[Oberon] oberonnet of things

[Chris Burrows]

> -----Original Message-----
> From: Bill Buzzell [mailto:captbill279 at gmail.com]
> Sent: Sunday, 23 August 2015 12:30 AM
> To: oberon at lists.inf.ethz.ch
> Subject: [Oberon] oberonnet of things
> 
> Doesn't your RISC processor use external SRAM? Is there a minimum
> BRAM requirement? I was under the impression we would be using the
> same flash ram chip that populates the FPGA with at startup for the
> RISC OS, and BRAM only holds user space programs (pulled from the
> flash ram).
> 

The RISC processor is not mine - I'm just using the Project Oberon 2013
RISC5 processor. The OS core and applications are loaded into SRAM from the
SD card not from flash RAM. The flash RAM only stores the Verilog code and
just enough bootloader code to load the OS from the SD card. This is as
specified in Chapter 14 Building and Maintenance Tools of the Project Oberon
documentation. I'll be using Stage 0, 1, and 2 of the Startup process and
stopping at the point "... establishing a working file system." Instead of
then loading Oberon I'll be loading a simple command-line processor that
will allow you to: 

* Upload compiled Oberon object (*.rsc) files via a fast (115200 Baud) RS232
link
* Store them to the SD card
* Execute them from the SD card

This is nothing new - it is the technique used by Niklaus and Paul when
developing Project Oberon. The difference is that am using a Windows-based
IDE (Astrobe) to do it all. 

Initially this will be implemented on the existing available Project Oberon
hardware (Digilent S3 Starter and Saanlima's Pipistrello) with external
SRAM. However, as the OS core doesn't need VGA, HDMI, Mouse, Keyboard and
all the GUI-related code, the RAM requirement is significantly reduced. 

Eventually I hope to be able to eliminate the external SRAM and target FPGA
devices with sufficient BRAM (e.g. 128 KBytes?). I favour The Spartan 6 LX45
as it the device used on the Pipistrello board which should make it as easy
as possible to prove the concept. If it works it should allow for simpler
(but not necessarily cheaper!) board designs and more FPGA pins available to
be used for other purposes. 

All of the above may well be off the topic 'oberonnet of things' as my plans
do not involve Internet-based targets. However, the tools might still be
useful for others who are interested in working in that space,

Regards,
Chris

Chris Burrows
CFB Software
http://www.astrobe.com