Z80 ERROR

Cause
The didn't receive a reply to command $01 from the  in time. The Z80 doesn't test SM1 ROM, its RAM nor the but if any of those components are bad, they can prevent the Z80 from being able to reply which will then cause the error.

Suggestions

 * Check Z80 power, reset and clock
 * Check Z80 work RAM
 * Check Z80 control lines
 * Check Z80 data bus at

MV1C
The MV1C board displays this error with no cart inserted since it has no SM1 ROM. This is normal.