MattInX's Miscellaneous Musings Say what now?


The JVC 26-pin Interface – Part 3

Ok - so I should probably have written this post in May last year when it was all still fresh in my memory, except I never seemed to have time, then I forgot all about it, so here we are. In the intervening time, I've had a couple of folk contact me - some asking about progress because they too have these drives and are looking at either reading the disk or replacing it, but I also had a note from Oleksandr Kapitanenko over at PortaOne recommending DREM, which is a device that I was aware of thanks to the TRS-80 Trash Talk podcast. Apparently in the time between me originally looking at the device and the time I started posting on the subject, they've added support for the 26-pin bus. So if you're one of those people who have a system with this interface and a dead disk - that might be a solution for replacing the drive and I highly recommend getting in touch with them. I'm still interested in digging into the V86P's specific setup, so there will be more posts on the subject coming up.

If you've not read the previous posts recently, here's a quick recap of where I'd got to (and partly for my own benefit to wake up the appropriate neurons): I'd reverse engineered the interface to the point where I could confirm the pinout and signalling; I'd identified /SERVO_GATE was a sector index pulse; I'd identified the configuration from the datasheet indicating the on-disk layout of a sector; I'd been able to dump a sector with its ECC data via DOS; I'd confirmed the controller is using 2,7RLL encoding; and I'd successfully identified the start of the sector pre-amble and sector marker. This post is going to try and get written down what I did in the month following that last post.


Heating things up a bit

One problem owners of newer houses may be familiar with is the poor insulation of the room over the garage. The cheapest solution is to just put in batted insulation and vapour barrier (basically just plastic sheeting), which ought to be sufficient, but clearly isn't. The end result is the bedroom over the garage is often cold in the winter (and hot in the summer) - it doesn't help that the HVAC run to this room is probably one of the longest, and as builders also don't seem to tape their joints, likely to be subject to a lot of losses along the way. I could probably do a whole post just on things our builder has (or typically hasn't) done to save costs. However, this post documents a little project to help keep the chill out of our daughter's bedroom.