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(Topic ID: 222797)

NEW! Williams System 3-7 In-Game Test ROMs

By pincoder

2 years ago

Topic Stats

  • 241 posts
  • 34 Pinsiders participating
  • Latest reply 3 months ago by pincoder
  • Topic is favorited by 61 Pinsiders


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#3 2 years ago

Some of these look very handy. Great work. I am going to play with the sound test to explore the noises in each sound ROM. The CMOS clear is useful for a system 7 board running older software and NVRAM as switching between games leaves you no easy way to clear the RAM on the board.

Since there is sixteen 2716 images one could build a 27256 EPROM board with a 4 position dip and pullup resistors to bank switch between each test rom.

1 week later
#18 2 years ago
Quoted from stangbat:

I'd be interested in something like this. I want to try this out to play with it but having to locate and program 16 ROMs has kept me from doing so. I'm sure I have 16 laying around, but a lot of them have other test programs on them or are for specific games that I uses to test. I really don't want to erase them for this and then later have to do it all over again to use them for the same purpose they're being used for now.

The blank PCBs shouldnt be expensive to have made. Perhaps I can upload the gerber file to a site people can order from or just have some made the next time I order blank PCBs.
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The four upper most address bits are attached to a dip switch bank. When the dip switch bank is closed it is a zero, grounded. When dip switch bank is open it is pulled up by 10K sip resistor to make a one. That should split the 256K EPROM into sixteen 16K chunks.

2 weeks later
#23 2 years ago

27512 is the bggest in a dip28 package. With a five pin dip switch bank would give you 32 selectable ranges of 16K ROM.

I can create a shareable link on the place I normally order PCBs from but the minimum order is 10pcs for $40usd something shipped slow boat from China. Message me for the link. I could upload the gerber files somewhere or use another board house I can upload the files that other people can order from.

1 week later
#37 2 years ago

fun tip about the internal ram... i have found most motorola brand 6808s found in wms sys 6-7 gear will actually function as a 6802. If you have a board on a bench you can check it by flipping the internal ram jumper/pull resistor and a test rom. Occasionally you see one with a ram error or it acts up in game play, but 90%+ a MC6808 stuffed in WMS boards of the time functions as a 6802. Same thing shows up in Bally world too specially with the moto 6808s with bally's custom part number imprinted. Save a 6810 for something else if it is in a socket. AMI 6808s don't have the ram. Haven't really checked other brands.

#39 2 years ago
Quoted from pincoder:

Interesting. So even back then they were selling chips that didn’t make the cut as lower quality chips having limited features. Some things never change!

I have even seen evidence of a previous mc6802 mark rubbed off and 6808 put down on top of it with a date code 3 weeks later.

a lot of the WMS and Bally custom part numbered chips had a similar remarked from the factory look. Obvious abrasion marks where the imprint is.

2 weeks later
#42 2 years ago

you can check the suspect address pin at the eprom socket. When the dip is closed it should be low and when the dip switch is open the resistor pulls it up to 5v.

1 week later
#57 2 years ago

Good way to check for dead address / data buffers or a short is to take out everything but the CPU. The address and data lines all go active (cpu looks for program?). So in that state you can check on each side of the buffers.

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