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Here is the development board running the site-project�s Digital Clock EPROM. Note the two separate time readouts. The switch to the left of the TIL311 displays allows the 4x digits to look at either the top or the bottom 4 numbers of the display addressing. The processor is in fact running from the 1.6MHz oscillator module immediately to the left of them.

8085 page

Fault Finding

A suggested layout for the development board using all the �options�. Note that there is NO pre-programmed software component on the system. All �programs� are either single-stepped or crystal clocked from RAM, an external EPROM or a programmed EEPROM.

A simple 4x clock multiplier. Useful when programming an EEPROM a step at a time as it generates 4x system clock pulses for the Z80 to move up ONE program step

Data Sheets

The connections to the Z80 (the CPU) showing interfaces to the debounced STEP push button, the STEP / RUN switch, the crystal oscillator and various indicators on the control lines.

Programmer

Ideas for connecting either TIL311 alphanumeric displays with built in drivers, or standard 7 segment types with 7446 drivers. (not so good as you have to �interpret� the values from 10-15 from the �hieroglyphics� on the display.)

A typical divider chain from the chosen oscillator ( in this case 1.6MHz ) to give a switchable timebase of 50 and 100Hz. These are useful for testing and developing such circuits as the site digital clock project (uses 50Hz) or  Stopwatch III (100Hz.)

VIDEO info

Here is the keypad used for the development system.