Hello from Binary Dinosaurs!

[Witchy]

Hello folks,

Witchy here from Binary Dinosaurs in the UK. Thanks to Ewan for the nice welcome email!

Since I'm exhibiting one of my Microbees on Saturday at the Centre For Computing History in Cambridge UK I thought it was high time I joined the forums after owning 4 Danish/Swedish Microbee IIs for the last 15-20 years. None of them came with the 'grey cable' so initially I threw one together just to see what worked. Last week I made a proper shielded one so now I should be able to load software. 

Only one of the machines works so after the weekend is done I plan to fix the other 3, which means I'll be looking for hints on common chip failures and failure modes for the machine. Any help will be gratefully appreciated  

A little history. I've been collecting machines since 1998 when I found an Enterprise 64 in a wet field with a muddy bootprint on top. I realised that if I could find one of these then most things I'd wanted as a teenager could now be in my grasp. And they were, those machines (C64, Amiga 1000, Atari ST etc) and many many more. At last count I was up to around 450 or so. The website's total is a little out of date.

I let the website go fallow from 2003-ish up to 2015 when I picked up a soldering iron again and started the mammoth task of repairing collection items that had died or were dead when I got them.

Microbee page: click me! There's bound to be inaccuracies - I wrote that back when I got the systems.

Cheers all!

Witchy

[ChickenMan]

Hi Witchy and welcome to the forum

I emailed you back in 2015 requesting dumps of your Microbee roms as your site has a pic of one of them showing microbee basic_5.22d, with the d on the end indicating Danish version, which we didnt have in the Repository.  You sent dumps of all your roms (Danish & Swedish) and pic of the keyboards  which differ from our normal English models. so I thank you again for all that.  They are all in our Repository

Would be good to get your other 3 Microbee's going, just ask in the forum and I'm sure we will be able to help you get them going.

[MbeeTech]

Hello Witchy.

I've been to the Centre for Computing History. I visited in 2017 while I was in the UK.
Fantastic place. Jason did an interview and I rambled on a bit. The videos are on Youtube.
They have a couple of Microbees there. A Rom based machine and a Premium Plus.
The Premium Plus was not working properly while I was there and needed some attention.
I can't remember whether the other machine worked or not.

I regards to fixing your other three bee's, the first thing to do is swap the top boards from the dead ones into
your working one and see if they work. That at least starts to narrow down the fault finding : top board / bottom board.
You may find if you clean up the contacts on the 2 x 25way pins strips and plug / unplug the top boards from the bottom
a few times that the machines start working. This is quite common.

[Witchy]

Hello! I'd forgotten about dumping all the ROMs, it seems like a different lifetime ago now! Glad to be of service, the retro community thrives on cooperation and it's always great to be part of preserving the history of the machines. Looking around the repository it's making me realise just how much 'bee stuff is out there that I had no idea about.

Ewan, I remember watching the video now you mention it; I wish I'd known at the time because I was only half an hour-ish away by car - I was workshop based then, in the next town over (Newmarket). It would've been nice to call in and say hi. You've answered the first question I was going to ask about troubleshooting, I'm guessing that the 'bee can't tolerate a single RAM chip failure so if one goes they won't boot at all. The RAM chips are all 6116 aren't they? I have spares of those so a quick poke with the scope might find some dead ones. I read on the forums last night that the 6545 is also prone to failure so that'a another thing to check.

Cheers!

[MbeeTech]

I'm guessing that the 'bee can't tolerate a single RAM chip failure so if one goes they won't boot at all.  

Cheers!

It depends on where in the memory space it is.  If it somewhere in the middle, basic will still boot, but if for example it is where basic stores
its scratch pad / system variables etc., it may not.  Also, If it is at the start of ram, it probably wont work but should at least initialize the screen and
throw a wobbly.

The RAM chips are all 6116 aren't they? I have spares of those so a quick poke with the scope might find some dead ones.

Yes, the ROM based bees use 6116 chips for their main memory, unless you have a late production one that may have 4 x 6264's instead.

I read on the forums last night that the 6545 is also prone to failure so that'a another thing to check.

Simple chip swap from dead machine into your working one will verify whether the 6545 is working o.k.

[Witchy]

Yep, it's good that the major chips are socketed! That's for next week once I've recovered from the weekend's exhibition.