Gigatron Hackers

If you do not want to do make install and want to run glcc from the build directory, the cleanest solution is to create a directory $HOME/bin, make sure it is in your PATH, and have symlinks from there to the glcc executables in the build directory. For instance my bin directory contains this becaus...

Just added binary constants to the compiler. I also added a map overlay "bare" to compile something that do not use libc at all and skip the overhead. Such programs have to do everything by hand. There is still some stack management overhead because C allows recursion. So to make a program...

In an attempt to improve the virtual interrupt system (the one that diverts the vCPU whenever frameCount wraps over), I wrote native instructions to save and restore the full vCPU context and arranged a way to have this done automatically when a virtual interrupt occurs. The rationale is explained i...

It turns out that binary constants are not in the C standard!
Yet GCC implements them and C++ requires them.
That's easy to add.

It seems that there is a promising path using the Adafruit floppy interface https://www.adafruit.com/product/5679 and a Raspberry Pico because they also provide a nice controller library https://github.com/adafruit/Adafruit_Floppy/ with read support (write support seems to be under development). One...

If I had the time, I would use the RP2040 version and program it to act as a SPI device obeying a subset of the SD card protocol. Then the SPI browser would work out of the box. As for writing to the floppy, I always meant to add an OS layer and writing support to the SPI SD interface. The idea is t...

Why no DEC instruction? Having a DEC(b) instruction that runs as fast as INC(b) would take four precious bytes in page 3. Having a DECV(v) that runs as fast as INCV(v) would take two precious bytes in page 3. I have only four free bytes left in page 3 which I believe are best kept to organize a new ...

You can use program gt1dump (in the Utils directory) to look at GT1 files.

Also: only the first segment can have hiAddress=0. Otherwise it means that the GT1 file is ending with an exec address.

See function. GMem::load() in https://github.com/lb3361/gigatron-rom/ ... z/gt1z.cpp

Phibrizzo wrote: ↑23 Jan 2024, 18:44 I was based on https://github.com/lb3361/gigatron-rom/ ... ummary.txt

LUP is an instruction whose meaning has been hideously perverted by the return-from-interrupt mechanism

Hello :) I have a few questions. 1. In documentation, RTI (Return from interrupt) is a sequence of asm codes. Latest is LUP. What is the parameter for LUP? Any? 2, In the same documentations wrote, a LUP changes vAC. Then for what vAC is saved if interrupt came? Are you speaking of the file in dire...