Q. According to the manual my issue 2 Spectrum has high-resolution graphics of 256 x 176, but according to other computer magazines it should have 256 x 192. Could you please explain this?

Recently I read a magazine which gave a detailed review of the Spectrum's insides. I then opened up my Spectrum and found that all the chips had different names from the ones in the magazine. Also the wiring of the Z80 chip is totally different. I wonder if this had anything to do with the graphics problem.

J. Henderson
Newmarket, Suffolk

A. First of all, you don't have a graphics problem. When you're building a user-defined graphic, you do so on an 8 x 8 grid, right? Now, if you multiply the Spectrum's 32 columns and 22 rows, you get a graphics screen of 256 x 176. It's a bit naughty to talk about a screen depth of 192, as this takes you into the report line section (2 x 8 = 16, and 176 + 16 = 192) but it's not quite wrong.

As far as the insides of the machine are concerned, you'll find a considerable variation between machines, and this doesn't just apply to the Spectrum. Micro manufacturers, particularly at the cheaper end of the market, will buy in chips from a number of different sources, so what's written on them will vary a lot.

And as machines get further into their life, minor modifications will be made to the circuitry and to the general layout of the board. In most cases this will make no difference to the machine in question - it's simply a more logical and efficient way of doing things. There is a slight difference between the issue 3 Spectrum and the earlier models, but really it's negligible.