polpo

Hardware design came first but the design did have to take into account some of the constraints of programming PIO. I had to make sure certain signals were on adjacent pins, since the range of pins you must set for in, out, set, or sideset pins in a PIO program must be contiguous. I did have to do another board spin when I realized an error I made with some of my pin orderings.

I went for an 8-bit mux/demux to multiplex the 8 data pins and lower 8 bits of the address because I thought it'd be faster, but I do have to delay quite a bit in the PIO program while I wait for the mux to switch. Given the very high speed that you can feed serial data into a PIO, a couple of high speed shift registers might have worked just as well and would have saved on GPIO pins which are a very precious resource.

Thanks for posting this! I'm the author of the project and I've seen it pop up here on HN a few times when searching but I haven't seen it make it the front page until now.

It's been really fun pushing the limits of the RP2040 microcontroller and learning how to use its PIO capabilities has been eye opening. I've created PIO code to handle the ISA bus and interface with SPI-based PSRAM at higher speed than I could with the RP2040's built-in SPI peripheral.

It's on the list of things I want to support eventually. A friend I collaborate with on Discord is working on Sound Blaster support for his Pico-based retro PCMCIA project and I plan on using his code.

I'd adapt DOSBox's SB code but it's surprisingly complex - DSP support for the whole gamut of SB cards from the Sound Blaster 1.0 to the Sound Blaster 16 are in the same source file, and extracting the parts that I'd need would be more pain than I'm willing to deal with right now.

TonyTrapp's comment below raises a good point – I've tried to focus on emulating sound cards that are harder to find and are possible to do on the Pico. Old used Sound Blaster compatible cards are still relatively available and affordable, compared to the GUS or genuine MPU-401s with intelligent mode. CMS compatible boards are also hard to find, and Tandy compatible boards that you can plug into a normal non-Tandy PC are solely available via DIY projects.

PIO is indeed awesome! A while ago I was wondering if the RP2040 could be used as a scandoubler (and talking about it with the Chrissy who left a comment on your blog). I was originally discouraged and decided to not pursue it because the ADCs on the RP2040 are just too slow to capture video, so I'm happy to see the results of your effort!

I ordered a HAND 386 before it was removed from sale. The order hasn’t shipped yet and I’m trying to not get my hopes up too much that it will actually ship. I was going to use it was a portable testbench for my RP2040-based ISA card emulation projects.

About 10 years ago I applied for a software engineering job at a startup that had the title “System D Engineer.” I thought it was the perfect distillation of what it’s like being an engineer at an early stage startup. I got the offer and I probably should have taken it. It would have been interesting and the startup had a successful exit!

Yep, I am.

Welll.... the RP2040 is a dollar and can be overclocked to 300MHz (peripheral clocks get a little weird around that point, but they can be clocked down).

I’ve been around Unixes since the early 90s and was around for the transition away from telnet and I only learned about this about 5 years ago. Shoulda read the whole man page, I guess.

It's the opposite of excessive. If you need scan conversion, which you almost certainly do, this is far cheaper than just about anything else you can use to get a usable video signal out of a compact Macintosh.

Compact Macs have a horizontal scanning frequency of 22.2kHz. Good luck finding an LCD that will sync to that.

Fun bit of trivia: Compact Macs also used the video scanning sync timing to feed the audio DAC, producing 8-bit audio at 22.2kHz. Pretty good for 1984!

You're exactly describing the base model Nissan Leaf before the 2018 models. And base models of the 2018 and later Leaf are still relatively spartan.

Our house has 100A service and we use a 30A car charger and have never popped our main breaker. On a hot day when the AC is likely to run, I'll hit the button on my car charger to delay charging to the middle of the night when we won't be running the electric dryer or stove.

ISA is very forgiving timing wise. As long as you have the data on the pins when IOR or do your read by the time IOW is deasserted by the chipset you’re fine. And you can always deassert IOCHRDY and get all the time in the world to respond (within reason).

I had some very successful experiments with bit banging ISA on a Raspberry Pi 3 and 4 a while ago: https://github.com/polpo/pigus I quickly moved over to a Raspberry Pi Pico because it's much better suited to such things. You need more than a couple I/O pins, though... to do real ISA (i.e., not LPC) right, you need more GPIOs than what the Pi gives you. But muxing the data/address lines is enough to give you back what you need.

I'm the creator of PicoGUS... PIO is kind of like hardware assisted bit banging. You program a very simple, extremely fast computer (aka the PIO peripheral on the RP2040) to do the bit banging for you. :)

I'm not sure where I learned it, but I've found that in many older elevators in the US, pressing door close simultaneously with the floor number will also get the doors to close immediately.

I'm the author of the project, I know this post doesn't have many votes but I'm happy to answer any questions about it.

A while ago Ron Gilbert laid out what it'd look like if and when he was able to make another Monkey Island game: https://grumpygamer.com/if_i_made_another_monkeyisland. He said he'd fork off the Monkey Island canon after the 2nd game, but also "that doesn't mean I won't steal some good ideas or characters from other games. I'm not above that." So I guess Murray (and using Dominic Armato as the voice of Guybrush) are part of that.

Especially since a large number of people are probably downloading the app in a panic at the airport on crappy overloaded WiFi or cell signal.

Polaroid even capitalized on this a bit – they produced a radio that ran on the batteries in spent film packs in the 1980s.

“Open hardware” is a pretty generic term and OSHWA doesn’t have a monopoly over how people use it.

I wouldn't paint with such a broad brush. I've recently gotten way into retrocomputing, DOS included, I absolutely lived through that era. I spent my formative computing years in the early to mid 90s deep in DOS, mostly playing games, watching demos, listening to and writing tracker music, and doing pretty rudimentary C/C++ programming.

At the beginning of this year, I built an AMD K6 machine, got my Gravis Ultrasound card working again (which involved ordering a replacement mixer chip from China), and have had an absolutely wonderful time reliving my early computing experiences. And yes, that also includes fiddling with IRQ settings, maximizing low DOS memory, etc. Would I do day-to-day work in this kind of environment? Hell no! But it's a really fun distraction.

In 1999 I ran a mail server with qmail that handled incoming and outgoing mail for my personal domain and also a somewhat large (20GB) pirate MP3 FTP site, all from a server in the closet of my campus dorm room. The campus IT never said a word!

It also means your phone's battery is not draining while you're playing music. I use spotifyd on a Raspberry Pi and it's pretty wonderful.

As a part of the sale of HGST to WD, Toshiba got assets to produce 3.5” hard drives from HGST. I’d consider them the true heirs of HGST, and their good reliability as shown in Backblaze’s studies bear that out.

The great thing about TW2002 is that it was simple on the surface, which made it accessible. You could have fun warping around, trading goods, but then eventually you'd start digging and find the incredible depth in the game. The first time I stumbled on the Starbase blew my mind, and it just kept on going from there. Getting a Federal Commission (or going evil), terraforming planets, building citadels, finding dead ends in space to set up your planet, setting up corporations...

I have a T2i that I use with the EOS Webcam Utility and it works just fine despite not being listed as compatible.

The original URL, the highly memorable http://www2.warnerbros.com/spacejam/movie/jam.htm shows as pretty consistently available on the Internet Archive since 2003.

How many colors were you able to get with moving graphics? From the article the CRTC hacking needed to get the last 512 colors is too CPU intensive for anything but static images on an 8088.