Chances are, you have used or seen those old screens that showed the image as green on black. Today technology has advanced a lot and obviously they have been forgotten as CRT monitors did, but at the time CPCs were a real revolution because it was precisely they who allowed monochrome screens and those fluorescent greens to fall. in the I forget.
CPC, created by Amstrad to power color screens
The main reason PC makers pushed for CPCs was the visual health of users. These old screens used cathode ray tube technology to project electrons onto a fluorescent mesh, which produced the pixels we saw on screens; The problem is that inside these fluorescent screens there was phosphorus, a material that emits light when struck by radiation such as electrons and the culprit for that green color of the screens.
Over time, this technology evolved and monochrome monitors arrived, changing that green color to a white background with black letters that provided an experience similar to reading on paper … it might appear that this evolution did not happen. not much to do with the visual. the health of users, but this was not quite the case, since studies appeared in the early 80s which showed that this electronic shock, which caused flashes of light due to phosphorus, was very harmful to health and especially for people who suffered from astigmatism.
CPC is an English acronym which stands for Color personal computer, or a color personal computer. As you can imagine, this was the next evolution of PCs with monochrome displays, for the first time introducing color displays in a personal computer. The forerunner of this technology was Amstrad, which started selling the first CPCs on the market in the 1980s and early 1990s (although it is true that even with its introduction it was still possible to purchase models with a green phosphor screen (GT65 / 66), with the CTM640 / 644 in the lead.
The first CPC was the Amstrad 464, officially presented and sold on a large scale since June 21, 1984; It was designed as a direct competition to the famous Commodore 64 and the Singlair ZX Spectrum, and the entire line was so successful that over 3 million units were sold over the life of the device.
The series had a total of six different models: the CPC464, CPC664 and CPC6128 became a huge hit in the European home computer market, while the 464 Plus and 6128 Plus were hardware upgrades that simply extended life. from the Serie. of the same name but without the plus suffix. Amstrad has also released the GX4000 game console with somewhat less success.
Therefore, and what interests us here, is that the CPCs have assumed the first personal computers to integrate a color screen, and so in reality it’s not that there are any differences with the PCs we use today, they were just called that initially (or Amstrad wanted to call them that) because at that time having a color screen on the PC was a real novelty.
What equipment did the first CPCs have?
The whole family of Amstrad CPC computers was based on the Zilog Z80 processor, clocked at 4 MHz and obviously with a single core and a single thread. A curiosity of this processor is that to avoid conflicts between the CPU and the video circuits that served the color screen when accessing system memory, access to the latter was limited to certain milliseconds, adjusting each of the CPU instructions to a multiple of four cycles, and since the Z80 instructions required between three and four cycles, the resulting effective speed was reduced to approximately 3.3 MHz.
Regarding memory, the different versions of CPC had different capacities; the CPC464, CPC664, 464 Plus and GX4000 models had 64KB of RAM, while the CPC6128 and 6128 Plus had 128KB (hence their names among others). This memory could be expanded up to 512KB using memory extensions sold by third parties, and up to 4MB RAM using experimental methods as demonstrated later.
The CPC video system consisted of a CRTC (Motorola 6845) with a chip designed to form a pixelated output; They had three resolutions available: 160 x 200 pixels with 16 colors, 320 x 200 pixels with 4 colors and 640 x 200 pixels with two colors, obviously for monochrome screens. However, the original CPC video hardware supported a palette of up to 27 colors generated from the RGB color space, although the Plus series expanded this palette to 4096 colors in total.
Audio-wise, Amstrad’s CPCs used a General Instrument AY-3-8912 sound chip which provided three configurable channels to simply generate square waves and white noise, with mono output via a small built-in 4 speaker. cm with volume control. Some models had a 3.5mm jack output for stereo audio output.
Finally, it should be mentioned that these computers also had storage, but not internal, but used floppy drives, cartridges and audio tapes, as we have already explained previously in other articles; they had no internal memory.
