{"id":809,"date":"2026-05-21T04:13:28","date_gmt":"2026-05-21T00:13:28","guid":{"rendered":"https:\/\/www.jrtwine.com\/blog\/?p=809"},"modified":"2026-09-17T06:15:29","modified_gmt":"2026-09-17T06:15:29","slug":"ms-pac-man-with-no-sprites-ghosts-ms-pac-man","status":"publish","type":"post","link":"https:\/\/jrtwine.com\/blog\/ms-pac-man-with-no-sprites-ghosts-ms-pac-man\/","title":{"rendered":"Ms. Pac-Man with no “Sprites” (Ghosts, Ms. Pac-Man)"},"content":{"rendered":"\r\n

So, a gentleman reached out to me right before my fusion surgery asking me to have a look at his Ms. Pac-Man game. It was not showing sprites<\/em> but was otherwise behaving correctly – it passed self test, and you could still see dots being eaten during attract mode, etc.<\/p>\r\n


\"\"<\/a>\"\"<\/a><\/p>\r\n

Initial instinct was something wonky with the VRAM Addresser Board<\/em>, so I gave him a known good one and sacrificial socket to test with, but this produced no change. He dropped off the board and I gave him one of my spares so he would be able to at least play his game while I was in recovery.

When I was able, I took a closer look at the board and did not see anything obvious as far as lifted traces, bent pins, etc. I looked at all of the troubleshooting information and repair logs that I could find, including the Mowerman<\/em> docs, but none of the solutions for the same identical problem seem to apply here.

Using the troubleshooting guide for some theory of operation<\/em> info, I started working my way from the Attack RAMs<\/em> all the way to the video output. I eventually stumbled upon a 74LS161 @ 1E<\/strong> whose outputs were not following its inputs: they were essentially floating.

I piggybacked a replacement ‘161 on top of it:<\/p>\r\n

\"\"<\/a><\/p>\r\n

– and this\u00a0made the game draw the sprites correctly, so it was a simple matter of clipping the chip, desoldering its pins, putting in a socket, and sticking in the replacement ‘161.\u00a0 After that, I confirmed the sprites returned and were behaving correctly.<\/p>\r\n

\"\"<\/a><\/p>\r\n

Board repaired, and a new(?) solution for the “missing sprites” problem.<\/p>\r\n

\r\n

As it turned out, the board that I let him borrow happen to have the Doc Cutlip<\/em> cheat on it where you hold the one player start to become invincible and the two player start to go fast (or vice-versa?) and he liked it, so I planned to put that on his board before I gave it back to him.<\/p>\r\n

Originally I was going to erase and burn his existing<\/em> 2532 @ 6F<\/strong> that was already on his board.\u00a0 But even though it erased correctly, it would not program consistently and would fail verification at different (progressive) locations. I tried another erase\/burn cycle and got the same behavior so I binned<\/em> it and burned one from my stock and used it instead.\u00a0 (Working versions of these EPROMs are getting harder and harder to find without breaking the bank.)<\/p>\r\n","protected":false},"excerpt":{"rendered":"

So, a gentleman reached out to me right before my fusion surgery asking me to have a look at his Ms. Pac-Man game. It was not showing sprites but was otherwise behaving correctly – it passed self test, and you could still see dots being eaten during attract mode, etc. Initial instinct was something wonky […]<\/p>\n","protected":false},"author":2,"featured_media":815,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[20,33,132,131,21,26],"class_list":["post-809","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-arcade","tag-midway","tag-ms-pac-man","tag-pac-man","tag-repair","tag-repair-log"],"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