Cybernetic Micro Systems

Posted on Feb 4, 2014

The CYB-P51 (Rev A) Prototyping Board is designed as a two layer board (without power and ground planes). All components, except the premounted P-51, are through-hole for easy probing and replacement of parts. The board has an oscillator circuit and a crystal circuit pattern, so that either may be used in the test application. A 20 MHz Oscillator

Cybernetic Micro Systems
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is provided, as shown in this photo, and it is connected to 3V at jumper W5, as required by the P-51. See the clock circuits in the user manual for support components for the Xtal circuit. An External pushbutton switch can Reset just the board while in an active ISA slot. The host software must release this hard reset of the P-51 (see P-51 Code RAM in manual). The base address from the ISA host is switch selectable on a DIP-switch that is accessible from outside the computer. The required IRQ is software selectable. See the P-51 user manual for switch settings. On-board Voltage regulator provides 3. 3 volts to the P-51 and oscillator using the computer system`s 5-volt supply. The P-51 I/O pins drive 3. 3 volts and are 5-volt tolerant. All of the ISA-bus signals are brought to a wire-wrap pattern at the bottom of the board, and all the P-51-to-ISA/PC104 signals are also available at that pattern. Alternatively, a micro-controller host could interface to the P-51 at that same jumper. The application signals of the P-51 are brought to a 40-pin wire-wrap pattern in the same configuration as a standard 8051 DIP (with optional IDC pattern). All 8051 signals except X1, X2, Reset, EA, and PSEN are available at the 8051 pattern. Note that a row of GND posts (indicated by white circles) runs along the end of the pattern. Of the excluded 8051 signals, X1 and X2 are available at the Xtal circuit, Reset is replaced by ResetDrv from the...

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