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