Difference between revisions of "472"

Revision as of 13:29, 3 June 2009 (view source) Ythcal (Talk | contribs) (ROM information) ← Older edit		Revision as of 13:45, 26 October 2009 (view source) Trotzdem (Talk | contribs) (English expression was improved) Newer edit →
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	The reason [[Amstrad|Amstrad]] released a special version for the spanish market was a law ([[RD 1250/1985|RD 1250/1985]]) that said that every computer with up to 64kb should adhere to some rules - namely, have extra keys for the spanish language, and the video hardware had to be able to display spanish characters; otherwise an extra tax would be levied. So Amstrad soldered in an extra 8kb which was not, however, usable by the machine since it was not connected to anything else. Later on Amstrad released a 472 with a proper spanish keyboard and the 8 extra kB as well. [[Image:Amstrad 472 motherboard.jpg|thumb|right|200px|Left side of the CPC472 motherboard, revealing the location for the presumely 8KB expansion memory.]]		The reason [[Amstrad|Amstrad]] released a special version for the spanish market was a law ([[RD 1250/1985|RD 1250/1985]]) that said that every computer with up to 64kb should adhere to some rules - namely, have extra keys for the spanish language, and the video hardware had to be able to display spanish characters; otherwise an extra tax would be levied. So Amstrad soldered in an extra 8kb which was not, however, usable by the machine since it was not connected to anything else. Later on Amstrad released a 472 with a proper spanish keyboard and the 8 extra kB as well. [[Image:Amstrad 472 motherboard.jpg|thumb|right|200px|Left side of the CPC472 motherboard, revealing the location for the presumely 8KB expansion memory.]]
−	The 8KB "extra" memory, was in fact a single [[4164|4164]] DRAM chip. This chip stores 64 Kbits. Its data bus was only one bit. So, it weren't unable at all to use this chip to have 8 KBytes, as the Z80 needs memory to be 8 bits wide. 	+	The 8KB "extra" memory, was in fact a single [[4164|4164]] DRAM chip. This chip stores 64 Kbits, but its data bus is only one bit wide. So, it wasn't possible at all to use the so called 8 KByte memory expansion, as the Z80 needs the data bus of the memory to be 8 bits wide. 
−	As there were no space for a new chip, Amstrad designers took off one of the ROM chips, and put it in a daughter board, along with the 4164 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 supply pins were not connected!!	+	Because there was no space for a new chip, Amstrad designers took off one of the ROM chips, and put it in a daughter board, along with the 4164 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!!
−	While based on the CPC 464, at least some of the 472 got the ROM v2 with [[Locomotive BASIC]] 1.1, which normally was built into the CPC [[664]].	+	While based on the CPC 464, at least some of the 472s got the ROM v2 with [[Locomotive BASIC]] 1.1, which normally was built into the CPC [[664]].
	After the rule changed there was also a CPC 472 with non-spanish keys available for a very short time. The CPC 472 with spanish or british keyboard is very very rare.[[Image:Amstrad 472 detail motherboard.jpg|thumb|right|200px|Motherboard close-up, showing the "8KB" extra memory, next to the 40037 ROM chip.]]		After the rule changed there was also a CPC 472 with non-spanish keys available for a very short time. The CPC 472 with spanish or british keyboard is very very rare.[[Image:Amstrad 472 detail motherboard.jpg|thumb|right|200px|Motherboard close-up, showing the "8KB" extra memory, next to the 40037 ROM chip.]]
	[[Category:Hardware]]		[[Category:Hardware]]

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Revision as of 13:45, 26 October 2009

The CPC 472 was a spanish version of the CPC 464 with additional 8 KB RAM. The reason Amstrad released a special version for the spanish market was a law (RD 1250/1985) that said that every computer with up to 64kb should adhere to some rules - namely, have extra keys for the spanish language, and the video hardware had to be able to display spanish characters; otherwise an extra tax would be levied. So Amstrad soldered in an extra 8kb which was not, however, usable by the machine since it was not connected to anything else. Later on Amstrad released a 472 with a proper spanish keyboard and the 8 extra kB as well.

The 8KB "extra" memory, was in fact a single 4164 DRAM chip. This chip stores 64 Kbits, but its data bus is only one bit wide. So, it wasn't possible at all to use the so called 8 KByte memory expansion, as the Z80 needs the data bus of the memory to be 8 bits wide. 

Because there was no space for a new chip, Amstrad designers took off one of the ROM chips, and put it in a daughter board, along with the 4164 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!!

While based on the CPC 464, at least some of the 472s got the ROM v2 with Locomotive BASIC 1.1, which normally was built into the CPC 664.

After the rule changed there was also a CPC 472 with non-spanish keys available for a very short time. The CPC 472 with spanish or british keyboard is very very rare.