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Need help with encoding
http://easy68k.com/EASy68Kforum/viewtopic.php?f=5&t=1587
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Author:  Kecks73 [ Sat Mar 04, 2017 4:13 pm ]
Post subject:  Need help with encoding

Hello every one
I need some help with my study. I have to encode some easy68k commands.
One example:
movem.L (a7)+, d2/a0
I encoded the first part of the command:
4CDF. But I couldn't encode the "follow-word" (In Gemran it's the "Folgewort". I don't know the exact technical meaning of it in english, sorry)
The full and correct encoded command of movem.L (a7)+, d2/a0 is:
4CDF 0104
How do you get the 0104?
Thanks for everyone who is helping :)

Author:  profkelly [ Tue Mar 07, 2017 10:06 pm ]
Post subject:  Re: Need help with encoding

From the 68000 documentation:

MOVEM

Instruction Format:
Code:
15  14  13  12  11  10   9   8   7    6   5   4   3   2   1   0
 0 | 1 | 0 | 0 | 1 |dr | 0 | 0 | 1 |size|    MODE  | REGISTER

dr field - Specifies the direction of the transfer.
0 - Register to memory.
1 - Memory to register.

size field - Specifies the size of the registers being transferred.
0 - Word transfer
1 - Long transfer

Mode and Register specifies the addressing mode and registers used. Refer to table in the programmers reference manual.

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