Sinclair SCL/ULA

[Moggy]

QUOTE.

"Some things that are definitely certain:
The early issue one boards did have the ULA soldered directly. These normally have the 2C158E ULA."

I have reservations about that statement.

The first four I purchased new (to resell as well as the second hand Sinclair Hi-Fi units I was buying and selling at the time) at the outset of zeddy production all had the 2c158 ULA, all socketed not soldered direct. (I opened them up to security mark the boards in case of dishonest returns.)

I think unless any Sinclair/Timex documentation comes to the fore with a definitive answer one can only go by ones own experience which in my case says issue ones, in the main socketed, issue threes un-socketed and any thing in between probably down to user alteration. This is a wide generalisation obviously.

All a matter of opinion (all others I obviously respect) and or user experience which in my view only is based on being a buyer/seller at the time rather than a user. I don't think anything could be regarded as a certainty re the the boards manufacture, rather more of a possibility in what we believe the situation was at the time with no hard factual answer.

[Lardo Boffin]

I will start taking photos of the solder side of any I buy as I do get through a few of them!

My experience mirrors that of Mark and Moggy - many issue ones are socketed (but not all) and many issue threes are soldered directly (but not all).

Some of the ones I have seen look to have been worked on but I don’t think all of them did. Many did not show any signs of being opened before I got them.

[1024MAK]

Well, I can only point to this board as an example of an early ZX81 where all the chips are soldered directly.



So it looks like some early boards had the ULA in a socket and some did not. We will never know for certain unless a Sinclair or Timex person comes forward to tell us or as you say, some documentation comes to light.

I think the best thing to say is to never assume anything with regards to which boards have which components and whether the chips are socketed or not.

Mark

[Moggy]

I concur.

Plus knowing the amount Lardo gets through He is probably the best "modern" source of information.

(Only joshing Lardo.)

[TMAOne]

"Early ZX81"s were also available in kit form, which means a potential wildcard. I recall with questionable accuracy that mine, bought in North America, did come with sockets supplied, undoubtedly a wisdom as a hedge against my under-developed soldering skills.