tranZPUter FusionX Is a 500 MHz Z80 Drop-In Replacement Based on a Dual-Core Arm Cortex-A7
Available for Sharp MZ-700, 80A, and 2000 computers.
The Z80 is an eight-bit microprocessor found in some vintage computers. And while modern Z80 chips are available today, they do not significantly extend the capabilities of the originals. However, a UK-based software engineer, Philip Smart, has a project to change that. The tranZPUter FusionX is a 500 MHz Z80 drop-in replacement based on a dual-core Arm Cortex-A7. It currently targets the Sharp MZ series of computers.
The tranZPUter FusionX is a combination of a main board (FusionX) and a daughter board. The FusionX contains a SigmaStar system-on-module (SOM) and an Altera 7000A MAX CPLD.
The 29 by 29 millimeter SoM contains a dual-core Cortex-A7 running at 1.2 GHz with 128 megabytes of RAM and 256 megabytes of Flash storage. It also has connectivity support for Wi-Fi (built-in radio), an SD Card, and a USB port. The stamp-sized computer runs Linux with a kernel driver for emulating the Z80 with Manuel Sainz de Baranda y Goñi's portable (C-based) Z80 emulator.
FusionX can emulate an accelerated Z80 running up to 500 MHz! And two-megabyte chunks of the SoM's RAM can be allocated (as banks) to the host.
However, FusionX is not the first modern Z80 replacement project. Smart based the concept on a project called tranZPUter. That project does the Z80 emulation in FPGA instead of software.
An Altera CPLD sits between the host computer and the 1.2 GHz SoM. The primary purpose is cycle-accurate Z80 timing. It communicates to the SoM via a (modern) high-speed SPI bus. The CPLD also provides logic-level translation between the vintage 5 volt and modern low-voltage signals.
A FusionX board alone is not enough to replace a vintage Z80. A host-specific daughter board connects FusionX to the host. For the Sharp MZ-series computers, Smart found that the CPU orientation of the MZ-80A and MZ-700 was different. Also, by making a host-specific daughterboard tranZPUter, FusionX can intercept other signals to extend functionality.
For example, the host computer can now take advantage of the dual-channel (stereo) 48 kHz digital-to-audio converter (DAC), video resolutions up to FHD (1920 x 1080), Wi-Fi, USB, and other peripherals on the dual-core SoM.
There are daughterboards designed for the Sharp MZ-80A, MZ-700, and MZ-2000. Smart says that development work for the Amstrad PCW-8XXX and 9XXX is underway.
This GitHub repo contains the schematics (as PDF), PCB files (as Gerbers), and software. You can purchase a tranZPUter FusionX on Tindie for $399 (before shipping.) Smart will provide a host-specific daughterboard and an SD card with software for the FusionX board and host computer.
