There was a professional-level CAD program, Home Designer by BRiWALL, but again, most of this work was done on PCs by the C128's era. The main reason that the C128 still sold fairly well was probably that it was a much better machine for hobbyist programming than the C64, as well as being a natural follow-on model to owners with significant investments in C64 peripherals and software. But ultimately the C128 could not compete with the new 16/32-bit systems, which outmatched it and the rest of its 8-bit generation in nearly every aspect. When the C128(D/DCR) was discontinued in 1989, it was reported to cost nearly as much to manufacture as the Amiga 500, even though the C128D had to sell for several hundred dollars less to keep the Amiga's high-end marketing image intact. Bil Herd has stated that the design goals of the C128 did not initially include 100% compatibility with the C64. Some form of compatibility was always intended after Herd was approached at the Plus/4's introduction by a woman who was disappointed that the educational software package she had written for the C64 would not run on Commodore's new computer, but when Commodore's marketing department learned of this, they independently announced total compatibility. Herd gave the reason for the 128's inclusion of a Z80 processor as ensuring this "100% compatibility" claim, since supporting the C64's Z80 cartridge would have meant the C128 supplying additional power to the cartridge port. He also stated that the VDC video chip and Z80 were sources of trouble during the machine's design. Herd added that "I only expected the C128 to be sold for about a year, we figured a couple of million would be nice and of course it wouldn’t undercut Amiga or even the C64". After Commodore raised the price of the 64 for the first time by introducing the redesigned 64C in 1986, its profit from each 64C sold was reportedly much greater than that from the C128. Specifications CPUs: MOS Technology 8502 @ 2 MHz (1 MHz selectable for C64 compatibility mode or C128's 40-column mode) Zilog Z80 @ 4 MHz (running at an effective 2 MHz because of wait states to allow the VIC-II video chip access to the system bus) (C128D(CR)): MOS Technology 6502 for the integrated floppy controller MMU: MOS Technology 8722 Memory Management Unit controls 8502/Z80 processor selection; ROM/RAM banking; common RAM areas; relocation