Recovering a slightly broken Vocore

OK, I managed to mess up the network settings on my Vocore. Oh well, it happens. It's not too bad... the device was still booting up and running... but was not accessible by Wi-Fi or by plugging in a network cable. So it's back to a good old serial connection. This is what I have done:

I've used a USB to Serial 3.3v TTL cable that I already had, and then just poked some jumper wires into the right places. Surprisingly it seems good enough. Anyway, in case I need to do this again, I thought that it would be worth taking a photo. I'm using PuTTY on a Windows box as the terminal. The settings I'm using are:

  • Speed: 57600
  • Data bits: 8
  • Stop bits: 1
  • Parity: None
  • Flow control: XON/XOFF

I connected the USB-to-serial cable first, then opened the connection using PuTTY. You then have a blank terminal screen. Then I connect the power to the Vocore, and you get to see all the logging information as the device boots. After a couple of minutes I press enter in the terminal and end up with the usual OpenWrt startup screen. After that you can use the console like normal. Anyway, it's handy to have that written down somewhere, because I'll probably break it again at some point. But I can report that I was able to fix the network config and things are back to normal now. Phew.

PDP-11/53: Floppy Cable

So it appears that I've forgotten how to connect up a floppy drive. In my defence, I have not used a floppy disk in years... Fortunately it seems that the cable in my PDP-11/53 should be the standard type.  My likely mistake was to rummage in my bin of "reclaimed" computer parts and try to use the cable I found in there. It does not have a twist in it :-( Typical.

Seriously. That might be the cause (or one of the causes) of the "Drive Error" message I was getting.  Mind you, if my RAM chips have died (as I suspect) then I might get other error messages. I should expect dodgy memory to manifest itself in all kinds of ways I guess.

So after some reading on the interweb I have been reminded that the standard floppy cable has a twist in it.  It looks hacky; but was the normal technique used to distinguish drive A: from the B: drive. Of course the cable I had in my box of leftovers was flat - a non-standard cable.  I expect that it won't work in my PDP.

On a standard twisted cable the connectors after the twist are usually for drive A: whereas the connectors on the untwisted section are for the B: drive..

The other thing that I remembered is that 5.25" drives normally had a "card edge" connector, rather than a couple of rows of pins like you find on 3.5" drives. I had forgotten that too. So when buying floppy cables, if you want a "standard" one you need both card edge and the 34 pin female connectors, with a twist in the cable.

Maplin's still sell these cables, so I've now got the correct one (I think). Hopefully I will be able to correctly connect my RQDX3 disk controller to my RX33 disk drive now. Watch this space...

Z88 Serial Cable

One of the things that was good about retro computers was the User Manuals.  In my Z88 manual, it describes how to make an RS232 cable that will work with its serial port (the port on the Z88 has a non-standard pinout).  So I made one:

Home made Z88 RS232 cable

It was made from bits that I had lying around (as you can tell).  Mostly stuff salvaged from old PCs in fact.  Note the USB adaptor on the end.  It's clunky ... but it works.  I could easily make a better one (one not made from junk perhaps).