT actually wasn’t all that difficult – i just started by copying the code for RECV and switching the sense from receiving to transmitting.  i also needed to update my PC-side utility to allow it to receive as well as transmit data.

the form of the command is

XMIT a$xxxx,l$yyyy

where ‘a$’ and ‘l$’ represent the starting address and length of the data to be sent, respectively.  both arguments are required, and the order must be as shown – because i’m taking a shortcut and ignoring the letters and assuming that the arguments are in this order.  i also skip the $s and assume that the value is in hex – decimal simply isn’t allowed.  i justify this because a) it works and b) i do intend, if i ever manage to complete this project and get it running on my own hardware design, to at that point go back and flesh out the firmware to provide a better user experience.

the format of the transmitted data is identical to that for the RECV command.

with XMIT and RECV now both working, i think the next step is to go back to the hardware side and integrate the serial hardware onto my breadboard, bypassing the SSC.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s