NEO-AES4-1 board

Seems to be the sixth and latest board revision.

Some (all ?) units appear to be heavily shielded with a metal cover and conductive coating on the plastic shell.

Differences with previous revisions:

• The power supply circuit was (finally) moved next to the power connector.
• Most through-hole chips were replaced by their surface mount versions.
• The PLCC version of the 68k CPU was used. Also tiny Z80.
• The SP1 ROM is an OTP part.
• Resistor networks were added on bus lines, maybe as an attempt to reduce radiated noise.
• TC9018P composite sync generator.
• [[Signal names#{{{2}}}|SYNC]]/NEW-SYNC jumper.
• [[Signal names#{{{2}}}|BNKB]]/RBNKB jumper.