Tag: period project

Published twelve-chip Motorola 6800 teaching coprocessor that takes control of the Apple II bus.

This is a published construction project, not a current kit or finished product. The paper supplies a circuit diagram and tested monitor listing but no PCB layout, Gerbers, bill of materials, or explicit reuse license. A builder must recreate the board, source period logic, program a 2716 EPROM, and validate timing and bus loading.

Published 1985 Apple II coprocessor prototype with a 68020, optional 68881, 32K SRAM, and boot EPROM.

Treat this as a historical experimental build, not a safe drop-in design. The creators used custom wire-wrapped and insulation-displacement construction rather than a published PCB. Later design notes estimate roughly 1 A typical and as much as 1.5 A from +5 V even though the Apple II specifies 500 mA shared by all peripheral cards, and they identify excessive data-bus loading. A faithful build needs its own engineering review and likely a redesigned power and bus interface.