symbiface 2 rom switches

[Munchausen]

Please take a photo of the pcb on both sides.
I'll think if there is a way I can write a test that can show it up.

Perhaps your CPC also shows the bus value strangeness that @SyX reported?

Do you have a link to where this is mentioned? I don't know about this...

[arnoldemu]

Do you have a link to where this is mentioned? I don't know about this...

CPC bus tests

[arnoldemu]

Symbiface 2 ram seems to be dk'tronics compatible including c1 and c3 but I expect only on 6128. I tested c0-ff. I didn't test on 464.

[arnoldemu]

something weird with fd11 or it could be my test 

ld bc,&fd11
in a,(c)

doesn't always work.

[arnoldemu]

symbiface 2 decodes upper 8-bits of rom select i/o port. So it's looking for dfxx.
symbiface 2 decodes upper 8-bits of ram select i/o port. It's looking for 7fxx.

other h/w does a partial decode.

the fd11 bug seems to be related to j2 on the pcb. edit: yes, if j2 is not connected the bug appears. with j2 connected the bug doesn't appear.

j2 does enable 8-31.
switches on board enable 0-7.
symbiface can override rom 7 on those cpcs where it will work.

[arnoldemu]

Symbiface 2 doesn't work correctly with 464/464Plus. '3' (c3,cb etc) configuration is not correct. All others are correct.
A15 is not forced like it is on dk'tronics expansions.

it works as gerald described to me.

C3 shows: 1,2,3,8

(1,2,3,4 are main ram, 5,6,7,9 are from first 64kb ram).

&c000 is not mapped to &4000. In 6128 and 6128plus this is done by the PAL inside the computer. and the external ram overrides &c000-&ffff.