The Turbo9 Reimagines Motorola’s Basic 6809 as an Open-Silicon Pipelined 16-Bit Microcontroller

Pc engineering researchers Kevin Phillipson and Micheal Rywalt are attempting to carry again the traditional Motorola 6809 structure — by creating a brand new implementation dubbed Turbo9, utilizing pipelining to ship efficiency equal to or higher than fashionable equivalents.

“The Turbo9 is a pipelined microprocessor IP written in Verilog that executes a superset of the Motorola 6809 instruction set,” the researchers clarify of their undertaking. “It’s a new fashionable microarchitecture with 16-bit inside datapaths that balances excessive efficiency vs small space/low energy. The Turbo9R with a 16-bit reminiscence interface achieves 0.69 DMIPS/MHz [Dhrystone Million Instructions Per Second per Megahertz] which is 3.8 occasions quicker than Motorola’s authentic 8-bit MC6809 implementation.”

The unique implementation of which the pair communicate was the work of Terry Ritter and Joel Boney at Motorola, and launched because the Motorola 6809 in 1978. Designed to supply enhancements over the sooner Motorola 6800 whereas retaining supply compatibility, the 6809 added {hardware} multiplication, higher interrupts, stack registers with re-entrant code help, 16-bit arithmetic, and extra — making it one of the crucial highly effective eight-bit chips of the period. Its excessive worth, nonetheless, meant it struggled in opposition to cheaper opponents, and the launch of true 16-bit elements led to its demise.

Phillipson and Rywalt, although, aren’t keen to depart the gadget to historical past. The Turbo9 is a reimplementation of the 6809 structure with fashionable options, together with a pipelined structure that may go toe-to-toe with fashionable 32-bit microprocessors and microcontrollers for efficiency. It additionally presents as one thing in-between a fancy and lowered instruction set laptop (CISC and RISC) structure, utilizing what we might now acknowledge because the CISC 6809 structure with a RISC decoder for micro-operations.

“Present trade developments are to adapt 32-bit RISC IP for microcontroller use,” the pair clarify of the undertaking’s inspiration, “nonetheless their massive 32×32 register information and loosely encoded directions restrict their absolute minimal footprint. So with the purpose of a making a efficiency and compact microprocessor IP, we’d like an 16-bit instruction set structure (ISA). Additionally, we would like an structure that’s able to working C code successfully.”

Whereas Phillipson and Rywalt hope to see the compact Turbo9 utilized in system-on-chip (SoC) designs to ship coprocessors for the whole lot from reminiscence interfaces to audio help, or in mixed-signal chips as a digital interface to analog {hardware}, there’s one other benefit to the undertaking: it is appropriate with current software program for the 6809, making it of curiosity to classic computing and gaming fanatics because of the unique chip’s use within the Dragon 32, TRS-80 Coloration Pc (CoCo), and Commodore SuperPET, in addition to arcade boards together with the traditional Star Wars shooter.

The total supply for Turbo9 is out there on the undertaking’s GitHub repository underneath the permissive BSD 1-Clause license.