4 ms·

The article describes the 68030 as a 68020 with an added MMU. One of my Amigas a while back had a 68EC030, which is described as a 68030 without the MMU. So, I

The article describes the 68030 as a 68020 with an added MMU. One of my Amigas a while back had a 68EC030, which is described as a 68030 without the MMU. So, I'm wondering what the difference really is between the 68EC030 and the 68020.

BoardsOfCanada 4y ago
I too had an Amiga 4000/030 :) The 68030 added a minuscule cache (256+256) bytes, as well as more efficient bus.
jhfdbkofdchk 4y ago
slightly faster clock owing to the process shrink, and some changes to the bus. They doubled the cache by having a 256 byte cache for instruction and data separately. Instead of a unified 256 byte cache. Kind of a poor showing given they were released 3 years apart.
kjs3 4y ago
The 68030 was a 68020 leaving out a couple of rarely used instructions (I don't recall what) and adding a sort-of-but-not-exact subset of the 68851 MMU, 256 byte cache and some bus interface improvements (sync access). That and process improvements made it more efficient than the 68020. Motorola also upped the clock speeds on the 68030 (up to 50MHz). The EC chips, at least at the beginning, had a defective MMU that was disabled and sold cheaper than a 'full' chip. Fine for the Amiga OS, or embedded stuff. I don't know if they ever made them without the MMU at all. The EC nomenclature extended to the 68040 and 68060, where it meant "no MMU or FPU", and added the LC nomenclature which means "MMU, but no FPU".
- jecel 4y ago
  The software fad of the late 1970s was modular programming as seen in Ada or Modula-2. Intel supported that with its 286 and it was a key feature of the National 32016, so Motorola couldn't be left behind and added support in the 68020. Except that by the time the 68020 came out Unix and C were king and C's dirty hack solution to modularity (#include .h files) was now considered good enough. Intel and National kept full backwards compatibility (to this day, in the case of Intel) but Motorola quietly dropped the stuff from the 68030.

BoardsOfCanada 4y ago

I too had an Amiga 4000/030 :) The 68030 added a minuscule cache (256+256) bytes, as well as more efficient bus.

jhfdbkofdchk 4y ago

slightly faster clock owing to the process shrink, and some changes to the bus. They doubled the cache by having a 256 byte cache for instruction and data separately. Instead of a unified 256 byte cache. Kind of a poor showing given they were released 3 years apart.

kjs3 4y ago

The 68030 was a 68020 leaving out a couple of rarely used instructions (I don't recall what) and adding a sort-of-but-not-exact subset of the 68851 MMU, 256 byte cache and some bus interface improvements (sync access). That and process improvements made it more efficient than the 68020. Motorola also upped the clock speeds on the 68030 (up to 50MHz). The EC chips, at least at the beginning, had a defective MMU that was disabled and sold cheaper than a 'full' chip. Fine for the Amiga OS, or embedded stuff. I don't know if they ever made them without the MMU at all. The EC nomenclature extended to the 68040 and 68060, where it meant "no MMU or FPU", and added the LC nomenclature which means "MMU, but no FPU".

jecel 4y ago
The software fad of the late 1970s was modular programming as seen in Ada or Modula-2. Intel supported that with its 286 and it was a key feature of the National 32016, so Motorola couldn't be left behind and added support in the 68020. Except that by the time the 68020 came out Unix and C were king and C's dirty hack solution to modularity (#include .h files) was now considered good enough. Intel and National kept full backwards compatibility (to this day, in the case of Intel) but Motorola quietly dropped the stuff from the 68030.