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Stuart Conner's Mini-Cortex board build

Stuart Conner's Mini-Cortex board build

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Stuart Conner's Mini-Cortex design, slightly modified.

Modifications:

  • Low-height crystal is less vulnerable to knocks
  • Omit video module socket. C10 and C15 for now
  • Omit CF card for now
  • Omit memory mapper

Currently held up because I can't find the 9902 chips I bought in 2020!

CORTEX-edited-EQN.txt

Edited to a form to aid my understanding. Untested, unverified.

plain - 1.50 kB - 04/16/2022 at 23:25

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CORTEX-EQN.txt

Stuart's logic equations. They work, but use the "dual" of what I would expect, so I found them hard to follow.

plain - 746.00 bytes - 04/16/2022 at 23:03

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CORTEX.JED

JEDEC file for programming the GAL. Generated from Stuart's equations.

jed - 3.11 kB - 04/16/2022 at 22:59

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Adobe Portable Document Format - 69.28 kB - 04/11/2020 at 23:30

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  • Construction

    Keith04/27/2022 at 00:29 0 comments

    2022-04-25

    Soldered on the Mini Cortex board:

    • U1 TMS9995 socket
    • U3 74LS14
    • U6 74LS688
    • U9 omit FTDI module and use FTDI cable instead
    • U10 74LS259
    • U12 74LS74
    • U13 74LS112
    • U14 74LS138

    2022-09-30

    • U2 memory mapper socket, DIP40.
    • U4 32K ROM socket, DIP28.
    • U5 512K RAM socket, DIP32.
    • U8 9902ANL, DIP18.
    • U11, DIP24 socket for 22V10.
    • X1 crystal, 12 MHz or near.
    • J3 for FTDI cable.

    2022-10-02

    • R3 and R13 (LED resistors)

    2022-10-16

    • Program 32K EEPROM AT28C256 with firmware.
    • Program U11 PAL ATF22V10C.

    To do:

    • Find and fit TMS9902 serial chip
    • Test BASIC operation
    • Find and fit memory mapper chip
    • Fit compact flash

  • Project Log

    Keith09/28/2019 at 22:53 0 comments

    2019-09-23

    Ordered TMS9995, TIM9904 and TMS9929A from Chinese source.

    TMS9929A is a PAL video chip, but might be useful on a simple video display board. Might make one board support multiple chips e.g. a 6847 as well.

    2019-10-09

    TMS9995 and TIM9904 chips arrive.

View all 2 project logs

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