OK, three votes for an error message. Glad there was a consensus! I'll make that change to the assembler code and get an update posted in a few days.

thank you all for your input!
Daryl

Little late to the voting booth but I agree with throwing an error if the accumulator is set as 8bit mode ...

I went looking through the lists of '816 assemblers, but have been unimpressed. Maybe I didn't look into them well enough. What '816 assembler do you use? What do you like about it? What do you not like about it?
I use a homemade assembler with the concept from Table Assembler (external CPU ...

I'm too late but my attempt comes in at 66 bytes on the C256 Foenix's 65816 using my own assembler.
cpu '65816'
org $60
const width=72
const treepattern=array(1,3,5,9,3,7,11,15,19,5,11,17,23,3,3)
PUTC = $001018
main:
phk
plb
sep #$30
ldy #sizeof(treepattern)-1
-
lda #' '
ldx treedata,y,b ...

One of the features I use and value most in the macroassembler AS is named local labels. Any label that starts with a period is considered local to the scope between the two nearest global labels. I find things like JMP .loop and BEQ .exit to be a lot more readable and reliable than using the ...

Take a look at addresses $D018 and $DD00 which from my memory sets the address of where the tile set/character memory/font is located in a 16KB bank and which 16KB bank is seleected. If you time the change of values at those addresses with a raster interrupt you'll be able to display more than one ...

I was trying to find an alias for "dword" and from my Pascal experience the word "cardinal" comes to mind. The meaning of "dword" is very straight forward, double word or 4-bytes. Cardinal is a mathematical term but why was it chosen to represent a dword or 32-bit number?

.text "CRT TITLE"
.fill $0040 - *, $00 ; pad title with $00
That's interesting because I thought I was being innovative with my own assembler. This is my variation on the same directive/code.
.byte ("CRT TITLE") pad $40; for space padded ..pad $40($20) That pads after the text, use -$40 to pad ...

One part of the linking process that has me concerned is in regards to code/data being placed in zero or direct page. If the assembler generates object code using absolute addressing, by default, and then the linker comes along and places the code/data into zero or direct page, ideally the opcode ...

Most 65xx assemblers tend to be of the traditional multi pass variety writing a binary file in the last pass and then there are the handfull of linker types. Everyone has their own preference and my past experiences has been with the multi pass type but more recently I've been looking at the linker ...