Microdrive ‘n’ Through

Having purchased and fitted the excellent vDrive ZX to an old Microdrive case, I now had the question of how to connect my working Microdrive to the vDrive. I’d bought the Microdrives separately and neither came with a through connector. I had a look around and realised that I could fashion one from a standard rear edge connector. The pin pitch is the same standard 2.54mm.

I borrowed an original connector from my friend Russell to check if the connections are straight through (gender reversers connect opposite pins). I used a multi-meter on it’s ohms (resistance) range to check and all the connections are straight from one side to the other. With that confirmed, I set to work making my substitute adaptor.

Pulling Pins from the Edge Connector

Pulling Pins from the Edge Connector

I used the original through connector as a template and pulled out pins from the long edge connector I was going to cut up. I started with one set of pins at the end and worked my way along. The reason for this is that cutting through the pins is difficult, noisy and can send the hacksaw blade off course. The method of pin removal I use to do this is to use a pair of tweezers to push each pin towards the center line of the connector from behind and then hook the end of the tweezers under the loop of the pin to pull it out. Be very careful not to pull more than one pin out at a time.

Pins Pulled

Pins Pulled

Once I had pulled all the necessary pins out, I set to work cutting the connector up. I used a bench mounted vice to keep the connector steady whilst I cut. A clamp on a bench would have worked equally well.

First, I cut the end off using the barrier between the pin sections as a guide for the hacksaw. I cut it nice and slow and let the saw do the work. On the next cut, again I used the barrier as a guide to cut as close to the pin chamber as possible. This process left the thin wall of the barrier intact. Continuing, I cut off the excess from the next connector before finishing with the last cut to separate the second part of the through connector from the edge connector strip.

Connector Cutting Diagram

Connector Cutting Diagram

Both the cut pieces needed to be tided up. I used some ‘pound shop’ sand paper. I did this roughly at first because I knew I was going to sand them further once the connector was soldered together.

Sanding the Connectors

Sanding the Connectors

Two Connectors

Two Connectors

Now the connectors were ready for connecting together. To make the connectors line up, I put a very small bend on the pins at the rear of the connectors. On one connector, I bent the pins in and on the other, I bent the pins out. This only had to be fractional and is just to allow the connectors to join in parallel. If you don’t do this, the connectors will be offset by a small amount. Although in practice this doesn’t affect operation of the drives.

Slightly Bent Pins

Slightly Bent Pins

I fixed the two connectors together with a piece of insulation tape to keep the two connectors stable whilst I soldered the end connections together. I Made sure to line up both key gaps together. You would be surprised how easy it is to get one inverted (Almost caught me out). Once the end pins were done, I removed the tape to gain access to solder the rest of the connections. Again, a clamp or blue tack could be have been used instead.

Taped Connectors

Taped Connectors

I then carefully soldered the pins at either end of the connectors, being careful not to use too much solder. I then checked the connections with an eye glass to make sure they were good before I removed the tape and soldered the rest of the connections.

Soldering Finished

Soldering Finished

As you can see, I needed to give the ends a little more work. I gave the ends of the combined connectors another sanding and cleaned off the resulting dust. The last step was to add the key. I find it easy to use a bit of strip board for this purpose. It breaks readily and you only need a small bit to do the job. A strip of three holes width is adequate. Once I had the strip, I inserted it into the connector as far as it would go and snapped it off close to the connector as I could.

Snap-Off Keys

Snap-Off Keys

I usually secure the strip board slice with some glue to prevent it from falling out later on. Connecting the drives together is exactly the same as you would do if you used an original connector. The only difference being that the drives aren’t flush together and you can’t connect the underside plate for stability. I have found that, in use, this hasn’t mattered since the edge connectors are a tight fit.

Through Connector on First Drive

Through Connector on First Drive

Drives Together

Drives Together

As you can see from the image, the drives stand apart a little but this doesn’t affect the operation at all. I do use the connected drives on a flat surface though.

Hopefully, this is a useful stop-gap whilst I source my own original connector. Or perhaps the home made connector will serve me well enough to keep in use.

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vDrivin’

I was extremely lucky to secure one of the first vDrive ZXs when the creator, Charlie Ingley put them up for sale on Sellmyretro.com The sale came at just the right time, since I had just got my Interface One and one Microdrive working with the help of my good friend Russell. Taking his advice, I re-capped both the drives that I had but only one was operational. However, due to the pending release (at the time) of the vDrive ZX, this didn’t matter so much.

