The tax is said to have been at least 15,000 pesetas per computer. For reference:
* 15,000 pesetas are '''how many?''' approximately 90 euros.(As per [http://www.unitconversion.org/eu-currency/spanish-pesetas-to-euros-conversion.html THIS] converter)* The CPC472 itself was sold for '''how many?''' 66,900 pesetas (400 euros) (For reference, prior to the introduction of this law, a CPC464 system '''how many?'including green screen monitor'' was sold for only 25,000 to 30,000 pesetas / 150 to 180 euros(as per [http://www.amstrad.es/forum/viewtopic.php?f=19&p=18955#p19008 THIS] admittedly anecdotal forum post...))
Because there was no space for a new chip, Amstrad designers took off the ROM chips, and put it in a daughter board, along with the extra 4164 RAM chip. Wires connected pins at the ROM from the daughter board to the corresponding pins on the main board. The wires were hard enough to make difficult to turn the daughter board over and reveal the trick: no wires were connected from the DRAM chip to the main board. Even the supply pins were not connected!!
=== 64K RAM Limit ===
1. Some Spanish companies may have lobbied for a tariff on imported computers, calculators and other electronic machines during the first half of the eighties (*). As a result, the Spanish Government passed an Act (Real Decreto 1215/1985, dated on 17th of July, 1985) that established a tariff on headings 84.52 (calculator and accounting machines, cash registers, etc.) and 84.53 ("automatic machines for data processing", including computers) imported from foreing foreign countries.
2. Foreign computer manufacturers lobbied themselves as a response, and forced the Government to move to an equidistant position: the tariff would be charged only on "micro-computers", that is, "automatic machines for data processing with less than 64 KB of memory". The lobbying movement was so effective that the Spanish Ministro de Economía (equivalent to the head of the British Departments of Commerce and Treasury), Carlos Solchaga, gave up his summer vacation and travelled to Mallorca, were the king was having his holidays, to have the new law signed (Real Decreto 1558/1985, dated on 28th of August, 1985). The urgency of the trip gives an idea of how powerful were foreign computer manufacturers at that time.
4. Amstrad España ([[Indescomp]]) wasn't fully satisfied by the tariff discount, and started selling their allegedly 72 KB model (Amstrad CPC 472) on September 1985 to avoid the tariff. My guess is that Amstrad UK was aware of this movement (maybe not his engineers, but at least the sales department), since the computers should arrive at Spain with the legend "72 KB RAM computer" labeled anyplace.
According to Sugar's autobiography "What you see is what you get", Amstrad knew very well what was going on. Beginning of Chapter 9: ''In August 1985, I had a panicked telephone call from Dominguez telling me there was a serious problem, that all computers of 64k and below were now banned from importation into Spain. This was because a Spanish manufacturer was producing a 64k computer and had managed to get the Spanish government to impose a rule blocking all others. This was a disaster for Dominguez and Amstrad – by now we were selling thousands of computers in Spain. [...] Fortunately, the main operating system ROM chip was fitted on the PCB by means of an IC socket; it wasn’t soldered in permanently. I suggested to my people in Brentwood that we design a mini-PCB which would hold the ROM chip as well as an extra single 64k D-RAM chip (and a few peripheral components). I also asked my technical geniuses to come up with some justification as to what this extra chip was doing, rather than be sitting in mid-air going nowhere. They did – but don’t ask me what it was! This mini-PCB, with its additional D-RAM, then plugged into the original IC socket. Based on this trick, it was true to say that the computer now had 72k of memory. We rushed the design of this mini-PCB to Orion. On top of this, we had to change the faceplate on the front of the computer which was labelled ‘64k, as well as all the packaging and the instruction manual''.
5. Spain joined the EEC on 1st of January, 1986. The Government had to align his tariffs policy with that of the EEC, and as a result it has to remove the charges on the heading 84.53 (EEC Commission Decision 1985/80908, dated on 15th of November, 1985). There was no point in marketing the CPC 472 model from then on.