Defender and Fluke 9010a

KazooBR

Well-known member

Donor 3 years: 2023-2025
Joined
Jun 9, 2010
Messages
1,888
Reaction score
1,555
Location
Kalamazoo, Michigan
I've been working on a couple Defender boards and wanted to use my FlukeEmu and 6809 pod to verify ROMs in circuit. Took a while to sort through the bank switching, especially since Defender is different from other Williams boards related to banking ROMs.

The address to write to is D000 (not C900 like other boards). This is a ROM location so the data actually gets latched elsewhere and you cannot read it back to confirm. You write either 01, 02, 03 or 07 depending on which ROM pairs you want put into address space C000-C7FF and C800-CFFF. Then you can verify those pairs with commands like "ROM C000-C7FF SIG 16B9" and "ROM C800-CFFF SIG 4404" (for the first pair of ROMs, red or white/redline labeled version). Write 02 to D000 to get the next pair, etc.

I do have watchdog circuit pad cut but not sure if that's required.

Thanks to @braedel for reminding me of the Sean Riddle documentation.

Hope this helps somebody down the line.
 
It's all in the MAME driver:
Code:
void defender_state::main_map(address_map &map)
{
    map(0x0000, 0xbfff).ram().share("videoram");
    map(0xc000, 0xcfff).m(m_bankc000, FUNC(address_map_bank_device::amap8));
    map(0xd000, 0xdfff).w(FUNC(defender_state::bank_select_w));
    map(0xd000, 0xffff).rom();
}
 
Back
Top Bottom