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 [ 3 posts ] 
 BugsBoard: a Forth MCU on the Digilent Cmod S7 board 
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Joined: Mon Jan 22, 2018 2:49 pm
Posts: 19
BugsBoard is an improvement on my previous forthBoard project.

The instruction set has been further optimized for DSP apps.

BugsBoard_Primer.pdf is at https://drive.google.com/file/d/14iPt_j ... sp=sharing

The Downloads section has a link to the entire source code.


Tue Aug 29, 2023 10:20 am

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1799
.
Some interesting ideas in there! From your doc:

Quote:
The data and address widths are 18 bits. 8-bit chars are right-justified 18-bit quantities.

Registers:
1) the 16-bit program counter (always points within 64Kx18-bit RAM)
2) the 18-bit instruction packet register at the heart of CPU control logic
3) the 16x18-bit parameter stack
4) the 16x18-bit return stack
5) the 1-bit carry out from the most-recent add

The program counter addresses complete instruction packets containing 1 or 4 instructions, not the individual instructions
within a packet.

A Cooley-Tukey 512-point complex radix-2 DIT FFT has been timed to run in 390894 clock cycles or ~8.14 ms.


Also, for reference, 48MHz, single-cycle access to on-chip RAM.


Tue Aug 29, 2023 12:55 pm

Joined: Mon Jan 22, 2018 2:49 pm
Posts: 19
Hi BigEd, it's been a while.

It's amazing what can be done with 19 instructions. I'm having a good time with audio apps (e.g. FM synth, IIR lowpass filter) at a 46875 Hz sampling rate.

I think BugsBoard would be a good trainer for modern youngsters, like we enjoyed in the 8-bit days.


Tue Aug 29, 2023 10:12 pm
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