Questions tagged [m68k]
For questions about processors in the Motorola 68k (68000 series) range. Commonly used in Amiga, Atari ST, Macintosh, Sinclair QL and Sharp X68000 computers.
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Are there more different ways Motorola 68000 A-line and F-line traps were used than the Classic Mac way and the Lisa way?
On the Motorola 680x0 there are instruction opcodes beginning with an $A nybble or an $F nybble which are not implemented but can be trapped. Some platforms took advantage of these in their ...
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Why does the 68000 have Immediate addressing modes for byte-width instructions?
Motorola's 68000 has an instruction like ori.b #immediate, d0. This particular instruction is encoded as all zeroes, followed by a full 16 bits encoding an 8-bit immediate value. The instruction word ...
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What file format was used for binary executables on Motorola 680x0 Macintoshes?
Current macOS binary executable files use a format called "Mach-O" and prior to that there was the PEF "Preferred Object Format", and Wikipedia says "It was optimised for RISC ...
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Why did Steve Jobs choose the Motorola 68030@25 MHz for the first NeXT Computer in 1988 and not an Intel 80386DX@25 MHz processor?
Was the reason because he knew the 68K from the Macintosh, or were there other reasons that spoke in favor of the 68030 and the additional 68882 floating-point coprocessor?
The i386, along with a 387 ...
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MC68000: address error in initial PC
After an MC68000 processor is released from reset, it fetches the initial stack pointer and initial program counter from the vector table at addresses 0-3 (for the SP) and addresses 4-7 (for the PC).
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GCC to make Amiga executables, including Fortran support?
I have been compiling some command line programs to run on the classic Commodore Amiga. I started with GCC on WinUAE which worked but I realised I didn't have the understanding of the memory stack and ...
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Mac OS Classic install error "the installer document is unusable for installation [...]" (original disks message)
Attempting to upgrade Mac OS Classic 7.5.0 to 7.5.3 via floppies that have been tested successfully on a Performa 460... but things fail ominously on my IIsi with "This is not the correct "⟨...
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Drive icons for LaCie Tsunami
I am restoring a LaCie Tsunami 240 external disk for the Macintosh. I found a replacement Quantum LPS240 and the hardware side is well on its way.
This drive displayed a custom icon in System 7 (a ...
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Were any 680x0 features specifically requested by a customer?
The Motorola 680x0 processor family was used in a variety of systems, including Apple Macintosh, Atari ST, Commodore Amiga, Sharp X68000, and Sinclair QL systems. Had any of these customers wanted a ...
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M68k Big Endian to Little Endian
I'm trying to write a binary file using vasm68k_mot (Motorola 68k) writing File-Size and File-Offset everything goes well, except that M68K is Big-Endian, there's a way I can change to Little-Endian ...
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MC68030: does execution resume during or after cache burst refill?
The MC68030 processor is equipped with dual 256-byte instruction and data caches as well as a "burst" mechanism used to quickly load a cache line from RAM or L2 cache controlled by the ...
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Why are the later revisions of the Motorola 68060 heavily sought after by Amiga fans?
I have come across a few sources online in forums and on YouTube information related to using the Motorola 68060 in Amiga accelerators and the difficulty in sourcing genuine late revision parts. ...
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Porting of software from the m68k family architecture to the DEC VAX
I am looking for impressions, memoirs, articles, guidelines - everything that is possible about the unusual direction of software migration. I am interested in non-Unix related code, and preferably ...
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What performance increase did an Amiga typically get with an FPU?
After seeing this question, I reminisced about how my old Amiga 2500/030 had a 68882 FPU unit. I recall that the Amiga's floating point routine library was smart enough to detect if you had an FPU or ...
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Why were there no 32-bit versions of 65xx CPUs, or 64-bit versions of m68k CPUs?
I don't understand why Western Design Center made the 65816 a 16-bit upgrade to the 6502 but Commodore Semiconductor Group/MOS Technology didn't make their own variant & why neither company made ...
