67 lines
2.3 KiB
C++
67 lines
2.3 KiB
C++
/*
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epple2
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Copyright © 2019, Christopher Alan Mosher, Shelton, CT, USA. <cmosher01@gmail.com>
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This program 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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This program 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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef DISK2READWRITEHEAD_H
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#define DISK2READWRITEHEAD_H
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#include "movable.h"
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/**
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* @brief Disk ][ read/write head assembly
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*
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* Represents the read/write head assembly of a Disk ][ floppy drive.
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* The assembly includes a "sled" that can move back and forth, with a
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* read/write head attached to it. The sled is moved by the rotor from
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* the stepper motor.
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*
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* Rotation of the rotor will cause the sled to move back or forth, along
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* with the read/write head, positioning it over a "track" on the floppy disk.
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*
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* If the rotor attempts to move the sled too far, the sled will resist and
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* prevent the rotor from rotating.
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*/
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class Disk2ReadWriteHead : public Movable {
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public:
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virtual ~Disk2ReadWriteHead();
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int position() const;
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virtual bool move_by(int delta_position);
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private:
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/**
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* Total count of possible positions for this read/write head.
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*
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* A position will represent a track on a floppy disk.
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* The number of tracks really depends on the floppy disk.
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* The Disk ][ has a "stop" at track zero, but not at the high end,
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* so this is where it can vary from disk to disk.
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* Typical disks have 35 tracks, and allow quarter-track precision.
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*
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* In this emulator, we adhere to the WOZ v2 specification for floppy disks.
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* It allows for up to 40 tracks (with quarter-track precision):
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*
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* 0=t0, 1=t0.25, 2=t0.5, 3=t0.75, 4=t1, ... 140=t35.00 ... 159=t39.75
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*/
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const static int C_POSITION = 40*4;
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int current_position = C_POSITION/2; // random start
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};
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#endif // DISK2READWRITEHEAD_H
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