![]() The only part I’ve found was a PIC18F47Q10 MCU, and I must say that it accomplish the previous constrains very well. So I’ve done some searches to find an alternative MCU having three main constraints: must have TTL compatible GPIOs, must be a TH part and cheap too. Unfortunately Atmega MCU GPIO ports are not TTL compatible, and this limitation was solved in the previous boards using a CMOS CPU that under given conditions can accomplish the digital levels of the Atmega MCU.īut here the 68008 CPU isn’t available in CMOS technology at all, so an Atmega MCU cannot be used. Using an Atmega MCU allows to use the friendly Arduino IDE and many ways to flash the MCU, so this is an enabling factor. Those have followed the previous Z80-MBC2 and V20-MBC boards will note that I haven’t used here an Atmega MCU. To allow a real automated toolchain an auto-reset circuit on the breadboard takes the DTR signal from the serial-USB adapter and uses it to reset the MCU (like in the Arduino Uno board), so it is possible reset the breadboard from a batch file running in the PC using a macro of Tera Term. Here a short video with an automated assembler toolchain using Easy68K as assembler and sLoad, a custom SW utility to load from the serial port and execute a Motorola S-record formatted executable: To make the firmware for the PIC18F47Q10 I've used MPLAB X IDE with the MCC plugin. I've used as "companion" MCU a PIC18F47Q10 on a custom board ( PicOne ) I previously made and that it is directly pluggable on breadboards, and with onboard microSD card and USB-serial adapter.: In the first phase of the design I've used a prototype on a breadboard to check the basic "concepts". Having two onboard RS232 serial ports, it allows to connect RS232 terminals like uTerm-S ( ). It has an optional on board 16x GPIO expander, and uses common cheap add-on modules for the SD (HD emulation) and the RTC options. Lite HW configuration option allows to build a 8 system running CP/M-68K. You can choose between two main HW configuration options: Lite or Full. It follows the same "concept" of the previous Z80-MBC2 ( ) and V20-MBC ( ) boards, using a PIC18F47Q10 MCU as EEPROM and "universal" I/O emulator (so a "legacy" EPROM programmer is not needed). The 68k-MBC is an easy to build 68008 CPU SBC (Single Board Computer), using only easy to find TH parts.
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