# Tag Info

4

The missing piece for me was the math background. Will try to connect math and actual implementation. The fully explanation is given by user3840170's post (hope my post is complementary to user3840170's brilliant post). As example, let me calculate 127:10. The result is 12 and reminder is 7: 127 - 10 * 2^5 = -193  * 2^3 127 - 10 * 2^4 = -33  * 2^4 ...

1

Will the 8080 tests be valid 8080 assembly code? Only if they do not contain any undocumented 8080 opcodes, they will remain valid after Z80 disassembler.

43

As was said in the comments, this is the binary long division algorithm. The long division is performed by carefully juggling the bits between the registers and the carry flag. The algorithm is probably best analysed by looking at each half of the loop as a whole. MOV D, A MOV A, E RAL MOV E, A DCR C JZ exit The first half of the loop shifts ...

14

Don't understand purpose of SUB B/ADD B It's an underflow handling SUB B ; Subtract divider JNC loop_1 ; No underflow -> Continue ADD B ; Correct underflow JMP loop_1 ; -> Continue B is subtracted from A. If there is no underflow (A was larger than B) then the loop continues with the new (positive) value of A. A is restored to ...

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