The document provides an overview of floppy disk emulation for Apple II systems, detailing the technologies and devices involved, including various protocols and emulator options. Key topics include the evolution of Apple II floppy disk drives, the interaction of devices through different ports, and related software. Additionally, it references multiple external resources for further exploration of these emulation concepts.

1. Floppy Disk Emulation
Explained by Example
By Alex Lukacz

2. Apple II Mass Storage Devices
• Disk II Port - Disk II protocol
• Semi-Virtual Diskette (SVD) http://www.thesvd.com/
• bootZero http://www.bootzero.com/HDDD_A2_v1.2/HDDD_A2v1.2.html
• SDISK II - DISK II emulator for APPLE II http://tulip-house.ddo.jp/digital/SDISK2/english.html
• http://tulip-house.ddo.jp/digital/SDISK2V1/english.html
• USB AII-SPI-DSK http://maclcd.blogspot.com.au/search/label/Disk%20%5D%5B
• CHED http://lukazi.blogspot.com.au/search?q=ched
• Disk II Port - Smartport protocol
• Apple //c Smartport Compact Flash Adapter http://www.users.on.net/~rjustice/SmartportCFA/SmartportCFA.htm
• Smartport Virtual Hard Drive (SPVHD) http://www.spvhd.org/
• Apple II Slot - Floppy Drive (Replaces the floppy drive controller as well as the drive unit)
• Double Action Pseudo Disk / PseudoDisk2 http://alexfreed.com/FPGApple/pseudodisk.html
• http://www.applelogic.org/PseudoDisk2.html
• iDisk https://sites.google.com/site/idiskapple2/home
• Apple II Slot - Hard Disk Drive (Replaces the floppy drive controller as well as the drive unit)
• Apple II IDE/ATA interface http://s.guillard.free.fr/Apple2IDE/Apple2IDE.htm
• CFFA / CFFA3000 (inludes floppy emulation) http://dreher.net/?s=projects/CFforAppleII&c=projects/CFforAppleII/main.php
• Microdrive IDE controller http://www.reactivemicro.com/
• Focus IDE HD Controller http://16sector.com/
• Serial port
• Apple Disk Transfer ProDOS (ADTPro) http://adtpro.sourceforge.net/
• Pocket Serial Host http://osgeld.a2hq.com/category/projects/pocket-serial-host/
• Speaker port
• Online Apple II Disk Server http://asciiexpress.net/diskserver/
• Cassette tapes using a music payer (PC/iPad etc). Source data from Brutal Deluxe Software http://www.brutaldeluxe.fr/projects/cassettes/index.html
• Joystick Port
• Apple //t http://atomsandelectrons.com/blog/2010/04/apple-t/

3. Three generations of Apple II floppy
disk drives.
• 1. 5.25 inch floppy disk.
• 2. Smartport.
• 3. 3.5 inch floppy disk.
• Apple II Models and the generation disk technology they support :-
• II 1
• II+ 1
• IIe 1
• IIc 1
• IIe with Liron or Superdrive card 1, 2
• IIc with ROM 0 or later 1, 2
• IIGS 1, 2, 3
• IIc+ 1, 2, 3

4. Fundamentals

5. Bitstream
• Sync Bytes – 10bits 1111111100 – 4 in a
row.
11111111, 00111111, 11001111, 11110011, 11111100
• Encoding – 1 bit must be high, only 1 pair
of consecutive zero bits. 256 bytes of data
translates to 342 bytes.
• Counters to keep track of Tracks and
Sectors.

6. Track Structure

7. Emulation

8. CHED (Combined Hardware Emulated Drives)

9. Timing

10. Debugging (Signals)

11. Debugging (Data)

12. CHED2?

13. Reference
• Disk II
• Chapter 9 of "Understanding the Apple IIe" by Jim Sather
• Chapter 3 of "Beneath Apple DOS (Fifth Printing)" by Don Worth and Pieter Lechner
• Smartport
• Apple IIGS Firmware Reference ISBN 0-201-17744-7 – Chapter 7
• Apple IIc Technical Reference Manual ISBN 0-201-17752-8 – Appendix I Firmware
listings – Protocol Converter
• Apple Smartport technical note – smartport packet
• Inside the Apple II - Chapter 9
• Beneath Apple Dos

14. Smartport and 3.5 inch Drive
Support
• Smartport uses packets and WRPROT
line for ACK, PH0 for REQ hand shaking.
• 3.5 inch Drive ?

15. Thanks. Hack away and have fun.