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 Snapshot date: 2025-04-30
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T68KMB, Tiny68K with RC2014 Expansion Busses

Introduction

T68KMB is T68KRC with 3 RC2014 expansion busses added. It is software compatible with T68KRC.

Motorola 68000 CPU

MC68681 DUART, port A is the console operating at 38400 baud, 8N1, with CTS/RTS hardware handshake.

Altera EPM7128 CPLD contains the glue logic:

State machine to load 32K serial flash when powered up or with a reset,

DRAM controller for the 2-megabyte DRAM,

Hidden CAS-before-RAS refresh in hardware, no software overhead required,

memory decoder,

Interrupt controller,

Bus Error watchdog timer,

8-16 MHz oscillator

32Kbyte serial flash, 24C256 as the boot device.

Second 32K serial flash that can be programmed in-situ and serves as the alternate boot device with just one jumper change.

44-pin edge connector interfaces to a low-cost IDE-CF module

HY5118164 1Mx16 DRAM

I/O expansion port compatible with RC2014 I/O bus interface.

7-segment LED display as visual indicator of board operations.

Three RC2014 expansion busses

I2C connector for 128×64 OLED display

Target for CP/M-68K ver 1.3

102mm x 102mm 2-layer pc board

T68KMB has the same design approach as T68KRC. Refer to T68KRC Description section for more details.

Schematic

T68KMB software is compatible to T68KRC. Please refer to software section of T68KRC.