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==== Table of Contents ====

[[#t68kmb_tiny68k_with_rc2014_expansion_busses|T68KMB, Tiny68K with RC2014 Expansion Busses]]

[[#introduction|Introduction]]

[[#features|Features]]

[[#description|Description]]

[[#design_information|Design Information]]

[[#software|Software]]

====== T68KMB, Tiny68K with RC2014 Expansion Busses ======

===== Introduction =====

T68KMB is [[builderpages:plasmo:t68krc_r01|T68KRC]] with 3 RC2014 expansion busses added. It is software compatible with T68KRC.

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=dd0672&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/t68kmb/t68kmb.jpg|{{https://www.retrobrewcomputers.org/lib/exe/fetch.php?w=600&h=413&tok=0a2229&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fbuilderpages%2Fplasmo%2Ft68kmb%2Ft68kmb.jpg?600x413|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_t68kmb_t68kmb.jpg}}]]

===== Features =====

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

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=476e79&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/t68kmb/t68kmb_annotated.jpg|{{https://www.retrobrewcomputers.org/lib/exe/fetch.php?w=500&h=343&tok=f4cb80&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fbuilderpages%2Fplasmo%2Ft68kmb%2Ft68kmb_annotated.jpg?500x343|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_t68kmb_t68kmb_annotated.jpg}}]]

===== Description =====

T68KMB has the same design approach as T68KRC. Refer to T68KRC [[builderpages:plasmo:t68krc_r01|Description section]] for more details.

===== Design Information =====

Schematic

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:t68kmb:t68kmb_rev0_gerber.zip|Gerber photoplots]]

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:t68krc:t68krc_r01:t68krc_cpld.zip|CPLD design files]]

==== Software ====

T68KMB software is compatible to T68KRC. Please refer to [[builderpages:plasmo:t68krc_r01|software section]] of T68KRC.