T68KMB, Tiny68K with RC2014 Expansion Busses

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 MHzoscillator (only 8 MHzoperation is tested)

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.

Target for CP/M-68K ver 1.3

100mm x 76mm 2-layer pc board

Schematic

Gerber photoplots

CPLD design

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