late 1985, when the CPC6128 was introduced in Europe, Amstrad decided not to keep three models in the line-up, and production of the CPC664 was discontinued. CPC6128 The CPC6128 features 128 KB RAM and an internal 3-inch floppy disk drive. Aside from various hardware and firmware improvements, one of the CPC6128's most prominent features is the compatibility with the CP/M+ operating system that rendered it attractive for business uses. The CPC6128 was released on 13 June 1985 and initially only sold in the US. Imported and distributed by Indescomp, Inc. of Chicago, it was the first Amstrad product to be sold in the United States, a market that at the time was traditionally hostile towards European computer manufacturers. Two months later, on 15 August 1985, it arrived in Europe and replaced the CPC664 in the CPC model line-up. Initial suggested retail prices for the CPC6128 were US$699.00/£299.00/DM1598.00 with a green screen and US$799.00/£399.00/DM2098.00 with a colour monitor. In 1990, the 6128plus replaced the CPC6128 in the model line-up, and production of the CPC6128 was discontinued. The plus range In 1990, confronted with a changing home computer market, Amstrad decided to refresh the CPC model range by introducing a new range variantly labelled plus or PLUS, 1990, or CPC+ range. The main goals were numerous enhancements to the existing CPC hardware platform, to restyle the casework to provide a contemporary appearance, and to add native support of cartridge media. The new model palette includes three variants, the 464plus and 6128plus computers and the GX4000 video game console. The "CPC" abbreviation was dropped from the model names. The redesign significantly enhanced the CPC hardware, mainly to rectify its previous shortcomings as a gaming platform. The redesigned video hardware allows for hardware sprites and soft scrolling, with a colour palette extended from a maximum of 16 colours (plus separately definable border) at one time from a choice of 27, increased to a maximum of 31 (16 for background and 15 for hardware sprites) out of 4096. The enhanced sound hardware offers automatic DMA transfer, allowing more complex sound effects with a significantly reduced processor overhead. Other hardware enhancements include the support of analogue joysticks, 8-bit printers, and ROM cartridges up to 4 Mbits. The new range of models was intended to be completely backwards compatible with the original CPC models. Its enhanced features are only available after a deliberately obscure unlocking mechanism has