The package arrived from New Zealand in good time (about a week and a half). The contents were well packed and came with a note explaining where to get the information to install and use the device. The vDrive components that Charlie supplies are retro-fitted into an existing drive case.

vDrive ZX Kit of Parts

vDrive ZX Kit of Parts

The first step in installation is to strip the old drive down. Charlie’s instructions give clear guidelines with regard to this. Having re-capped the boards inside the non-working Microdrive, I had no trouble, once again, opening the Microdrive’s case and preparing it for a vDrive.

Once stripped down, there is a spacer supplied by Charlie to fit. This is very easy and just slips on top of a post near the front of the base.

Spacer Fitted

Spacer Fitted

Once the spacer is in place, the first part of the vDrive can be fitted above. This is secured by two pan-head (rounded) screws towards the rear of the case in the two spots the original board was secured to. I ensured the board was parallel with the case by first tightening up the first screw just before it bit, then secured the second screw before finally finishing the first screw off.

First Board Fitted

First Board Fitted

The second board, that holds the SD-Card, piggy-backs the first board by being plugged into the DuPont style header. The header is two pins too wide but it is easy to center the top board so as to have a pin spare either side which is how Charlie explains it in the installation instructions. It is pretty obvious since that centers the SD-Card board to the case too.

Top Board Fitted

Top Board Fitted

The next part of assembly I found a little finicky. Not for any reason other than the LED hole in my Microdrive case was a touch too small to receive the new LED. However, it was a simple case of enlarging the hole. I do recommend you try the fit before you make any changes to your case as there is a small tolerance, and you may find the LED fits without any modification being required at all.

Using a pair of sharp scissors, my trusty Dahle ones I have had for many years, I opened them up and using the pointier side, I VERY gently enlarged the LED hole. If you have this issue, it is essential that you just take a minute sliver of plastic out of the hole to prevent the LED from floating around and not being an adequate friction fit.

Pushing the LED home

Pushing the LED home

After starting the LED off by hand, I gently pushed it all the way home with a flat screwdriver, being careful not to push on the wires going into the LED.

Now to close the case. Being careful to give enough clearance to the LED wires for the top screw, I closed the case and used the supplied pair of flat Philips screws to fix the top to the bottom.

Securing the Top Screws

Securing the Top Screws

Lastly, for me, there was a single long screw to fit on the base. I flipped the case over and did so. In Charlie’s instructions, the plate that is normally used to secure two Microdrives together is removed before the installation begins. My case had a broken tab and therefore didn’t require removal of the plate.

Securing the Bottom Screw

Securing the Bottom Screw

That completed the assembly. Nice and simple with ‘No Dramas’. I have kept the internals of the Microdrive and the old screws in case I can further service it later on or use it as a parts donor to fix another drive.

vDrive ZX Installed

vDrive ZX Installed

Now to connect the vDrive to my Spectrum. I chose my trusty Samsung issue 4S to try it out. I slid the Interface One under the Spectrum’s case as is usual and then connected the vDrive in place of my Microdrive.

Firing the kit up, and pressing ‘Run’ crashed the machine. The lights on the vDrive did react, flashing red-green-red-green but afterwards, the Spectrum screen remained white with no cursor. I tried the setup with an alternative machine with the same results. I had a feeling I knew what was wrong so I got my other Samsung out of storage. This one I had refurbished including replacing a faulty Z80 chip with one from the excellent Retroleum. This machine worked perfectly with a ‘Toolkit installed OK, 0:1’ report given and a short audio confirmation pip. As I suspected, the issue was a faulty M1 line on the other machine’s Z80 (which will require replacing!). Charlie has already resolved this issue and it will be fixed in a future firmware update.

vDrive ZX In Use

vDrive ZX In Use

When you are preparing to use an SD-Card, you need to initialise it by typing .sdinit This is part of the toolkit on board the vDrive. The prompt ‘Format & initialise SD [Y/N] ?’ is given. Replying to this with a lower case ‘y’ currently reports ‘OK 0:1’ but actually does nothing. Replying with a Capital ‘Y’ using the Caps Shift key initialises the SD-Card correctly. I informed Charlie about this issue and he replied that he had included it as a feature to prevent mistakenly formatting a card. However, he feels it is redundant now and will remove it in a future firmware revision.

