Compatibility:
From a code standpoint the MC6800, MC6802 and MC6808 mpu’s are interchangeable.
MC6802 is a MC6800 with 128 bytes of RAM and an on-board oscillator.
MC6808 is a MC6800 with an on-board oscillator but no RAM.
In fact, MC6802’s with defective RAM were often sold as MC6808 chips.
Similarly, the MC6801 will execute MC6800/MC6802/MC6808 code but it has 10 additional
instructions so it is not backwards compatible, unless care was taken not to use any of the
10 additional instructions.
As for the MC6809, the MC6809 will not run machine language compiled for the
MC6800/MC6802/MC6808 because the MC6809 uses different opcodes. However, the
MC6809 assembly language instructions are a subset of the MC6800 instructions.
Therefore, if you re-assemble the MC6800 assembly language code using a MC6809
assembler... the resulting code will run on the MC6809. There is no need to change the
MC6800 assembly language code.
I've recently been told that the 6800/6802/6808 use a subset of the 6801/03 opcodes ( with a few of the flags behaving differently on some instructions) and the 6801/03 use a subset of the 68hc11 opcodes.
Naming Convention Anomaly:
68HC11 refers to the MC6811
68HC05 refers to the MC6805
68HC08 does NOT refer to the MC6808!
From a code standpoint the MC6800, MC6802 and MC6808 mpu’s are interchangeable.
MC6802 is a MC6800 with 128 bytes of RAM and an on-board oscillator.
MC6808 is a MC6800 with an on-board oscillator but no RAM.
In fact, MC6802’s with defective RAM were often sold as MC6808 chips.
Similarly, the MC6801 will execute MC6800/MC6802/MC6808 code but it has 10 additional
instructions so it is not backwards compatible, unless care was taken not to use any of the
10 additional instructions.
As for the MC6809, the MC6809 will not run machine language compiled for the
MC6800/MC6802/MC6808 because the MC6809 uses different opcodes. However, the
MC6809 assembly language instructions are a subset of the MC6800 instructions.
Therefore, if you re-assemble the MC6800 assembly language code using a MC6809
assembler... the resulting code will run on the MC6809. There is no need to change the
MC6800 assembly language code.
I've recently been told that the 6800/6802/6808 use a subset of the 6801/03 opcodes ( with a few of the flags behaving differently on some instructions) and the 6801/03 use a subset of the 68hc11 opcodes.
Naming Convention Anomaly:
68HC11 refers to the MC6811
68HC05 refers to the MC6805
68HC08 does NOT refer to the MC6808!
Tools:
Let's face it... half the challenge of programming old microprocessors is finding tools that can run on more modern computers... here are a few gems that I've come across. If you know of others please drop me an email using the "contact me" form.
HIPPY IDE - This is a great (although incomplete) open source IDE with a limited but sufficient debugger for the Motorola 68xx family. Sadly it appears that there is no ongoing development for this tool.
You can find it here: HIPPY
Notes:
To compile using Hippy:
Open the .asm file in HIPPY.
Select "Compile and Load" (not "Compile")
Select "export to S file"
THRSim11 IDE - (Update: It appears that this tool is now FREE! Be sure to check it out... you'll want to make a small donation... it's that good!) Not free but very flexible and most importantly... still available. There used to be plenty of development tools for the popular Motorola 68xx family. Unfortunately, if the company still exists, they rarely can find any of their old programs... I know because I have contacted several. It really is a shame that these fine tools were not saved. Anyway... THRSim11 is still available and is a very complete IDE. It even provides you the ability to define the memory locations of your particular system. Furthermore, I believe you can debug your C/C+ code using this tool... but I never have... straight assembly for me. I purchased a copy and use it as my main simulator for 6809 assembly code. Technically the program is for the 68HC11 but the 6808 instruction set is a subset of the 6811 (i.e., the 68HC11 is upward compatible with the MC6808)... so it works just fine.
You can find it HERE: THRSim11
MACRO ASSEMBLER AS - recommended by a visitor to this site.
You can find it HERE: Macro Assembler AS
Let's face it... half the challenge of programming old microprocessors is finding tools that can run on more modern computers... here are a few gems that I've come across. If you know of others please drop me an email using the "contact me" form.
HIPPY IDE - This is a great (although incomplete) open source IDE with a limited but sufficient debugger for the Motorola 68xx family. Sadly it appears that there is no ongoing development for this tool.
You can find it here: HIPPY
Notes:
To compile using Hippy:
Open the .asm file in HIPPY.
Select "Compile and Load" (not "Compile")
Select "export to S file"
THRSim11 IDE - (Update: It appears that this tool is now FREE! Be sure to check it out... you'll want to make a small donation... it's that good!) Not free but very flexible and most importantly... still available. There used to be plenty of development tools for the popular Motorola 68xx family. Unfortunately, if the company still exists, they rarely can find any of their old programs... I know because I have contacted several. It really is a shame that these fine tools were not saved. Anyway... THRSim11 is still available and is a very complete IDE. It even provides you the ability to define the memory locations of your particular system. Furthermore, I believe you can debug your C/C+ code using this tool... but I never have... straight assembly for me. I purchased a copy and use it as my main simulator for 6809 assembly code. Technically the program is for the 68HC11 but the 6808 instruction set is a subset of the 6811 (i.e., the 68HC11 is upward compatible with the MC6808)... so it works just fine.
You can find it HERE: THRSim11
MACRO ASSEMBLER AS - recommended by a visitor to this site.
You can find it HERE: Macro Assembler AS
Links to other great sites:
An oral history of the MC6800
Genealogy of MC68XX Microcontrollers6800 CPU Assembly / Machine Language Books
Motorola 6800 CPU Related Magazine Articles
Various Programming Tools
More Programming Tools
Yet More Programming Tools (FTP)
PhoenixIDE (comercial IDE)
Good Thread
Macro Assembler
An oral history of the MC6800
Genealogy of MC68XX Microcontrollers6800 CPU Assembly / Machine Language Books
Motorola 6800 CPU Related Magazine Articles
Various Programming Tools
More Programming Tools
Yet More Programming Tools (FTP)
PhoenixIDE (comercial IDE)
Good Thread
Macro Assembler