/* Imported from Wayback Machine
   Original URL : https://retrobrewcomputers.org/doku.php?id=builderpages:plasmo:vgaxram:2-boards:with-ps2
   Snapshot date: 2024-12-07
   Generator    : wayback-archiver
*/

====== VGA Expansion for 128KB RAM, 2-board stack (with PS2 interface) ======

This link to [[builderpages:plasmo:vgaxram:2-boards:no-ps2|2-board stack without PS2 interface]]

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=99a7a1&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/vgaxram/2-boards/dsc_70220827.jpg|{{https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/vgaxram/2-boards/dsc_70220827.jpg?600x504|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_vgaxram_2-boards_dsc_70220827.jpg}}]]

[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=59e7a8&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/vgaxram/2-boards/dsc_70230827.jpg|{{https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/builderpages/plasmo/vgaxram/2-boards/dsc_70230827.jpg?600x562|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_vgaxram_2-boards_dsc_70230827.jpg}}]]

===== Features =====

Plug in existing 128KB RAM socket

25.175MHz pixel clock, 60Hz VGA

4K dual port RAM for video memory and font lookup tables

64-macrocell CPLD, EPM7064SLC44

64 columns, 48 rows of 8×8 pixel monochrome text

Video RAM can be written any time

PS2 keyboard interface

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

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:vgaxram:2-boards:rambase_r1_scm.pdf|Schematic]] of RAM base board with PS2 CPLD

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:vgaxram:2-boards:vgaxram_r1_scm.pdf|Schematic]] of dual-port VGA board

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:vgaxram:2-boards:rambase_r1_gerber.zip|Gerber photoplots]] of RAM base board with PS2 CPLD

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=builderpages:plasmo:vgaxram:2-boards:vgaxramr1_gerber.zip|Gerber photoplots]] of dual-port VGA board