Category Archives: Retro Computing

FPGA recreations of old computers

ZX Spectrum on Altera DE1 – Teaser

Last week I was made aware of this post on RS DesignSpark about a project, currently in the very early planning stage, to build a Sinclair Spectrum on an FPGA.  As it happens I have a similar project well under way, and I have promised to write it up…

Several years ago I implemented most of the ULA in VHDL on a MAX7000 CPLD, mainly as an exercise to brush up on my HDL.  I didn’t have enough space to fit the keyboard interface so it was pretty useless, but it did boot!  The complete system used a pair of SRAMs, real Z80 and the Sinclair ROM in flash.

Back at the beginning of this year I decided to brush up on my HDL again and I bought myself an Altera DE1 development kit.  The heart of this board is a Cyclone II FPGA with a range of support hardware including 512KB SRAM, 8MB SDRAM, 4MB flash, an I2S audio codec, VGA port and the usual switches, LEDs and buttons.  I would highly recommend it for anyone looking for a relatively cheap way to play with FPGAs.

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