Motorola 6800
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Motorola 6800
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Re: Motorola 6800
#2With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky).
I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
Re: Motorola 6800
#3With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky). I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
The 6809 had two 16 bit index registers, PC-relative addressing, and upper half of the stack and data page address was taken from special purpose registers instead of hardwired. It should be a fairly straight forward compiler target. On the other hand it was late to the game, expensive and not (much) faster than 8bit microprocessors. The 6502 very cheap, fast enough when it came out, but a really annoying compiler target.
Re: Motorola 6800
#4I just finished an undergraduate class on microcontroller applications that used a MC68HC12 dev board. We coded in Assembly and then later in C.
I'm curious, is this a typical platform in other computer engineering programs in the US?
Re: Motorola 6800
#5With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky). I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
Some of that can be gleaned from this benchmark, published in Byte, in 1981: https://en.wikipedia.org/wiki/Byte_Sieve
Results for a few 8/16 bit processors are here (and on subsequent pages): https://archive.org/details/byte-magazine-1981-09/page/n193/...
Re: Motorola 6800
#6With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky). I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
I just don't think any of the 8-bits made good compiler targets. At least not C compilers. Not enough registers, even in the 6809.
Re: Motorola 6800
#7With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky). I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
The 6809 had two 16 bit index registers, PC-relative addressing, and upper half of the stack and data page address was taken from special purpose registers instead of hardwired. It should be a fairly straight forward compiler target. On the other hand it was late to the game, expensive and not (much) faster than 8bit microprocessors. The 6502 very cheap, fast enough when it came out, but a really annoying compiler ta…
I had a TRS-80 Color Computer when I was kid which had one major drawback: it could only display 32 characters across the screen compared to 40 characters for the Apple ][, C64 and most others at the time.
The Coco could run an operating system called OS-9 which was Unix-influenced and came with a good C compiler and also a bytecode interpreted structure basic called BASIC09.
I know C compilers were really popular among CP/M users running the Z-80 and 8080 chips and also on the IBM PC which had a segmentation system to reach beyond 64k that I thought felt really elegant in assembly language but was awkward for compilers.
Where OS-9 had all the above beat was that it was a real multitasking OS and I had two terminals plugged into my coco in addition to the TV console and could use it like a minicomputer.
When I switched to an IBM PC AT compatible my favorite programming language was Turbo Pascal which adds everything missing from Pascal to do systems programming. I switched to C when I went to college because that was supported on the the various UNIX workstations they had.
Re: Motorola 6800
#8I just finished an undergraduate class on microcontroller applications that used a MC68HC12 dev board. We coded in Assembly and then later in C. I'm curious, is this a typical platform in other computer engineering programs in the US?
At our company we still use a MC68HC11 for an industrial device.
Re: Motorola 6800
#9I built a small multitasking kernel with a friend with a 68000 (m68000) in college. We implemented it on breadboards, I think with 30 or so feet of jumpers [0]. I had very little prior embedded experience, so it was trial by fire.
It was a wonderful introduction to how kernels work (or at least concurrency and scheduling) at their most basic level, without having to deal with the complexity of virtual address spaces, memory protection, or the byzantine bring-up dance of register prodding that x86_64 needs. It prepared me well for my operating systems class the next year, and as far as I can tell, was the eye-catcher project that got me an internship on a team doing kernel development the following summer.
The instruction set is also a dream. Super CISC-y, yet more enjoyable (and IMO easier to grok) than x86. Take a look: http://wpage.unina.it/rcanonic/didattica/ce1/docs/68000.pdf
My favorite is DBcc - "Test condition, decrement, and branch". All in one instruction.
[0] - https://i.imgur.com/MKD7wTv.jpg
Here's the code - I have no idea how it works anymore, and I believe it's incomplete compared to what I had running. The complete code archive I think is lost to time - https://github.com/dymk/68k/blob/master/projects/libraries/l...
My friend wrote up a much more comprehensive document on the build:
https://github.com/ZigZagJoe/68k
https://docs.google.com/document/d/1ejW_Ist19tIXeA5HtEWixaLo...
Re: Motorola 6800
#10With the optics of _compiled_ code, how do the various 8-bitters stack up? (6809/6811, 65C02, Z80, H8, ...)? One would have to account for the frequency allowed by the ISA at iso-technologies (which makes including AVR somewhat tricky). I only have experience with Z80 and 65C02 and I believe the consensus is that a 4 MHz Z80 beats a 2 MHz 65C02, but neither is a particularly nice compiler target.
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