Shared Projects by feilipu

8085 CPU Module - designed for RC2014 Z80 Bus

Am9511A APU Module designed for RC2014.

The Am9511A APU is supported by z88dk, for the RC2014. It provides approximately 3x to 4x speed up compared to software floating point solutions.

The RC2014 Z80 needed to have a fast multiply, and this is it.

design discussion on RC2014 forum

This 128kByte look-up table (LUT) Module allows the RC2014 to directly look up a 16-bit result at a 16-bit address.

The first application for the LUT Module is for an 16-bit result from a 8-bit x 8-bit multiply. It takes 61 clock cycles to return the result, and this is approximately 5 times faster than a shift-add multiply and 2.5 times faster than the best table multiply software routine.

The LUT Module can also hold other tables, including SINE or LOG / LN to 16-bit accuracy, CRC results, or other pre-calculable tables that need to be read quickly.

To multiply Register H by Register L, and return the result in HL, preserving all registers except BC.

mul_hl:
    ld b,h ; 4 multiplier to B
    ld c,0x40 ; 7 operand latch address
    out (c),l ; 12 multiplier from B, multiplicand from L
    in l,(c) ; 12 result LSB to L
    inc c ; 4 result MSB address
    in h,(c) ; 12 result MSB to H
    ret ; 10