Re: Building an Apple II from scratch

["Michael Pender" <mpender@hotmail.com>]

Patrick Schaefer <PSchaefer@epost.de> wrote in message
3F15A39E.E6F0BD69@epost.de">news:3F15A39E.E6F0BD69@epost.de...
> Michael Pender schrieb:
>
> > I expect that all of the TTL latches and glue logic could be
incorporated
> > into a single PLA/PLD by now, but the 6502/65816 core probably still
> > requires a chip all by itself.
>
> Many 6502 ("RISC") cores are available as VHDL code for free. You can
> build an Apple II system using a few FPGA chips plus memory. If you want
> to pay for a 'real' ASIC, SRAM and flash ROM can be included, too. This
> would allow you to build a single-chip apple.

The problem with trying to implement a RISC core in VHDL is that FPGAs
generally don't have a large enough gate count to make it work.  I'm
doubtful that an off-the-shelf FPGA can be configured to include the 6502
core, ROM and SRAM.

Glue logic is one thing, but FPGAs do not make for efficient implementations
of memory.

- Mike