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builderpages:plasmo:t68kmb [2021/06/23 05:09] – Revision from 2021-06-23 builderpages:plasmo:t68kmb [2026/06/15 13:12] (current) – external edit 127.0.0.1
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 +/* Imported from Wayback Machine
 +   Original URL : https://www.retrobrewcomputers.org/doku.php?id=builderpages:plasmo:t68kmb
 +   Snapshot date: 2025-04-30
 +   Generator    : wayback-archiver
 +*/
 +
 +====== 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/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/t68kmb/t68kmb.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/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/t68kmb/t68kmb_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.
  
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