Hey everyone. Have you ever wondered how we handled tape protection systems back in the day? well... wonder no further as I've created a rather length tutorial covering Speedlock 1987 used on the Dizzy Cassette for the Amstrad CPC.
You will need some assembler knowledge, and I've created a video to go with the tutorial.
would be great to get your feedback if anyone has the time to read all the way through.
I've included a .DSK image with the assembler files used in the tutorial, and assembler listings on my GitHub for CPC related code etc.
All hopefully explained in the blog entry.

Today’s entry isn’t about how cool this game was and still is today, but a flaw with the Disk Protection System used. DiscSys : DiscSys was a fairly popular Disk Copy Protection mechanism in use during the 80s Amstrad CPC, essentially it worked by created Invalid Track Data that could not be copied without using specialist tools/software. 

Amstrad and ZX Spectrum DSK Tool : I was looking at some potential differences between retro machine emulation and physical hardware. Emulation has come on a very long way since the first versions rolled out the door in the early 90s. The expertise within the retro community is incredible, the internet has only accelerated the sharing of ideas, tools, modern hardware interfacing to legacy kit to anyone with a connection. [...]

µPD765A Disc Controller – Primer : [...] A friend back then “Dave” had access to all sorts of hardware documentation. One morning on his way to work, he dropped off a bundle of documents including hardware/circuit diagrams for the Amstrad CPC computer range, service documents and the µPD765A specification. Stuff I couldn’t get hold of myself.

I set to work reading the documentation, learning about Microelectronics at school helped enormously. From about the age 10, I was no stranger to a soldering iron and PCBs. The article below is the result of my own work back in the late 80s, using code from my original three inch disks. [...]

url/src: https://muckypaws.com/2024/02/21/amstra ... -dsk-tool/

Diagnostic Command is it Bugged? : [...] Back in the later 80’s, using my knowledge of the FDC Controller in my previous blog entry I created a disk protection system, called “JaceLock”, I will go into the details of this in a future entry. The reason the disk couldn’t be copied by commercial copiers was related to a potential Bug in the disk controller implementation. [...][/b]

Let’s Hack… Fly Spy! : In the early days of Hacking, it was rare a protection system would be as memorable as the one created by Richard Aplin, Author of Fly Spy published by Mastertronic. Havking was always a trade of ideas and new techniques. In this post I’ll cover off how to transfer FlySpy to disk that you can follow along.