HP 64751 User Manual page 57

Chapter 2: Plugging into a Target System
Step 3. Select the emulator clock source
2 To select the 32.768 KHz crystal internal to the emulator, insert the jumper module such that pin 1 of
the module aligns with pin 1 of the socket. The target system MUST drive MODCK high (or allow a
pullup resistor in the emulator to pull it high) during reset to enable the 68340 VCO and programmable
clock mode.
To select an external (target system) TTL oscillator, rotate the jumper module 180 degrees such that pin 8
of the module aligns with pin 1 of the socket. The target system MUST drive MODCK low during reset
to enable the 68340 to use the EXTAL signal as the clock source.
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