Help with an Amiga & Arduino Project (Retro) 0 Any Amiga Fans could help? - Page 1
Forum section: electronics / projects

author: RobSmithDev
author_rank: Newbie
timestamp: March 16, 2018, 11:27:30 am
content: I've been running an open source project to read and write Amiga floppy disks from a PC inside of Windows using an Arduino to actually control the drive. I have a whole write up about it on my site (http://amiga.robsmithdev.co.uk) which will probably answer the what/why/how etc.The project is mostly there, I can read and write data to the disk fine, when writing a track, I read back the track to verify it and all appears fine, but on a real Amiga system, some tracks are reported to have checksum errors.I am sure its a very slight timing issue as it appears to be intermittent, so I'm asking for anyone that has an Amiga, an Arduino and a good oscilloscope/logic analyzer to help. I would really like an oscilloscope/logic analyzer trace/dump of a real disk (a single track) how it looks originally, and then again how it looks after being read in (which works OK) and then written back to a new disk.Sadly I can't afford a better oscilloscope than the old one mentioned in the write up, but this would help advance this project.A few comments: I don't want to change the micro-controller as I want this to be as accessible as possible and I have had some great responses from people so far. This project isn't about making money, its just for preservation and a bit of fun.

author: @rt
author_rank: Super Contributor
timestamp: March 17, 2018, 01:06:01 am
content: Not that it wasn’t appropriate to post here, but have you triedEAB (English Amiga Board)? Most Amiga enthusiasts just wantto play games, and have someone else fix it when it breaks,but if the requirement is only an Amiga with floppy disk drive,and fast scope, then a few members there might fit the bill.

author: daybyter
author_rank: Frequent Contributor
timestamp: March 17, 2018, 06:53:17 am
content: I just wonder if one of those 6,- USB logic analyzers would work for you?

author: RobSmithDev
author_rank: Newbie
timestamp: March 18, 2018, 08:33:08 pm
content: just seen how cheap these can be, and for the rate I require it can be a cheap one, cheers

author: Fungus
author_rank: Super Contributor
timestamp: March 19, 2018, 07:44:06 am
content: Quote from: daybyter on March 17, 2018, 06:53:17 amNah, they won't show you the quality of the signal or exact timing.

author: BrianHG
author_rank: Super Contributor
timestamp: March 20, 2018, 06:27:22 am
content: Good luck in replicating the Amiga's Paula chip's serial IO of the disk read and write data port. It is married to a perfect division of the 28.63636 Mhz for north American version and 28.37516 Mhz for the European version. It is such a finicky tuned system that whenever you used the Amiga IBM dos floppy emulator, the IBM dos disks wouldn't always work right on a PC, or many read retries was to be expected. Writing was a dance of possible corruption of your PC disk. Even worse, many video games took advantage of the Paula's programmable timing oddities to create unusual tracks which could not be replicated by mere copying as a means of copy protection of the game.

author: RobSmithDev
author_rank: Newbie
timestamp: March 28, 2018, 09:52:27 am
content: Just to let you all know the issue is solved! - Didn't need a logic analyser in the end, turned out to be I wasn't writing enough data to clear out the previous data so the reader was getting confused when it found part-sector information left over. I now run an erase cycle first on the track and the problem disappeared! Reading and writing AmigaDOS disks is now more or less 100% successful from an Ardunio and PC. Now onto copy protected disks lol (I guess I'm going to have fairly limited success with this)

author: BrianHG
author_rank: Super Contributor
timestamp: March 28, 2018, 10:32:59 am
content: Quote from: RobSmithDev on March 28, 2018, 09:52:27 amDon't forget support for half step size tracking (Trick on manipulating the 8520's step and direction signal) and negative tracks and extra tracks...