Posted By
JamesD
on 2017-02-14
08:03:38
|  Re: A mathematical demo
Please pardon the long winded response.
The 68000 is not an upgrade to the 6800, it is completely different.
The Z8000 is not a derivative of the Z80, it is completely different.
The 68000 still lives on in the Coldfire series of chips, and the Apollo FPGA core which is many times faster than a 68060. The Vampire series of Amiga accelerator boards are based on the Apollo.
The Z8000 is pretty much a distant memory even though it was technically better than the Z80. A pipelined version would have been pretty fast. A pipelined version would be very RISC like.
The 6809 is not an upgrade to the 6800 either, it is partially source compatible with the 6800 though and is easy for a 6800 programmer to adapt to.
The Hitachi 6309 is an upgrade to the 6809 that adds an instruction prefetch, additional instructions, a divide, and some 32 bit support.
The 6801/6803, IS an update to the 6800, but it is a microcontroller with built in hardware.
It will run 6800 code that doesn't conflict with the built in hardware.
It optimizes many instructions for faster execution, adds the D register which combines A & B to form a 16 bit register, it adds a multiply instruction, and it simplified hardware design requirements.
It predates the 6809.
The 6803 was used as the main CPU in the MC-10, and Alice systems. It also served as a controller for every device that attached to the Adam, and served as a keyboard controller in some Thomson systems
The Hitachi 6303 is a slight upgrade to the 6803, it offers some new instructions.
The 6801/6803 was updated with the 68HC11 and 68HC12, which added some instructions and additional index register(s).
The 6800 was used heavily as a controller, especially with the automotive industry.
It was more of a competitor to the 8080, and was the basis of systems based on the Flex OS. Flex is pretty much CP/M for the 6800. It had simpler power requirements than the 8080 which made it cheaper to design for.
The APF Imagination machine was based on the 6800, as was the Panasonic JR-200, though the JR-200 uses a clone of the 6802 which has a few of the 6803 enhancements.
The automotive industry moved on to the 6809, 68HC11, 68HC12, etc... and derivatives of these are still used in some devices today, though they may be FPGA or custom ASIC based.
As for Z80 derivatives...
The Z280 has a 16 bit ALU and is pipelined. It was originally the Z800 which was announced in the 1983/4 data book, but there were some problems with it, and it didn't make it to market until 1987 with a name change.
Tthe R800 in the MSX Turbo R was supposedly derived from the Z800, and it's pretty fast.
The Hitachi HD64180 was the first real Z80 upgrade available in 1985l. It was licensed back to Zilog as the Z180.
A 6 MHz 64180 is supposed to run the same speed as an 8 MHz Z80.
The Z80 has a 4 bit ALU, but the 64180 is 8 or 16 bit, I forget which. It also has an instruction prefetch, a multiply, built in ports and timers, built in DMA, and the ability to address 512K of RAM using an MMU.
The Z180 is slightly more compatible with the Z80 from an interface design standpoint, and is available in 30+ MHz versions to this day.While it is a microcontroller with built in ports, you could set the address of the ports so they wouldn't conflict with existing hardware. At least if one of the selectable blocks was not taken.
Several CP/M systems were based on the 64180, as was one MSX machine (it also had a Z80 for compatibility). At least one of the CP/M systems was clocked at over 9 MHz... which would be about like a 12 MHz Z80. A later Z280 system was clocked at 12 MHz and would have been very fast for a Z80 system at that time.
Most modern Z80 derivatives use the additional instructions from the Z180.
The Z380 offered additional memory handling, multiple register banks, stack relative addressing, and a few other enhancements. I think it was aimed at multi-user machines running separate programs in their own memory. The stack relative addressing was certainly nice for compiler support, but I'm not sure any other CPUs support that.
The eZ80 is source compatible with the Z180, but it won't run Z80 object code
Other pipelined implementations from several manufacturers are also significantly faster, though most only use a single interrupt or other changes so they can't just drop in place of a Z80.
The fastest Z80 derivatives are probably Verilog or VHDL cores. A couple of those are supposed to be able to work in custom silicon at 200 MHz or more, but I've never seen a stand alone CPU that fast.
As for the 65816...
This Benchmark just measures one area of performance. It's an incomplete picture of what a CPU can really do. The mode switching required to go between 8 and 16 bits make it slower than the 6809 for mixed 8 and 16 bit code. I don't think it would help this benchmark, but there are clearly situations where it is faster than the 6502.
The Atari version of my 64 column graphics text code with a 65816 scroll is about the same speed as the 3.5 MHz Z80 in the VZ200. The scroll loop that hurt the 6502 vs the slower clocked 6803, now moves 16 bits at a time on the 65816 and it's higher clock speed suddenly shows.
The 16 bit support, stack relative addressing, and larger stack make it much better for compiled languages.
One case I can think of where the 65816 would be much faster than the 6502, is Apple Pascal. Apple Pascal is actually UCSD Pascal (portable to about any machine with 64K RAM). The P-Code interpreter is heavily oriented towards 16 bits (as is Pascal), and the 65816 would require significantly fewer instructions than the 6502.
The larger memory support of the 65816 would also allow a full 64K to be dedicated just for code, and the larger stack could support a lot deeper recursion. Additional code modules could be cached in the rest of RAM and would be much quicker to access than paging RAM with the 6502.
I would think an overall speed improvement of 20% or more would be very likely, and 50% might not be out of the question... but I wouldn't bet on it.
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