Sinclair ZX80 / ZX81 / Z88 Forums

Can some one tell me how to verify the working of a multi-face 1 please

i sorted out the connections , but apparently nothing works ( no menu on the screen after pressing the nmi button )

Is the /NMI signal getting to the Z80?

Is the multiface paging out the BASIC ROM and enabling it's own EPROM?

Mark

Hi , Mark ,


its definitely not its own rom , i see the standard logon screen on the speccy

should it replace the standard logon screen with the colorfull option screen ??
this screen is NOT visible !!


only speccy and right arrow from opus 2.31



remember i am working on the butchered "thing" with the opus discovery in the pc-case

i already found the meaning of the 4 wires hanging out , it is J1 and the nmi switch ( j2 is left open ) , will investigate later this evening

is there a chance multiface and opus firmware clash with eachother ??

should it replace the standard logon screen with the colorfull option screen ??

With the multiface the standard boot screen will be displayed and the menu screen should be displayed after you press the button.

mmm , not working at all .

closed J2 to enable the multiface , J1 left open to disable the kempston .
but after clicking the button speccy reboots .

so no colorfull screen visible .

@1024mak ,

pressing nmi results in a speccy reset .

hope you can give me some hints .

all ttl logic has been tested and is ok .

eprom has already been changed for a new one , same result .

Either by design or by mistake, the NMI handler in the BASIC ROM will result in the Z80 jumping to the reset vector. With a MF1, it should switch out the BASIC ROM (forcing /ROMCS high) and page in its own ROM. Hence during the NMI it's the MF1 ROM that should be in control.

Mark

it will keep the speccy's rom , not switching to mf1 .

i am a bit out of options i fear .

And as some mooro..... has soldered everything together it is almost impossible to remove the mf1 board ( without damaging it ) .

might the ram be a possible deal-breaker here ?

I'm guessing, but I would have thought that if the RAM was faulty, you would get different symptons.

Is it really permanently soldered to the Speccy That makes it awkward...

Have you checked for solder splashes and short circuits? Also open circuit / bad connection issues?

This site has some technical details that may help.

Mark

some pictures of the disaster area ;
everything soldered together , no history known .

2 problems ,

no working multi face 1
opus error 9 ( has 2 eproms , 2.1 2.31 )