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From: Phill Harvey-Smith [mailto:afra@aurigae.demon.co.uk]

Browse Source 
Sent: Saturday, October 11, 2008 12:01 PM
To: submit@mamedev.org
Subject: 6821 PIA changes

Hi,

Can this change be added to the 6821 pia code, it adds a function that 
allows the client code to get the status of CA2, taking account of the 
internal pull up resistor. This code only adds a function and does not 
change any existing code so should not have any impact on existing
drivers.

This change is needed for a couple of the mess drivers.

Thanks.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
This commit is contained in:
Aaron Giles 2008-10-16 07:19:16 +00:00
parent 8769bea92e
commit 5bcb95dff7
2 changed files with 14 additions and 0 deletions
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13
src/emu/machine/6821pia.c
View File

@ -981,6 +981,19 @@ int pia_get_output_ca2(int which)
return p->out_ca2; return p->out_ca2;
} }
// Version of pia_get_output_ca2, which takes account of internal
// pullup resistor
int pia_get_output_ca2_z(int which)
{
pia6821 *p = &pias[which];
p->out_ca2_needs_pulled = FALSE;
// If it's an output, output the bit, if it's an input, it's
// pulled up
return p->out_ca2 |
C2_INPUT(p->ctl_a);
}
/************************************* /*************************************

1
src/emu/machine/6821pia.h
View File

@ -94,6 +94,7 @@ void pia_set_input_ca1(int which, int data);
int pia_get_input_ca2(int which); int pia_get_input_ca2(int which);
void pia_set_input_ca2(int which, int data); void pia_set_input_ca2(int which, int data);
int pia_get_output_ca2(int which); int pia_get_output_ca2(int which);
int pia_get_output_ca2_z(int which);