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Last edited: 5:25:08 pm on 12 December 2011 by 192.168.2.3

!!!Development
These are projects meant to produce saleable products in a reasonably short time frame.

An *album* includes the most interesting pictures and drawings which show the history of Merlin Hardware.
!!Plurion&reg; X6 Low Cost Computer
This will be the first machine released, and is just a small box to which you connect a USB keyboard and mouse and a SVGA monitor or TV set. It is based on the Xilinx Spartan 3 1000 programmable chip (FPGA - check out our *Avnet/Xilinx corner* for FPGA related information) and a Secure Digital card for mass storage. The main memory is a regular 184 pin DDR SDRAM board (128MB to 1GB).
!!Plurion&reg; V6 Video Game
This is a variation of the desktop X6 which includes a built-in DVD reader (and the FPGA can be programmed from the CD/DVD) and is normally connected to a TV set. USB game controllers can be used in place of the keyboard and mouse.
!!Plurion&reg; Z6 Hand Held Computer
Using a 7" LCD screen and *chorded keyboard*, this device uses the same board as the Z6 machines.

The letter indicates the form factor of the machine: X = experimental (just the board in a box), Z = screen (in honor of the ZX and Z machines from Sinclair). The number is the generation of the board design (which is 6 in honor of the Merlin 1 to 5 machines).
!License
All information needed to build these machines (schematics, PCB layouts, FPGA programming files, all special CAD tools) will be available under an open source style license. This will allow teachers, students and interested people to learn about the system at the deepest level and also to modify it if they want.

The very latest version will only be available to companies that are paying to produce Merlin computers. As soon as they get a new version, the previous one will be released to the general public.
!!Processor Designs
The reason why the heart of these computers is a programmable chip is so a custom processor can be designed to perfectly match the intended application. Several alternatives have been designed so far.
!*Plurion Architecture*
The idea is that it is easier to develop software that runs on a number of simple stack processors and on a single VLIW processor due to the complexity of statically scheduling instructions to make full use of the hardware. A very important feature is the *PICMode* scheme for implementing message dispatch. The current description shows a stack architecture based core, but the plan is to use *RISC42* instead.
!*RISC42*
This is a cleaned up version of the third design shown in the *Other* designs page. It is a nice architecture for running code compiled from C or even written in assembly language.
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!!!Research
These projects were created to gain more knowledge which could improve the projects described in the development section above. They will not directly result in products, though that might change if a project ever moves to the development phase.
!!*RNA* (Ring Network Architecture)
Is it possible to implement Smalltalk directly in hardware, ignoring the traditional Von Neumann machine separations of processing and memory?
!!*Computer in a Pen*
Could a usable $5 computer be built with today's technology?
!!*Hardware Recompilation*
This is a hardware alternative to the Self/Strongtalk style software adaptive compilation technology.
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!!!Retrocomputing
"Of all the words of tongue and pen, the saddest are these - it might have been." But rather than agree with this, I like to consider what was and what could have been. Thinking about and actually building or rebuilding machines from the actual or possible past is the hobby of "retrocomputing" or (in the case of things the could have been built but for some reason never were) "alternative retrocomputing".

A list of known *Smalltalk Computers* is a good way to see what once was, and a list of *FPGA retrocomputing* projects shows a modern way of recreating old stuff.
!!*K72*
This is a retro-computing project to see how good a Dynabook it would have been possible to implement in the early 1970s.
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!!!Older versions and variations
*Another site>http://www.lsi.usp.br/~jecel/history.html* has more information about the initial years of the project.

*Merlin Junior* was a low cost version of the Merlin 6 using the Spartan 2e. It was essentially a cleaned up version of *proto-Merlin*, which was an adaptation of the Oliver boards for a demonstration as a low cost Smalltalk computer.

The older *Pegasus 2000>http://www.merlintec.com/pegasus2000/* project generated many interesting ideas that are being resused here.

Information about a previous Merlin 6 design with PCMCIA sized modules that plugged into a main chassis:
- The *Processor Module*
- The various *IO Modules*

The next Merlin 6 was to be built from a set of standard modules. The *mechanical specifications* explain the meaning of the size codes used in the table below while the o *network* page details the interconnection between modules.

For very small configurations, the Power Source module could be replaced with a wall transformer. Either sized Tablet or a Compute Node could be a full system all by itself, but in that case storage would be limited to a single CF card.

A separate *disk* board was used in early versions, but a later plan was to use a single, generic *main board* for all modules.
!!Processor Designs
!*Oliver* implements a 16 bit processor to run Neo Smalltalk
It was inspired by the Forth MISC designs. Two pages in Portuguese describe the early *testing>Teste do Oliver* of the PCB and the *development>Desenvolvimento do Oliver* of the FPGA programming and software. They include some pictures.
!*I/O Processor*
The same stack processor that execute user code can also be used to implement i/o functions in software, but a simple RISC variation might be better for this job.
!*SqueakProcessor* is a hardware implementation of Squeak Smalltalk
It uses a microcoded architecture and a "dual image" scheme to move most of the complex functions into the software layer. Note that a RISC processor enhanced with a *PICMode* and a *BCMode* execution extensions would have a performance similar to this special microcoded design and so could be a more interesting product.
!*Tachyon*
The initial design for the Merlin 6 was based on the *Tachyon* processor.
!*dietST*
This was a 16 bit design implemented in a 4 bit serial fashion is an attempt to find out the answer to "How small can a processor be and still execute Smalltalk directly in a usable way?" The goal was to fit a complete Smalltalk computer in an FPGA with only 15 thousand gates. Since the *Plurion Architecture* can now be configured to have a partially serial operation, a special design is no longer needed.
!*CBC*
The C ByteCode architecture is a virtual machine to compactly encode programs written in the C programming language.
!*Other*
Here are a few variations based on the design for the *I/O Processor*
!*Educational Processors*
This is a list of processors designed for teaching computer architecture concepts.

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