Topic: replacement for the Main ULA IC in the POD.

[PLOD11]

Just a thought i had last night while talking to friend about some electrical, Radio related stuff, has anyone tried to program a PIC CHIP to work as a replacement for the main IC in the Pod.

I know that these are now defunct and not available, and i know there are ways round this should it need replacing, but i am sure that a pic chip would more than do the job and would also be an exact replacement if programed correctly.

Someone may have already tried ?

John

[Karl]

As technology progresses I expect someone will come up with a replacement. Not heard of anyone doing so as yet. 

[PLOD11]

I am just getting in to this side of things, so will have a look at the possibilty of prgramming a pic chip for the POD as a first project, i have a mate of mine who is very good at all this so will look at a bit of design work, there is a lot of free software about, so it shouldn't be to hard a job, that will keep me busy for a bit.

John

[radiomarty]

Just a thought i had last night while talking to friend about some electrical, Radio related stuff, has anyone tried to program a PIC CHIP to work as a replacement for the main IC in the Pod.




Go for it Plod I would love a plug in replacement !!!!!!

[techytype]

as an 'on neded occasion' designer i had also looked into PIC programming for other projects, it takes of time to learn, once you have mastered it then you can get on a and design - but i'm not lever enough .

my designs tend to be for small run bespoke projects usually to do with security systems that need 'specials', its just not viable to otherwise to spend the time on learning it.

assuming a member has this skill already, to emulate in a PIC for the C5 Pod you would have to know all the characteristics of inputs and outputs needed to be programed into the PIC before you could proceed with design, so it makes it a tall order imo for whoever has a crack at it.

imo perhaps the way forward is to use the scooter control kits with modern displays, i got mine off Ebay for about £12 with the intention of installing it into my C5 - when ever i get the time its a battery volt indicator and condition indicator meter with alarms for low voltage, also has internal and external external temperature sensor, with a button to switch to choose between them, its about the same size as the pod display, it is LCD and backlit, so far easier to see.

intend to attach the external sensor onto the motor

if the above works out then although the C5 won't be 'original' it will have a viable alternative.

regs
alan

[PLOD11]

My next question was has anyone got the spec for the ULA chip, i have looked around on the net but not found anything.

As part of my other hobby as a radio Amateur, the pic chip has been used quite a bit in the design of logic boards to run radio repeaters etc, so we have some experience in this, but i know what you saying, it will be a bit of a long shot, but i will speak to those who know and see what we can come up with, the other option was to look at a re design of the POD circuit, keeping the led displays so that it all fits back in to the casing but using some more modern technology.

John

[Umpa]

My next question was has anyone got the spec for the ULA chip, i have looked around on the net but not found anything.

Sadly this is what prevented some guys I know from making progress.

[PLOD11]

Some where on the net apparently there is Ferranti archive, it should have details of this chip in that, just got to find it 

[radiomarty]

I think the Pod is the weakest link at the moment - with Karl / Dave cracking the gearbox issue - leaving the Pod as the main problem area. From my experience I have had 3 duff Pod's out of 4 all with the ULA being the main issue. If this can be cracked we are looking at keeping them going for a very long time - Personally I think the way to go is the same as Karl has with the gearbox IE a direct replacement even if it is 'new electronics' that can be fitted in the original housing.Keep us informed of developments and good luck !

[mike7201]

Forgive my ignorance folks, but is this ULA chip the same as used in other sinclair products?

There's a website called http://www.thesinclairshop.com which stocks replacement Sinclair ULA chips.  Here's a technical guide - http://www.retrocomputershack.com/PDF/ZX81-ULA-Doc.pdf

Looks like there are a few available, but like most Sinclair items, they're new old stock, so supplies are limited.

Is this the chip you seek?  If not, I'm sorry.

Thanks,

Mike

[PLOD11]

If it was only that easy ! 
No the ULA in the C5 is one of hundreds made by ferranti / Plessey and is unique to the C5 and controls the information displayed on the POD display and monitors the condition of the motor and battery.

As said earlier this is the weak link in the C5, and if we can't program a pic chip then we will be looking at a replacement board, with some new technology built on to a similar size board to fit into the existing POD.

So watch this space, i will be speaking to a man next week who has the ability to help with this, buts its convincing him that it is worth doing. 

[Karl]

..... buts its convincing him that it is worth doing. 

You've hit the nail on the head there mate.

I've found to my cost on previous occassions that the market for C5 stuff is really quite small !


You're right to resist the temptation to get too carried away.

[Umpa]

The ULA in the pod was custom made for the job & thats the problem 1.  As far as I am aware there are no papers on this chip & thats problem 2.

As far as originality goes we need replacement pods.  But as far as usability or 24v kits go its not an issue.

[MikeDX]

Can we get a donor ULA to be decapped so we can try and decode it? I have a (few) people in mind who would be up for the challenge, and of course once its documented there are more than a handful of people who would be up to the jobn of emulating / simulating it on a pic.

I of course at the moment don't have any c5 hardware let alone a pod..

[henzi]

A year ago a C5 with "Circuit diagrams and a prototype pic chip replacement for the somewhat dodgy ferranti ULA" was offered for sale (unsuccessfull?) at a New-Zealand auction web site:
http://www.trademe.co.nz/nz/auction-206515627.htm
So what happened to that circuit diagrams and the prototype?
Greetings from Germany,
Henning