Did you try with an unmodified EPROM to make sure it's not caused by one of the program modifications?

hap, you're right, I thought of that too. And I did, with another new EPROM, and everything worked (Version 2 of CE's connection, same as in the pictures).

Then I slightly modified my hack, like this:

..and burned it again on a new EPROM, and it worked, no more lost or added pieces in RAM. I can't explain codewise why it didn't work the first time, so I suspect a faulty EPROM.

Now testing if it really plays a better game..

After playing some games I can now confirm that my modified Delta-1 is playing Boris-style, as it (maybe) was intended 1979. It won both matches against Portachess II. Will do some more tests with Mini Chess, as Delta-1 didn't win any games of the 11 listed in the Aktivschach_Elo_Liste_2020.
The final hack-version here:

Angehängte Dateien

ccdelta1_hack.zip (3,7 KB, 66x aufgerufen)

Besides, this 'missing' table is in fact the starting position (high nibble) combined with a positional bonus for the evaluation (low nibble), I assume.

It shows up in every Boris version, and interestingly, Ron Nelson used this same scheme too, beginning with CC7 up to Voice Sensory. He changed it a little bit in the years. (See the hex comparison attached.)

So it would indeed be possible to get a different playing behaviour by modifying that table, as Tibono suggested.

Have a look here for more about these inards:
http://www.hiarcs.net/forums/viewtopic.php?t=9497

Miniaturansicht angehängter Grafiken

 

Well, if this version does indeed play better, then I could of course add it to CB-Emu, e.g. as 'Delta-1 (modified)'.

But before doing it, I'd have to know the correct address mapping:
Is it (as for the original ROM)
map(0x2000, 0x20ff).mirror(0x1f00).ram(); // A13
or (like 'hap' posted for your 1st hack)
map(0x2bc0, 0x2bff).rom().region("maincpu", 0x0880);
map(0x2c00, 0x2cff).ram();
(or again something else, since you've changed the ROM once more)?

Regards,
Franz

The MAME modification was to place the evaluation table at the right place without hacking the ROM. I didn't test it though.

The ROM hack is for the original hardware (or unmodified MAME driver).

Franz, what hap posted is fine, it will do the same thing.
(Just copy that 64-bytes-table from ROM 0880-08bf to RAM 2bc0-2bff.)
In the new eprom I put it at ECC0, but that will be 'mirrored' at 2XC0-2XFF..

The other bit in the first version I removed wasn't a computed goto as I thought, but would be used for the display and was correct (FE instead of FD).
But it isn't called at all, so doesn't hurt.

Aah, I think I'm understanding it now (your F8 assembly listing was Chinese for me. ).

So you have added an extra code to copy this table to a different address, and hap's MAME change just remaps this 'wrong' table address to the correct place.
But then hap's method and your ROM hack should have the same effect, right?
If yes, then changing the mem map in MAME should be the simpler method, because you won't need an extra ROM file!?

Correct!

I let Boris rev1, Boris Diplomat and my modified Delta-1 solve this simple problem:



Boris rev1: 55 s
Delta-1 mod.: 60 s
Delta-1 (original-ROM CB-Emu) : 84s
Boris Diplomat: 101 s

Could somebody with an original Delta-1 test this?