2 layers98 × 27 mm
2 layers24.9 × 51.6 mm
287-booster
necroware/287-booster9Interposer for 287 FPU with clock mode jumper
- Size
- 24.9 × 51.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 5
- Nets
- 40
- Pads
- 84
- Tracks, vias
- 88, 0
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 3 May 2025
- Updated
- 15 May 2025
Overview
287-booster is an open-source printed circuit board by necroware, from the necroware/287-booster repository on GitHub, published under the CC-BY-SA-4.0 licence. It is a 2-layer board of 24.9 × 51.6 mm with 5 parts on 40 nets, routed with 88 tracks and 0 vias.
Its parts include 2 ICs, 1 resistor and 1 connector. It belongs with the lEDs and displays boards of this library.
README
README.md287 Booster
This is an interposer which adds a jumper which can be used to select the clock divider on a 287 floating point unit. It was designed and open sourced in cooperation with the user i440bx from the German dosreloaded.de community.
Background
Intel 287 co-processors have configuration pin 39 for the clock mode signal (CKM) setup. When this pin is pulled up the chip will use the clock directly. If it is pulled to ground the chip will use a clock divider. The pin has internal pull-down resistor, so it can be left unconnected, which will default the setting to divided clock. Which divider will be used depends on the chip:
- Intel D80287, M80287 run at 1/3 of the clock
- Intel i287XL runs at 1/2 of the clock
- AMD D80C287 runs at 1/3 of the clock
Parts
5| Qty | Value | Footprint | References |
|---|---|---|---|
| 1 | 10K | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1 |
| 1 | 80287 | Package_DIP:DIP-40_W15.24mm_Socket | U1 |
| 1 | Conn_01x02_Female | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J1 |
| 1 | Socket | Package_DIP:DIP-40_W15.24mm | U2 |
The 4 most common of 5 parts.
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Questions
How big is the 287-booster PCB?
It measures 24.9 × 51.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the 287-booster use?
5 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the 287-booster KiCad files?
From the necroware/287-booster repository on GitHub, at the commit this page was made from: the board is kicad/287-booster.kicad_pcb and its schematic kicad/287-booster.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the 287-booster design in my own project?
Its repository publishes it under the CC-BY-SA-4.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).