Microdrive data line format

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xelalex
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Re: Microdrive data line format

Post by xelalex »

@martyn_hill Sorry for the late reply. I've had a quick glance at your QLUB project. This looks really interesting! Once work on OqtaDrive gets more quiet, I'll try this out. It should be interesting to find out where there are similarities. And who knows, maybe somewhere down the line these two functionalities could live on the same micro-controller board.


Derek_Stewart
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Re: Microdrive data line format

Post by Derek_Stewart »

Hi

I bought an Arduino Nano, which I was going to build the interface to the QL external microdrive connector.

Do you have a sematic of the required setup?


Regards,

Derek
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xelalex
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Re: Microdrive data line format

Post by xelalex »

You'll find everything over at the project home, schematics and source code. Pre-built binaries for the daemon are available in the release section. You don't need a GitHub account to access this.


Derek_Stewart
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Re: Microdrive data line format

Post by Derek_Stewart »

xelalex wrote:You'll find everything over at the project home, schematics and source code. Pre-built binaries for the daemon are available in the release section. You don't need a GitHub account to access this.
Hi,

Sorry sbot the spelling mistake.

Thanks for the update, I did clone the Guthub files for oqtadrive, I forgot about the image the hand drawn circuit diagram, for connection to the QL or Spectrum.

I will do a prototype on vero-board and produce a proper circuit schematic in KiCad.


Regards,

Derek
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Bloodnok
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Re: Microdrive data line format

Post by Bloodnok »

xelalex wrote:I think gertk stopped working on this due to time constraints back then. According to the document history of the vDrive manuals (ZX & QL), they were first released in 2017. Not sure about the firmware lineage though, since it's closed source.
The vDrive was developed from early 2015 through to early 2017 with subsequent revisions over the following years(and continuing). The decode hardware was sorted very early on for the ZX. SD card file system support along with built-in firmware update capability quickly followed along with the development of the toolkit to make the vDrive a more usable standalone product rather than just a simple technical demonstration. I decided to produce a QL version sometime in 2016-this proved to be much more of a challenge. Finally in 2017, after several PCB revisions, and once the manuals and install guides had been done, I thought I'd make a couple for enthusiasts :-) As it turned out, I had significantly underestimated the demand and with the continued interest, I'm still making both the ZX and QL vDrives today (https://vretrodesign.com). I've lost count but estimate there have been over 1000 vDrives sold to date. Not bad for an obselete and much maligned technology!


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bwinkel67
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Re: Microdrive data line format

Post by bwinkel67 »

Bloodnok wrote:
xelalex wrote:Finally in 2017, after several PCB revisions, and once the manuals and install guides had been done, I thought I'd make a couple for enthusiasts :-) As it turned out, I had significantly underestimated the demand and with the continued interest, I'm still making both the ZX and QL vDrives today (https://vretrodesign.com). I've lost count but estimate there have been over 1000 vDrives sold to date. Not bad for an obselete and much maligned technology!

I love the vDrive. I've been doing a lot o coding on the QL lately, going back to the late 80's early 90's old-schools style as I finish my ZX81 ROM emulator. Once a week I sit there and make changes using Jan's QED and then compile and link, all through the vDrive. It's slow but has such nice pacing and I go and either watch TV or do other stuff. Really makes me think about my code changes, vs just doing a quick change, compile, run, crash, repeat that I might do if I'm running in fast emulation. This week I had to re-do my Windows machine from scratch and it was nice to sit there and do some code compiles on the QL with vDrivewhile my PC was in the rebuild.


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Bloodnok
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Re: Microdrive data line format

Post by Bloodnok »

Just tracking back over old posts, prompted by the recent interest in the Oqtadrive, and thought it useful to point out how much information was made available following on from Gertz's original investigations.
For example here's a post detailing the Microdrive encoding scheme way back in 2017: viewtopic.php?f=2&t=1187&start=100#p201
All the information required to make a Microdrive emulator has been freely and openly available for many years and with the advent of IOT related technology and development tools, the programming challenge has become almost trivial.
To design a miniature data recording system, running at insane tape speeds, costing pennies to produce, that actually worked; now that is real genius (https://en.wikipedia.org/wiki/Ben_Cheese).


kladogen
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Re: Microdrive data line format

Post by kladogen »

Hi,
I'm trying to port gertk's microdrive emulator to arduino nano + esp32. I intend to use the nano as the interface with the QL, since it supports 5V pins with enough current and use the ESP32 as an interface to the SD card and WiFi access - web server to upload MDV files and manage them.
Although I can read sectors from the QL while formating I can't send data to the QL. When I send sectors they just run through for ever and the QL does not respond - not even a not found message, until I manually stop the play.
It seems I'm missing something important but I just cant find it. I have managed perfect timing (using an oscilloscope = 5μs/5μς for 1, 10μs for low) and also I have checked the timing between header and data block. Also I have recorded the signal I'm sending and decoded it by hand so I checked that it is correct - the data read from the MDV file is actually sent to the tracks. I have tried to switch tracks, checked check sums and anything else I could think of but no luck.
Any ideas?


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M68008
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Re: Microdrive data line format

Post by M68008 »

kladogen wrote: Wed Dec 21, 2022 6:05 pm Any ideas?
Are you sending the long gap of zeros between sectors? ZX8302 should detect it and generate an interrupt for the CPU.


martyn_hill
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Re: Microdrive data line format

Post by martyn_hill »

Hi kladigen!

Just to follow-up Daniele's reply, the 'GAP' should in fact be a static level on each Data line - doesn't matter if logic high or low - but static until the Preamble that synchronises the PLL in the ZX8302 immediately ahead of the sector/block data.

If you could share here an image of the oscilloscope output, we could probably see what's up ...


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