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10

The rounding capability is useful when doing fixed point math with exactly eight fractional digits. For example, supposing that the number in A is a fixed-point number with 2 fractional digits, and the number in B is a fixed-point number with 6 fractional digits: lda #%00100010 A=%001000.10=8.5 ldb #%11110000 B=%11.110000=3....


5

Like it says, it is useful for rounding the most significant byte. If you are only interested getting a 8-bit answer, and thus want to discard the low 8 bits of the multiplication. If the answer would be 234.9 for example, taking the high 8 bits directly would truncate to 234. Rounding to 235 would be closer to result. It could be accomplished by a 16-bit ...


5

TL;DR: It allows the use of MUL as part of a Multiply-Accumulate operation, by providing the rounding factor from the multiplication for a follow up addition. The Long Read: It's not about (mathematical) rounding of the result as 16 bit value, as a multiplication will never have any remainder. It's about supporting rounding toward an 8 bit value as it is ...


4

The Microware Assembler has no way to inform you of why it is issuing a warning. It keeps track of the total number of warnings, and also of the number of warnings on each line. If a line has any warnings, then when it is listed the assembler puts the "W" flag on that line1. At the end of the listing, the assembler prints the total number of warnings. ...


5

The boards are essentially "serial to parallel converters," but probably not of any type anybody here is familiar with. A manual has been found that describes two devices, the MSD-1 Multiple Status Display and the MDC-2 Multiple Direct Command Option, used with the Moseley Associates Inc. MRC-2 system, a microprocessor-based system for monitoring and control ...


7

The skew between min and max propagation delays was a lot larger in old multi-micron NMOS processes (an understatement). The digital rise and fall times could be quite asymmetric. This made transistor sizing to prevent both setup and hold timing violations more difficult. Arithmetic combinations of a two phase (or more) or quadrature clocks allow creating ...


13

E is used for memory selection in a similar way as 6502 do (or 6800 phi2). Q should be used as a signal "data stable" (due to "The MC6809 Cookbook"). Let me quote: Addresses from the MPU will be valid with the leading edge of Q. Data is latched on the falling edge of E. It is called the "quadrature clock" and it is used sometimes in other systems too. ...


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