You can assemble the sources with the assemblers with one of these fine assemblers:

• TASM Telemark assembler, runs on Windows 10 and 11. My favorite.
• A65 assembler, run in DOSBOX or VDOS.
• ASM.80 online assembler
• the assembler from the CC65 suite, powerfull but perhaps overkill for small programs

Other tools that may help you:

• binary file compare (I use freeware WinMerge)
• hex editor (plugin for Notepad++)
• convert between different 8 bit binary files format such as MOS Papertape, Intel Hex, Motorola S-Record, hex dumps. I use my own tool for that: Convert 8bit hex formats

Note that all these assemblers have a different idea about pseudo ops.

• Some require a ‘.’ in front of a pseudo-op like .org
• db, dw instead of .byte, .word
• > < to indicate upper or lower byte, TASM does not know this, use & $FF and >> 8 to mask of upper byte or move upper byte to lower byte.
• 0X or $ to indicate hexadecimal notation

Easy to edit with a Search and Replace usually.

TASM – Notepad++ integration
Install plugin NPPEXEC

• Place TASM in a folder on your disk, e.g. C:\TASM
• Create environment variable TASMTABS with value C:\TASM
• Add c:\TASM to the PATH

Create a NPPEXEC script:

tasm -65  -g3 -s -l  -c -fff "$(FILE_NAME)" "$(NAME_PART).bin"  "$(NAME_PART).lst"  -s "$(NAME_PART).sym"

(-c to combine parts into binary file, -f to fill unused parts in binary with $FF, see TASM manual)

or to produce Intel hex for a programmer:

tasm -65 -x3 -fff -g0 -c -s "$(FILE_NAME)" "$(NAME_PART).ihex"  "$(NAME_PART).lst"  -s "$(NAME_PART).sym"

(-x3 to allow 65C02 instructions)

Now you can edit a source file, save it (CTRL-S), and press CTRL-F6 to execute the NPPEXEC script. The output of TASM is shown in the windows below the source.
If all is well, a Binary, a listing and a Symbol file is produced.

See also:

Elektor Junior ASSM/TED

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KIM-1 Macro Assembler Editor

I bought MAE in 1980 for Use Schroder, Ingenieur bureau Schroder, as a package for the KIM-1. As did some friends in the...

MAE ASSM/TED CW Moser

MAE (Macro Assembler Text Editor) or ASSM/TED is a program sold by Eastern House Software for the KIM-1, Apple, PET, C64...

SYM-1 RAE

SYM-1 Resident Assembler Editor RAE Written by C.W. Moser, other versions known as MAE or ASSM/TED. RAE is an optional ...