/* Imported from Wayback Machine
   Original URL : https://retrobrewcomputers.org/doku.php?id=builderpages:plasmo:crc65:vga6448
   Snapshot date: 2025-12-08
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*/

==== Table of Contents ====

[[#vga6448_a_text-based_monochrome_vga_display|VGA6448, A Text-based Monochrome VGA display]]

[[#introduction|Introduction]]

[[#features|Features]]

[[#theory_of_operation|Theory of Operation]]

[[#design_files|Design Files]]

[[#software|Software]]

====== VGA6448, A Text-based Monochrome VGA display ======

===== Introduction =====

VGA6448 is initially discussed on 6502.org forum [[http://forum.6502.org/viewtopic.php?f=10&t=6502|here]]: It is a simple design suitable as a piggy-back board for system RAM to add VGA capability.

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=d3d488&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/crc65/vga64/vga6448_banner.jpg|{{https://retrobrewcomputers.org/lib/exe/fetch.php?w=600&h=333&tok=e3f7e4&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fbuilderpages%2Fplasmo%2Fcrc65%2Fvga64%2Fvga6448_banner.jpg?600x333|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_crc65_vga64_vga6448_banner.jpg}}]]

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=56e301&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/crc65/vga64/dsc_64730222.jpg|{{https://retrobrewcomputers.org/lib/exe/fetch.php?w=500&h=352&tok=0497eb&media=https%3A%2F%2Fwww.retrobrewcomputers.org%2Flib%2Fplugins%2Fckgedit%2Ffckeditor%2Fuserfiles%2Fimage%2Fbuilderpages%2Fplasmo%2Fcrc65%2Fvga64%2Fdsc_64730222.jpg?500x352|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_crc65_vga64_dsc_64730222.jpg}}]]

===== Features =====

EPM7064S or ATF1504AS CPLD

4K dual port RAM

25.175MHz clock

===== Theory of Operation =====

===== Design Files =====

Schematic

CPLD design

==== Software ====

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:crc65:vga64:matrix_working.zip|Matrix screen saver]]. The program starts at $a000