2020-07-12
If it’s seemed quiet here lately, that’s because I’ve been hard at work improving the Turbo Chameleon 64 ports of the Minimig core.
The two main features added since the last release are an experimential implementation of the Akiko Chunky-to-Planar converter which can be used by a handful of games to increase video performance, and an experimental P96 retargetable graphics driver.
Read more…and rattling the tin! – 2020-05-25
At long last, the AGA enhanced Minimig core finally comes to the Turbo Chameleon 64!
I teased the new core on YouTube a couple of days ago:
At the same time I announced that, in response to several people prompting me in the past, I now have a virtual tip jar – so anyone who wishes to contribute towards the development of this and other cores can now do so.
One off donations are welcome at https://www.paypal.me/robinsonb5 and will be much appreciated – but I found that pretty much everyone I spoke to about this was telling me I should set up a Patreon, too – so I’ve done that. Anyone who wishes to contribute regularly can now do so at https://www.patreon.com/coresforchameleon
I’m not planning to paywall cores or releases – that’s not my style – but as an incentive for supporters, I’ve added a “Core Supporters” page to the On-screen Menu, which I’ll use to thank by name anyone who donates £20 or more via PayPal or supports me on Patreon at the second tier.
In other news – I’ve just released the first beta – see the Turbo Chameleon 64 section elsewhere on this site.
The EightThirtyTwo ISA – Part 22 – 2020-05-04
What better way to celebrate Star Wars Day than with a multi-CPU code density shoot-out?! (Well, OK, most people can probably name a dozen better ways without even trying – but this is how I’m choosing to spend it!)
I was curious to know just how well the code density of EightThirtyTwo code generated by the VBCC backend stacks up against other architectures, so I compiled a fixed codebase, namely the OSD control module from one of the many Minimig variants, targetting 832, m68k, MIPS, OpenRISC, RISC-V ARM, and even i386 and x86-64. The results make for interesting reading…
Continue readingThe EightThirtyTwo ISA – Part 21 – 2020-04-12
One facility that’s so far been sorely missing from the EigthThirtyTwo CPU is any form of provision for on-chip debugging. That is about to change!
Continue readingThe EightThirty Two ISA – Part 20 – 2020-04-03
I’m continuing to make gradual improvements to the EightThirtyTwo toolchain, and over the last few days I’ve given my attention to linker libraries, and endian issues.
While I initially intended EightThirtyTwo to be a big endian CPU, it occurred to me early on that I could make endian-ness configurable with a generic parameter. This I did, and having set that “littleendian” parameter to “true” for testing, I never actually changed it back, so all my testing over the last few months has actually been in little endian mode!
Continue reading2020-04-02
Over the last few days I’ve been attempting to replace the OpenRisc control CPU within the DE1 and DE2 Minimig cores with EightThirtyTwo – and it’s fighting me every step of the way!
Firstly, why do I want to do this? It’s a long story…
Continue readingThe EightThirtyTwo ISA – Part 19 – 2020-03-25
One my main goals when starting the EightThirtyTwo project was to minimise the amount of block RAM I needed to devote to firmware; indeed, this was even more of a goal than was raw speed.
So how does the architecture measure up to that goal?
Continue reading2020-03-13
Long story short: I’ve just spent way too much debugging a problem that turned out simply to be an SDRAM chip’s CKE line not connected in the toplevel design file!
Continue readingThe EightThirtyTwo ISA – Part 19 – 2020-03-08
In my experiments a few days ago I noticed an odd problem with the EightThirtyTwo toolchain – namely that the following construct worked just fine:
char string[]="Hello, world!";
but the following didn’t:
char *string="Hello, world!";Continue reading
Porting an arcade core to the Turbo Chameleon 64 – Part 2 – 2020-03-06
For the Chameleon64 port of Rampage I needed some way of showing an On-Screen Display. While the core doesn’t have many options to worry about, I did want to be able to display a “Loading” message and an “Error” message if loading the ROM failed.
There are several different ways we could approach this, but as you’ll recall from part 1, we’re very short of block RAM for this project, so minimising block RAM usage will be my priority.
Continue reading