How is the ASCII number being presented to the MCU? I did something similar awhile back in which the ASCII characters were entered like this:
Code:
Freq
addwf PCL,f
dt "05000000",0
In that case, the ASCII string was included in the code, and I just stepped through the values with tested for zero to end the loop. It was presented here:
https://www.electro-tech-online.com/articles/demo-assembly-code-ad9850-dds-signal-generator.755/
Obviously, it doesn't do the 3-excess coding and converts the ASCII to an actual value (slowly), but the initial part (see: user defined frequency in the link) may give you some help. The instruction sets for the 12F683 and 16F84A are the same. Banking may be a bit different.
John