I've updated the bootrom on the proof-of-concept 65Org16 system project which sits in an OHO module. I've just got to the point of loading and running a first non-trivial application program using the hex loader:


This is an important milestone because it means I (we!) can test code without needing to re-synthesise from verilog and re-load the FPGA each time (3 min to re-synth, 20 sec to re-load)

It's Bruce's latest pi program - I've line-wrapped the output for the forum. It came out in no time at all, except I've got some flow control issue with the I/O so there's a second or so's pause after the first 8 digits.

The CPU is running at just under 50MHz, and with on-FPGA RAM, so there's only 4k words.

This is the hex I loaded:


Thanks of course to Bruce, and to BitWise and Teamtempest for the assemblers, and Ross for the hexloader, and Mike for the emulator, and Arlet for the core, and to OHO for the nifty modules! (And to Garth and Electric Eye and other forum members for various input and encouragement - the core is named to reflect the forum's parentage. And VBR for starting that thread!)

Cheers
Ed

Hi BigEd, very interesting stuff!

Is the hexloader is inside the OHO module's Spartan 3 Block RAM? (ROM)
How are you transferring the HEX from your computer to the hexloader in the OHO Module?

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502

Hi EE


It's a standalone hard-coded ROM, so it doesn't consume any block RAM resources. It's 640 words.

I have a USB connection, which looks to the computer like a serial port. To the 65Org16 code it looks like a UART. To the FPGA it looks like a pair of i2c devices. On my photo you'll see the interface board which is easy to use and bread-board friendly.

Cheers
Ed

One last question...
You had to install windows drivers for the USBtoI2C device?
What baud-rate do you have it set at?

I am doing something similar on the dev boards by using a Microchip MCP2200. I've been reading up on it from other folks who have used it and have commented that it's error free up to a 200K baud rate. I may be looking for an alternative for V1.1...

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502

I don't remember needing to install a driver, although the docs do suggest that one should. I have used the board both from windows and linux (and we've used it from Mac too)

My present python script talks to the board at 19200, which is what the docs recommend for this board. Note that I'm not using RS232 at all, anywhere - this is i2c and USB, with serial being an emulation layer at the host computer side. It's not efficient, but it is easy and electrically forgiving, and I had all the parts.

I see the T65 project comes with a 16450 model, so putting a UART on-FPGA shouldn't be an obstacle. So, as you've done, using some USB-serial converter chip finishes the job. (In fact, the USB-i2c module I have only does that conversion, but the later USB-iss module on the same page and for the same price also converts to SPI and to serial, so that would also do the trick.)

Cheers
Ed

Ok cool, Thx.

Back to on-topic.

Is there a way to count the digits it is calculating out to?
That way we can use this as a base test to compare performance of a 65Org16.x variant core. We would just need some sort of timer to keep track. Maybe a hand held one would work?

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502

Bruce's program calculates to a fixed number of digits. To turn this into a benchmark that we could time, we'd probably want to:
- change the output to just store to RAM so we're not measuring i/o speed
- loop the whole thing to run several times so it takes enough time to get an accurate reading
- light an LED at the end
- time it with a stopwatch

A 65Org16 running at 50MHz should be more than 3 times faster than a 65816 at 14MHz because it has more memory bandwidth - it's not fetching and storing in 8-bit lumps. Otherwise, the two programs are very similar. I do have a 65816 which I could in theory run on, but there are lots of other interesting things to do.

Cheers
Ed