{"id":329,"date":"2019-12-03T07:30:14","date_gmt":"2019-12-03T03:30:14","guid":{"rendered":"http:\/\/www.jrtwine.com\/blog\/?p=329"},"modified":"2019-12-03T07:31:05","modified_gmt":"2019-12-03T03:31:05","slug":"galaga-bosconian-ram-tip","status":"publish","type":"post","link":"https:\/\/jrtwine.com\/blog\/galaga-bosconian-ram-tip\/","title":{"rendered":"Galaga\/Bosconian RAM Tip"},"content":{"rendered":"

Galaga uses 4-bit<\/strong> RAMs.\u00a0 This means that in order to handle 8-bit data, it needs to group RAMs in sets of 2 – one for the lower 4 bits, and the other for the higher 4 bits.\u00a0 When Galaga detects a RAM error during the self-test, it does not show the location<\/em> of the failed RAM, they shows which<\/em> RAM failed.<\/p>\n

For example, if the chip handing the higher <\/i>bits in RAM “bank” 3 fails the self-test, it will show RAM 3H<\/code><\/strong> and likewise if the chip handling the lower<\/em> bits fails, it will show RAM 3L<\/code><\/strong>.\u00a0 These may look like locations on the board somewhere, and this tends to trip some people up as they go looking for RAM chips at 3H<\/code><\/strong>\/3L<\/code><\/strong> on the board.\u00a0 Instead, here are the locations the different RAM errors refer to (on Galaga, all RAM errors point to the Video board):<\/p>\n

RAM 0L<\/code> – RAM at location 1K<\/code> has failed
\nRAM 0H<\/code> – RAM at location 1K<\/code> has failed
\nRAM 1L<\/code> – RAM at location 1K<\/code> has failed
\nRAM 1H<\/code> – RAM at location 1K<\/code> has failed
\nRAM 2L<\/code> – RAM at location 3E<\/code> has failed
\nRAM 2H<\/code> – RAM at location 3F<\/code> has failed
\nRAM 3L<\/code> – RAM at location 3K<\/code> has failed
\nRAM 3H<\/code> – RAM at location 3L<\/code> has failed
\nRAM 4L<\/code> – RAM at location 3H<\/code> has failed
\nRAM 4H<\/code> – RAM at location 3J<\/code> has failed<\/p>\n

Bosconian also shows H\/L RAM errors that need to be mapped to RAM locations:<\/p>\n

RAM 1L<\/code> – RAM at location 2N<\/code> on CPU board has failed
\nRAM 1H<\/code> – RAM at location 2N<\/code> on CPU board has failed
\nRAM 2L<\/code> – RAM at location 2N<\/code> on CPU board has failed
\nRAM 2H<\/code> – RAM at location 2N<\/code> on CPU board has failed
\nRAM 3L<\/code> – RAM at location 1E<\/code> on Video board has failed
\nRAM 3H<\/code> – RAM at location 1E<\/code> on Video board has failed
\nRAM 4L<\/code> – RAM at location 1E<\/code> on Video board has failed
\nRAM 4H<\/code> – RAM at location 1E<\/code> on Video board has failed
\nRAM 5L<\/code> – RAM at location 1H<\/code> on Video board has failed
\nRAM 5H<\/code> – RAM at location 1H<\/code> on Video board has failed
\nRAM 6L<\/code> – RAM at location 1H<\/code> on Video board has failed
\nRAM 6H<\/code> – RAM at location 1H<\/code> on Video board has failed<\/p>\n","protected":false},"excerpt":{"rendered":"

Galaga uses 4-bit RAMs.\u00a0 This means that in order to handle 8-bit data, it needs to group RAMs in sets of 2 – one for the lower 4 bits, and the other for the higher 4 bits.\u00a0 When Galaga detects a RAM error during the self-test, it does not show the location of the failed […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,10],"tags":[],"class_list":["post-329","post","type-post","status-publish","format-standard","hentry","category-repair-logs","category-ballymidway"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t