Update from 26th January 2019:

Symbiote - eZ80 Co-Processor for the SAM Coupe

Quick refresher of what Symbiote is. In 1995 my Quazar Surround soundcard gave SAM stunning digital surround sound. It’s been crying out for an update for years so it was originally my intention just to provide a tweaked soundcard using modern parts and possibly expand it with some external memory. Despite mentioning external memory back in SAM Revival 25 and on my website there really wasn't any real interest in that, afterall external memory was introduced by SAMCo back in 1992 for the SAM and apart from a few SAM programs which used it for RAMdisks it really ignored, so that idea was not one I lingered on.

So for Symbiote I decided a fresh, new approach was required. To drastically improve on the past capabilities without hanging onto anything that would be underutilised. Luckily, I already had a new design I could go back to. Back in 2003-7 I had been developing and prototyping a concept I had for a new SAM. Yes, that's right, I had plans for a new SAM way back then, into which I had single handedly put a lot of time, effort and money and it had progressed rather far. If you had been reading SAM Revival magazine you would have followed a few snippets of the work I had done through a few of the projects I had revealed - such as the prototype Mayhem Accelerator to use a faster Z80, as well as some non-descript photographs in the 'SAM Spy' sections. Plus the Trinity Ethernet Interface stemmed from that work too when I was looking at mass storage options - I did afterall need something to test out SD cards! But I had never revealed the bulk of the work which I had up and running that would have formed the core the system.

I've already had a few chats with SAM programmers and the ideas people are having to take advantage of the additional processing power of Symbiote are quite astonishing!

Where does Symbiote currently stand?

Prototyping and testing of all the subsections is completed. The next stage is preparation of the final hardware, firstly with the design of a new eZ80 sub board with the final memory configuration and DACs, essentially all the surface mount parts on a four layer PCB. After that combining all the rest of the hardware into the main board and the construction of an initial batch of interfaces for final testing, developers, complete the 'SAM in a Can 2's and anyone keen enough to start tinkering with it!

Original Post:

In 1995 my Quazar Surround soundcard gave SAM stunning digital surround sound. It’s been crying out for an update for years so it was originally my intention just to provide a tweaked soundcard using modern parts and possibly expand it with some external memory. Despite mentioning external memory back in SAM Revival 25 and on my website there really wasn't any real interest in that, after all external memory was introduced by SAMCo back in 1992 for the SAM and apart from a few SAM programs which used it for RAMdisks it really ignored, so that idea was not one I lingered on.

So for Symbiote I decided a fresh, new approach was required. To drastically improve on the past capabilities without hanging onto anything that would be underutilised. Luckily, I already had a new design I could go back to. Back in 2003-7 I had been developing and prototyping a concept I had for a new SAM. Yes, that's right, I had plans for a new SAM way back then, into which I had single handedly put a lot of time, effort and money and it had progressed rather far. If you had been reading SAM Revival magazine you would have followed a few snippets of the work I had done through a few of the projects I had revealed - such as the prototype Mayhem Accelerator to use a faster Z80, as well as some non-descript photographs in the 'SAM Spy' sections. Plus the Trinity Ethernet Interface stemmed from that work too when I was looking at mass storage options - I did afterall need something to test out SD cards! But I had never revealed the bulk of the work which I had up and running that would have formed the core the system.

Symbiote is a co-processor for the SAM. Featuring 8 DAC sound channels, four and a half megabytes of RAM, the main core of Symbiote is focussed around a Zilog eZ80 processor at 48MHz. The far superior architecture gives the equivalent of over 32 times the raw processing power of the SAM's 6MHz Z80. Zilog describe the eZ80 as a Z80 on steroids and they aren't wrong, it's a real powerhouse of an 8-bit processor! If you can code in Z80 then adapting to the eZ80 should not take you long at all. Despite the jump in power the archetecture inside is just an expanded version of Z80.

Sound wise Symbiote will offer full backwards compatibility with the original Quazar Surround soundcard when running in legacy mode (which it defaults to on startup) but the interface will be light years ahead when running its own native code, both for sound generation or other processing tasks on behalf of the SAM.

I have to stress that Symbiote is not just a replacement for the Quazar Surround soundcard - it’s a whole new processor system added to the SAM Coupe. Think of what would be possible if a game engine is running on the eZ80 and data is passed back to the SAM’s Z80 to display. There's so many exciting possiblities in terms of sound, games, emulators etc. I've already had a few chats with SAM programmers and the ideas to take advantage of the additional processing power of Symbiote are quite astonishing!

If you follow my twitter you'll have seen bits and pieces of news as I finalise the production design, most recently testing the memory chips I will be using. For much more thorough information and more of the backstory from when I was working on my concept for a new SAM please show your support for what I do by preordering issue 26 of SAM Revival as that will have all the latest news, specifications and info on Symbiote.