These were Amstrad's most successful PC compatibles: Amstrad PC 1512 & 1640
Although it was a late debut, Amstrad designed a well packaged PC compatible in 1986. The Amstrad PC 1512 offered 512KB RAM (expandable to 640KB), a CGA or a HGC graphics mode with an appropriate monitor, at least one 360KB floppy drive and a hard disk drive (implemented in several variants, mostly MFM).
Later, Amstrad replaced the PC 1512 with the PC 1640, which offered 640KB RAM, and also EGA graphics (if you had the proper Amstrad monitor in the same package).
The PC 1640 did not offer different mainboards for the 3 monitor types (CGA, EGA, Mono). Hercules Graphics looks very good (comparable to mono mode Atari ST):
The mainboard of the PC1512 was easily expandable just by adding 128KBit DRAM chips (see red boxed area):
There are only 8Bit ISA BUS slots, although the 1512 and 1640 has an Intel 8086 CPU.
No real choices for graphics card upgrades were existing, but some placed a Hercules InColor into the 1512, and with that combination, even a third-party EGA screen could be added, although the Amstrad PC 1512 and 1640 get their power from the original Amstrad monitors only...
BIOS settings could be changed only by using a software named "NVR.EXE".
Also interesting: Amstrad offered the PCs with GEM Desktop, not MS Windows.
More infos about early Amstrad PCs can be found at John Elliot's pages.
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