ALU Design v0.1

The ALU Design v0.1 is a slight variation on the previous ALU (bits 0..3) design which means the same board design can be used for both the ALU bits 0..3 and the ALU bits 4..7 boards.

The modification adds the A3 and B3 from the ALU board's input buses to the board's output bus so that these input values form part of the input into the shifter and flags board.

Bits 7 of the A and B inputs into the ALU are required by the shifter and flags board to calculate the overflow flag. The design means both bits 3 and 7 of the ALU input will go the the shifter and flags board but the board design will simply ignore the bits from the ALU bits 0..3 board.

The Eagle CAD schematic for ALU Design v0.1 can be downloaded here.

The Eagle CAD board for ALU Design v0.1 can be downloaded here.

The bill of materials
Part     Value          Package      Library  Position (inch)       Orientation

C1       0.1uF          C050-030X075 rcl      (0.55 0.6)            R0
C2       0.1uF          C050-030X075 rcl      (0.95 0.6)            R180
C4       0.1uF          C050-030X075 rcl      (2.35 0.6)            R0
C5       0.1uF          C050-030X075 rcl      (0.9 2.95)            R90
C6       0.1uF          C050-030X075 rcl      (1.5 2.95)            R90
C7       0.1uF          C050-030X075 rcl      (2.1 2.95)            R90
C8       0.1uF          C050-030X075 rcl      (3.55 1)              R270
C9       0.1uF          C050-030X075 rcl      (3.55 2.15)           R270
C10      10uF           E5-5         rcl      (0.9 0.3)             R90
C11      0.1uF          C050-030X075 rcl      (2.7 2.9)             R90
C12      10uF           E5-5         rcl      (3.2 2.7)             R270
CONTROL                 1X08         pinhead  (1.85 0.3)            R180
IC1      74HC08N        DIL14        74xx-eu  (1.2 2.5)             R270
IC2      74HC32N        DIL14        74xx-eu  (1.8 2.5)             R270
IC3      74HC86N        DIL14        74xx-eu  (2.4 2.5)             R270
IC4      74HC157N       DIL16        74xx-eu  (1.2 1.15)            R90
IC5      74HC153N       DIL16        74xx-eu  (3.2 1.9)             R270
IC6      74HC153N       DIL16        74xx-eu  (3.2 0.75)            R270
IC7      7483N          DIL16        74xx-eu  (1.8 1.15)            R90
IC8      74HC157N       DIL16        74xx-eu  (0.55 2.5)            R270
IC9      74HC153N       DIL16        74xx-eu  (2.4 1.15)            R90
IC10     74HC86N        DIL14        74xx-eu  (0.6 1.2)             R90
INPUT                   1X08         pinhead  (0.2 1.4)             R90
JP4                     1X02         pinhead  (0.6 0.2)             R180
JP5                     1X02         pinhead  (3.45 2.8)            R0
OUTPUT                  1X08         pinhead  (3.75 1.45)           R270