paul@78 | 1 | Files
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paul@78 | 2 | -----
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paul@78 | 3 |
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paul@78 | 4 | The cartridge_board_measurements.svg file was converted to the form defined by
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paul@78 | 5 | cartridge_board.svg by removing dimension details, setting stroke widths to 0
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paul@78 | 6 | for all objects, converting shapes to paths, performing a union operation on
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paul@78 | 7 | the main board shape with the rectangles providing material for the edge
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paul@78 | 8 | connector curvature (see below), then using the difference operation to remove
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paul@78 | 9 | all cutout shapes. This should leave a single path object defining the board
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paul@78 | 10 | minus the cutouts.
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paul@78 | 11 |
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paul@78 | 12 | The cartridge_board_rear.svg file takes the board shape, flips it
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paul@78 | 13 | horizontally, and converts all curves to lines by adding more points (three
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paul@78 | 14 | times appears sufficient) and then using the curve-to-line operation. This
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paul@78 | 15 | file is then exported to DXF (version 14) and produces the
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paul@78 | 16 | cartridge_board_rear.dxf file.
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paul@78 | 17 |
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paul@78 | 18 | Importing the cartridge_board_rear.dxf file into KiCad with the connectors
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paul@78 | 19 | aligned to a 0.127mm grid, the offsets 60.445mm (3in - 15.755mm) and 127mm
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paul@78 | 20 | (5in) can be used. The DXF file is suitable for designs where the rear of the
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paul@78 | 21 | board is the focus, typically because that is the side on which components
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paul@78 | 22 | will be mounted.
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paul@78 | 23 |
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paul@78 | 24 | PCB Measurements
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paul@78 | 25 | ----------------
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paul@78 | 26 |
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paul@78 | 27 | The cartridge_board_measurements.svg file summarises the details below.
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paul@78 | 28 |
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paul@78 | 29 | ROM cartridge board width is 84.85mm, height is 62.5mm.
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paul@78 | 30 |
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paul@78 | 31 | Mounting holes are at 4.975mm and 79.875mm horizontally with small holes
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paul@78 | 32 | having a radius of 1.6mm and large holes having a radius of 3.75mm. Small
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paul@78 | 33 | holes appear at 5.875mm and 45.875mm from the top of the board (56.625mm and
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paul@78 | 34 | 16.625mm from the bottom). Large holes appear at 36.875mm from the top of the
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paul@78 | 35 | board (25.625mm from the bottom).
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paul@78 | 36 |
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paul@78 | 37 | Two mounting slots of 2.2mm width are centred on 14.825mm and 70.025mm
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paul@78 | 38 | horizontally. The front left (rear right) slot starts at 23.475mm from the top
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paul@78 | 39 | of the board (39.025mm from the bottom) and ends at 35.575mm (26.925mm), then
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paul@78 | 40 | being extended by a circular cutout of 1.1mm radius. The front right (rear
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paul@78 | 41 | left) slot starts at the same vertical location but ends at 33.075mm
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paul@78 | 42 | (29.425mm), being extended by the 1.1mm radius cutout. Thus, it is 2.5mm
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paul@78 | 43 | shorter.
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paul@78 | 44 |
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paul@78 | 45 | Edge Connector Pads
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paul@78 | 46 | -------------------
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paul@78 | 47 |
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paul@78 | 48 | Edge connector width is 56.5mm, height is 11.85mm.
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paul@78 | 49 |
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paul@78 | 50 | The edge connector on the Advanced Computer Products cartridges (and
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paul@78 | 51 | presumably the Acorn ones) curves into the lower edge of the main board area.
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paul@78 | 52 | This curvature has a 1.1mm radius.
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paul@78 | 53 |
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paul@78 | 54 | AppNote-014.pdf indicates that "Cartridges plug into a 44 way gold plated edge
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paul@78 | 55 | connector arranged on each side of a 0.05 inch slot as 22 ways of 0.05" x 0.5"
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paul@78 | 56 | on 0.1" centres."
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paul@78 | 57 |
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paul@78 | 58 | Note that 2.54mm = 0.1in. Thus, "0.1" centres" indicates a spacing of 2.54mm.
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paul@78 | 59 | The connectors are therefore 1.27mm x 12.7mm. The slot is 1.27mm (0.05in)
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paul@78 | 60 | wide, presumably requiring such a board thickness.
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paul@78 | 61 |
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paul@78 | 62 | 1.58mm margins from the edges to the centre of the first connector
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paul@78 | 63 |
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paul@78 | 64 | 2.54mm between the centres of each connector
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paul@78 | 65 |
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paul@78 | 66 | 22 connectors gives...
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paul@78 | 67 |
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paul@78 | 68 | (22 - 1) * 2.54mm + 2 * 1.58mm = 56.5mm
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paul@78 | 69 |
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paul@78 | 70 | The edge connector has an offset of 14.175mm from the left edge of the board.
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paul@78 | 71 |
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paul@78 | 72 | (84.85mm - 56.5mm) / 2 = 14.175mm
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paul@78 | 73 |
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paul@78 | 74 | The first connector has an offset of 15.755mm from the left edge of the board.
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paul@78 | 75 |
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paul@78 | 76 | 14.175mm + 1.58mm = 15.755mm
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paul@78 | 77 |
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paul@78 | 78 | The base of the connectors has an offset of 62.5mm from the top of the board,
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paul@78 | 79 | being the base of the board.
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