SpritesMind.Net

Here's the completed schematic traced from my 1MB/8Mb DRAM Daughterboard... http://members.iinet.net.au/~msmcdoug/consoles/SMD_DRAM_schematic.pdf I used Charles' signal naming convention on the connector, except for the previously unknown control signals. The connector signals appear compatible with...

I know it would be really boring and time consuming, but is there any chance you could map the connections between the unknown eight DRAM signals from the connector (DCA-DCH) to the DRAM OE,WE inputs? I assume DA9 is not used because the DRAMs only need an 8-bit column and row? If we had that infor...

Still wading through the disassembly. I'd estimate 85% complete now. It's all the difficult and boring bits left - FAT filesystem routines - which aren't very nice in Z80 assembler. But since I'm so close to done I want to finish for completeness... :cry: I won't bother posting any more updates sinc...

KanedaFr wrote:for info, got a 3.1g bios which support (at least) 16M

BTW I assume you know 16M is 16Mbits or 2MBytes.

Looks like the larger memory boards require a MUX on the daughterboard. Which is why Charles' schematic differs from mine. Would be nice to build a replacement using SRAM...

very bad news.... :( perhaps the SMD got some short or strange data error and so bug on everything ? (in fact, I REALLY hope it's the reason!) time to find a way to clean the acid.... There are other parts of the circuit near the battery that may be affected by the corrosion. You need to check the ...

Thanks for the bug report, I'll fix it. Cut and paste error. :D Not your bug - it's on original PCB!!! Is the reset input instead connected to the MRES# or VRES# signals from the Genesis cartridge port? (well probably MRES# would make sense) I'll have to trace it... Is there any kind of limitation ...

A few interesting observations... My board is designated SMD 94V-0 yet it differs from both the schematic and the photo in this thread. I don't have the RC reset circuit (D2,R13,C23) next to the xtal. Not even the traces/pads on the PCB. (And FWIW there's two R13's on the circuit). When I 'fixed' my...

tcdev wrote:

KanedaFr wrote:I'll set up my Genesis here without the DRAM and see what happens...

Yes, I can run a cart without the DRAM installed.

2 choices: 1/ even when running an IC Cart, the SMD loads the game in DRAM then launch it => it will explain why I doesn't work (w/ DRAM but faulty lines or w/o DRAM) 2/ when running IC Cart, it only acts like a pass-throught => DRAM isn't the problem so I have something else.... tcdev, something a...

The 10-bit disk drive address inputs are hardwired to 3F0-3F7, where address bits 2,1,0 come from Z80 A2, Z80 A1, but SA0 is from the EPLD. It could let SA0 follow Z80 A0, but it gets A4-A1 as inputs along with higher address lines. So in other words, expect bit 0 of the register address to be weir...

the battery was removed years ago so it's not it...unless the acid it released years ago had slowly killed my smd... Unfortunately, the erosion of tracks damaged by battery acid will continue after the battery is removed, even more-so when the circuit is powered. There are articles on the net which...

The law of diminishing returns... :( Probably more than 80% complete. The remaining routines are, I believe, mostly concerned with FAT file system implementation. I'll be damned if I can work out HTF the cartridge-detect routine is supposed to work?!? Also, one or two funnies in the disk routines......

Charles, I believe you have the DRAM/cartridge size memory variables swapped in your document?!? Should be:

$DFF0 - DRAM size
$DFF1 - cartridge size

Also, the controller is read via port $DC

Working my way through the menu processing atm...

Probably done 65-70% of the code now.

OK, I've done at least 50% of the disassembly now. Noticed something weird that I need to confirm. In one of the routines, it appears to check for a 32-byte signature on track 80. If it is missing, it prints "UNKNOW DISK" (sic). If this is indeed the case, it might explain why I haven't been able to...

If not, it must be a custom FDC. Speaking of which, has anyone taken one apart to see what controller is in this thing? It's a Motorola MCS3201 FDC controller. I have the datasheet. The only confusion is the address mapping for the registers - they're not at "expected" addresses. I've already comme...