Hallelujah! Maybe a Bug found in B.A.L. code?

Alex Bell

Hey Forum Folk: I've been pulling my (last, few) hairs out over this one: code fragments in listing 10.1 of Al William's Beginning Assembly Language, Ver 2.0 pp 147, seem to be missing a "#" sign in the reset_entry loop that, when replaced, seems to make my "Packet Radio" code work. If anyone else has used this UART code, maybe you could look at it and see if is a typo or whether I am off my rocker... it is: mov tx_divide, txdivisor, but I think the line SHOULD read: mov tx_divide, #txdivisor.
I was noticing that when breakpoints are set, the ISR was not having the txdivisor properly loaded at the start of the loop, and then when the loop was decremented it was rolling from "00" back to "FF" and so, there was a HUGE space at the begining of the UART output. Then, subsequent loops loaded the correct divisor until the 8 bits were done....at the start of the next byte, a huge space again...
In the ISR portion of the code it is shown with a # sign, but NOT in the reset_entry section. I am attaching Mr. William's code from the downloads section of this site. Thanks for having a look. Alex

mojorizing

Hi Alex,

I hate when that happens....

Looks like you found it. Dropping the "#" is a surprisingly common, in my case at least. Instead of an actual number value, you end up referring to a register some where deep down in your code.

Good deal, Kevin

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There are 10 kinds of people in the world.... those that know binary, and those that don't.