The initialisation automatically creates a single virtual Microdrive slot on the SD-Card. To this, you need to add an image. This is a two stage process. First you issue a .mkimg “filename” command which creates a .mdr file with your supplied filename. The next step is to allocate the slot with the image. This is carried out using the .ld drive “filename” command. Replace ‘drive’ with the virtual drive number you wish it to be. In our case, it will be ‘1’ since there is only one slot currently available. When you have done this, you can do a .ls to list the SD-Card contents and a .li to list your current drive.  Lastly, you will need to format the virtual drive for use. This can be done with the usual Spectrum FORMAT “m”;drive;”filename” command or Charlie’s rather shorter .f drive “filename”. Depending on the Interface ROM version you have, you will either end up with a 127K formatted virtual drive (ROM V1) or a 126K virtual drive (ROM v2). After formatting, a normal CAT drive will give you the name of the virtual drive and the capacity.

You can then use this virtual drive just like a normal Microdrive. All the standard Microdrive commands should work and, because the vDrive acts as a Microdrive emulator, the Interface one cannot tell the difference between a regular Microdrive and a vDrive ZX.

Another feature of the vDrive is that you can have multiple ‘banks’ of configured drives. This means that on the same SD-Card, you can have a bank specifically for programming, another for gaming etc. You can also use virtual drive images in multiple banks. So, if you have an image you always want to be in slot one, just allocate it each time you make a new bank and it will be there.

One of the things that did catch me out was when I came to make a further image and allocate it. I had made an image and I was trying to allocate it to drive two (you can have up to eight virtual drives in one bank). I hadn’t created another slot to allocate it too. Only the first one is created automatically. The remedy for this is to issue a .mkdrv num, num being the number of slots you wish to create. You can confirm they have been created with a further .lv command. After this, you can follow the process for allocating the new image to the new slot as documented above.

Charlie has created a fabulous replacement for the Microdrive in the vDrive. Although there are a few ‘gotchas’ to be aware of, I believe this comprehensive system will be very popular. It is really easy to use, once you have used it for a short while and gives limitless storage and great replacement for the original Microdrive Cartridges which are sadly showing their age.

One of the first things I did was to find my copy of the original Microdrive Demo Cartridge and use the excellent copier program to back up my current cartridges to SD-Card. Since the SD-Cards can be read and written to with a PC/Mac, I also did a further backup on my PC.

Many thanks to Charlie Ingley for creating this great piece of hardware and also for helping me out with my first steps in using it.

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Content is King

There is an oft quoted law that describes my situation. It shall remain un-named in case it offends anyone! However, when I say I was all geared up to post lots of info on this site and suddenly, things many and varied popped up, seemingly out of nowhere to occupy my time.

I have decided to post a few quick lines to assure anyone who has managed to find the site that there will be more ‘stuff’ here in the near future.

I can mention a few. I have designed an updated Composite Output PCB, details of which are on the Projects Page. The newer board simply adds a switch so that you can build all three options on to the board and see which one works best with your monitor/TV without any re-soldering. I haven’t had the new board fabricated but I’m willing to publish it since it’s a very small upgrade.

Spectrum Composite Video Mod v2.00

Spectrum Composite Video Mod v2.00

I have also designed Spectrum +3 Composite Output board which I have successfully taken to prototype. When attempting to try it out, I have found that my +3 has some other sort of video fault which prevents it from working correctly. More investigation requred.

Sticking with +3s; A long time ago (2002) I came across a design for an IDE interface for the +3e. I loved this idea, a Spectrum with a Hard Drive, even if this particular interface only gave you half the capacity of the drive. At the time, I was just getting into PCB design and with a dodgy version of Ares/Proteus, I designed a gosh-awful board covered in links (since I couldn’t produce a double-sided PCB at home). However, it worked! I was very chuffed with myself and sent the design, along with an internal version to Garry Lancaster who kindly published it for me. I included images of my interface captured with the then brand new Casio QV-10 Digital Camera! You can still download the original archive from the WOS page. Having gotten first into Eagle and recently KiCad, I have updated the design and Garry has once again published it on the same page.

8-Bit IDE Interface by Pera Putnik and Garry Lancaster

8-Bit IDE Interface by Pera Putnik and Garry Lancaster

So, there are a few things going on. Even more behind the scenes, all of which will appear in due course.

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Welcome

This site is a companion site to www.ProjectAVR.com At the time I started that site, my focus was Atmel AVRs (Now owned by Microchip) and associated technology. I am still very interested in AVRs and I will continue to use them but I have concentrated on Sinclair Spectrums more recently. this is mainly due to the impending release of the bare Sinclair Spectrum Next boards, of which I pledged to.

I have designed several Spectrum related projects, some of which I haven’t published yet, others which currently are on ProjectAVR. These will be moved in due course.

On this site, I hope to present my own designs for Spectrum associated hardware and also review others designs and software. I may also do the occasional news article about anything that catches my eye.

Welcome to ProjectSPECCY

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