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Post by GiGaBiTe on May 29, 2009 1:50:30 GMT -5
CMOS versions of the 68000 are MC68HC000 or HD68HC000 for the Hitachi part. Regular 68000s are just MC68000P8 The LC thing was used in the later 68040 to indicate the lack of a FPU. Motorola later made LC versions of most of their chips. I don't remember an LC 68000, though. I thought they only made LCs back to the 020. The A1200 uses an LC 68020. LC indicates the lack of an FPU. Since the 68000, 68010, 68020 and 68030 didn't have integrated FPUs (they all had 68881 or 68882 external socketed FPUs), they never had the LC designation. They did have a 68EC0x0 which was basically the same as a regular 680x0, but with a 24 bit address bus and lack of a MMU.
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Post by jlf65 on May 29, 2009 19:41:09 GMT -5
Motorola later made LC versions of most of their chips. I don't remember an LC 68000, though. I thought they only made LCs back to the 020. The A1200 uses an LC 68020. LC indicates the lack of an FPU. Since the 68000, 68010, 68020 and 68030 didn't have integrated FPUs (they all had 68881 or 68882 external socketed FPUs), they never had the LC designation. They did have a 68EC0x0 which was basically the same as a regular 680x0, but with a 24 bit address bus and lack of a MMU. Oh! Right... EC version. Yeah, you're right. I confused the two. Sorry about the mixup. Must been doing acid. ;D
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Post by Tiido on May 30, 2009 8:48:15 GMT -5
are the EC versions behaving differently from non EC versions ? Saturns have EC 68000 in them, I was thinking of doing a swap... putting EC into MD and non EC into Saturn...
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Post by jlf65 on May 30, 2009 14:29:43 GMT -5
Originally, EC just meant the FPU and MMU didn't work - it WAS there, but was malfunctioning in an unspecified way. It WAS active! many people have gotten LC and EC parts and used them in place of the regular parts... if you're lucky, the flaw in the MMU or FPU wasn't fatal; if you were REALLY lucky, the part appeared to function normally. Motorola's manual said this about it: "Part will do unspecified actions for an unspecified amount of time."
When they added the EC label to later parts, it meant it had a couple extra registers associated with memory map control, if I remember correctly. Download the manual for details (all Motorola, now FreeScale, manuals are available online for download).
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Post by GiGaBiTe on May 31, 2009 9:00:16 GMT -5
are the EC versions behaving differently from non EC versions ? Saturns have EC 68000 in them, I was thinking of doing a swap... putting EC into MD and non EC into Saturn... "The later evolution of the 68000 focused on more modern embedded control applications and on-chip peripherals. The 68EC000 chip and SCM68000 core expanded the address bus to 32 bits, removed the M6800 peripheral bus, and excluded the MOVE from SR instruction from user mode programs.[4] In 1996 Motorola updated the standalone core with fully static circuitry drawing only 0.5 µW in low-power mode, calling it the MC68SEC000." You would face several serious problems if you did that. The 68EC000 has a 32-bit address bus, while the 68000 only has a 24-bit bus. You couldn't replace the 68EC000 in the Saturn with an older 68000 due to the lack of the bus width. You could probably put a 68EC000 in a Genesis, if it allowed 8 of the address lines to not be connected (like the SH2 in the 32x). I think the Genesis runs in supervisor mode all the time, so removing the MOVE from SR shouldn't cause any problems. The problem would really be the code. Many people used the higher 8 bits of the address bus as flags, which would cause incompatibility with the 32 bit 68EC000. Since there were so many developers on the Genesis, some games may work while others just crash.
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Post by Tiido on May 31, 2009 11:37:30 GMT -5
68EC000 does not have 31 or 32 address lines, only 24, 68000 has 23...
What will make things totally incompatible without further mods is different pinout.
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