pi1541/Pi1541.cpp

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2018-05-20 04:53:34 +00:00
// Pi1541 - A Commodore 1541 disk drive emulator
// Copyright(C) 2018 Stephen White
//
// This file is part of Pi1541.
//
// Pi1541 is free software : you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Pi1541 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Pi1541. If not, see <http://www.gnu.org/licenses/>.
#include "Pi1541.h"
#include "debug.h"
Pi1541::Pi1541()
{
VIA[0].ConnectIRQ(&m6502.IRQ);
VIA[1].ConnectIRQ(&m6502.IRQ);
}
void Pi1541::Initialise()
{
VIA[0].ConnectIRQ(&m6502.IRQ);
VIA[1].ConnectIRQ(&m6502.IRQ);
}
//void Pi1541::ConfigureOfExtraRAM(bool extraRAM)
//{
// if (extraRAM)
// m6502.SetBusFunctions(this, Read6502ExtraRAM, Write6502ExtraRAM);
// else
// m6502.SetBusFunctions(this, Read6502, Write6502);
//}
void Pi1541::Update()
{
if (drive.Update())
{
//This pin sets the overflow flag on a negative transition from TTL one to TTL zero.
// SO is sampled at the trailing edge of P1, the cpu V flag is updated at next P1.
m6502.SO();
}
VIA[1].Execute();
VIA[0].Execute();
}
void Pi1541::Reset()
{
IOPort* VIABortB;
// Must reset the VIAs first as the devices will initialise inputs (eg CA1 ports etc)
// - VIAs will reset the inputs to a default value
// - devices will then set the inputs
// - could cause a IR_CXX IRQ
// - possibilities
// - reset while an ATN
// - reset while !BYTE SYNC
// - should be fine as VIA's functionControlRegister is reset to 0 and IRQs will be turned off
VIA[0].Reset();
VIA[1].Reset();
drive.Reset();
IEC_Bus::Reset();
// On a real drive the outputs look like they are being pulled high (when set to inputs) (Taking an input from the front end of an inverter)
VIABortB = VIA[0].GetPortB();
VIABortB->SetInput(VIAPORTPINS_DATAOUT, true);
VIABortB->SetInput(VIAPORTPINS_CLOCKOUT, true);
VIABortB->SetInput(VIAPORTPINS_ATNAOUT, true);
}