history - Why did the Motorola 68000 processor family fall out of …
2023年9月25日 · New contenders, such as the Power PC, ARM and MIPS take the 68000 family’s place. Not really - also you forget the NS32k family going away at the same time, being maybe less visible but at least as successful as the 68k. I cannot find in the internet the reason why the 68000 family fell out of favor in the personal computer market.
m68k - What do the "byte-select signals" in the 68000 do ...
The 68000 has instructions for reading or writing words (16 bits) and bytes. In the latter case, it needs to be able to tell the world which half of the databus it is reading or writing. According to the 68000 user manual (table 3-1), when the process is reading or writing the data bus the LDS and UDS signals are used to tell the world which ...
m68k - Why are old CPUs like MOS Technology 6502 and …
2020年10月17日 · The 68000 and 68020 are sometimes used where interrupt latency is less of a concern. 3: Ability to run at "micropower", ie. less than a milliwatt, in embedded applications that demand extremely long battery life, sometimes on the order of several years (eg. 6502s are used in pacemakers). This practically demands a "fully static" CMOS ...
68000 and memory access speed - Retrocomputing Stack Exchange
2017年5月13日 · Looking at figure 4-1 of the 68000 datasheet, a simple byte read or write bus cycle takes 4 CPU cycles (8 bus states; each state is half a cycle), and the simple word read or write bus cycles in figure 5-1 also takes 4 cycles, so indeed RAM access time was 2 MHz for a 8 MHz CPU clock. Note that the whole cycle determines bus access rate: The ...
history - Did IBM originally plan to use the 68000 in the PC ...
2020年11月14日 · IBM's original plan had been to design the personal computer around Motorola's 6800 processor at its Austin, Texas research center. IBM marketing had arranged for the PC to be sold through the stores of Sears, Roebuck & Co., and the deal teetered in the balance as Motorola's 6800 along with its support chips slipped in schedule.
motorola 68000 - What limited the use of the Z8000 (vs. 68K and …
The 68000 family was clearly designed with an eye towards high-level language programming. The architecture was 32-bit in concept, although the original implementations were 16-bit. It had "flat" unsegmented memory addressing, which is always easier for compilers, and could address 16MiB of RAM, which increased to 4GiB in later members of the ...
Replacing 80286 with 68000 - Retrocomputing Stack Exchange
2017年12月29日 · All 286 code in ROM or on disk would have to be replaced with suitably equivalent 68000 code. Or add a 286 emulation :) The packages are different. The 286 is in a square package whereas the 68000 is in a DIP; something would have to be done to physically wire up the replacement chip.
Swapping endian-ness on the 68000 - Retrocomputing Stack …
2020年6月29日 · 11. In the 80s, the two great 16/32-bit desktop CPU architectures were the x86, used in the IBM PC and compatibles, and the 68000, used in the Amiga, Atari ST, Macintosh, early UNIX workstations and really most things that were not trying to run MS-DOS. With the rapid growth of MS-DOS, there inevitably developed an interest in running it on ...
What makes MOVEQ quicker than a normal MOVE in 68000 …
2019年7月18日 · 22. I'm "re-learning" 68000 assembly language and came across the "MOVEQ" command that is labeled "MOVE QUICK". According to the NXP Programmers Reference Manual (reference below), the command MOVEQ (MOVE QUICK) is described as: Moves a byte of immediate data to a 32-bit data register. The data in an 8-bit. register as it is transferred.
How does states, bus cycles and clock cycles differ in the M68000?
2019年7月24日 · For an 8Mhz 68000, there are 8,000,000 clock cycles per second. A bus cycle is the complete set of states that describes a bus interaction — most normally a read or write, and usually 4 cycles / 8 states long.