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It looks like Circle (bare-metal Pi programming environment) has network, USB, and SD card drivers, plus some other possibly useful bits and pieces, so the approach of using the CPLD as a level shifter and doing everything in the Pi may actually work, as long as the drivers for current podules use s...

meylin's idea is for all the communication between the host & Pi to be via the podule interface, similar to Pi-based coprocessors on the beeb. This will result in much tighter integration with the host, including the potential for it to be used to emulate existing IDE/network/etc. podules. But I'm ...

An idea I've been batting around for a while, after acquiring an A3000 and reading all the threads about IDE and networking podules, is to make a simple podule (well, mini-podule) that contains a flash chip, a CPLD, and a header for a Raspberry Pi. The mini-podule interface has 35 pins, and we want ...

Welcome! And that is a *very* clean looking Beeb! The motherboard and keyboard look brand new...

Would you be open to uploading the .sch files (pictured in the PDFs), and possibly your kicad_pcb file with everything except the connectors and board layout deleted, for interested folks to use as a starting point? (That way we can build on a verified base.) Here are my KiCad projects, I encourage...

Based on? You have to read the datasheet to see which IO are FT as some are but not others. The F103 has a dozen or so FT GPIO in the QFP on the cheap boards. Huh... and you're right. I just rechecked the STM32F103x8/xB datasheet, and it says that almost all the GPIO pins are 5V tolerant. I wonder ...

Gave up and just started snipping pins... finally found that IC6 was the culprit. Snipping its pin 1 made the machine boot again, although the Plus 1 ROM and MGC were invisible. Scoping IC6 pin 1 showed that it was sitting around 0.1V, which would have kept the bank select register cleared. Tying it...

Usually with this sort of issue, there is a low resistance path to ground inside the failed chip. Start by measuring the resistance with the Plus one disconnected. It's probably a few hundred ohms. (Try the meter lead both ways around). Good thinking! My meter measured a total open circuit in one d...

Note that the STM32F103 (Cortex-M3) chips used in the cheap boards from China are not 5V tolerant. I believe the STM32F407 (Cortex-M4) chip used in the STM32 F4 DISCOVERY board has a lot of GPIOs that are 5V tolerant and use TTL signalling levels, so they can be connected directly to 80s/90s hardwa...

If you haven't found the Plus 1 schematic, it's attached. The reset line goes to 4 x ICs! Could be a short or a faulty IC i.e. one of the input's doing the pulling-down . . . Yep... one for the bank select latch, and three for the parallel port (main buffer, status input, and strobe output). I'm gu...

Figured out part of what's going on... scoping up the reset pin, it's glitching low in sync with the rising edge of PHI0: Screenshot 2018-06-10 22.59.01 reset glitches.png I realized that I can get the same red/yellow pattern on screen by holding down BREAK on startup, so this confirms that the prob...

Going through a lot of my old hardware right now to get it ready for exhibition at VCF West with 8bitkick and Lion , and the key thing to get going is my Plus 1... time to take another look at it :) I tried the fibre pencil approach when Dave suggested it (over a year ago now!) but it's still flaky:...

GitHub would be great. I'm starting to understand Mercurial and Bitbucket a bit better after submitting a few changes to Arculator, but I'm still much more familiar with Git

I'm doing some work with Elkulator (getting it to replay bus cycles recorded from a real machine) and there seem to be several repositories around, none of which claims to be the canonical one. I'm guessing David Boddie's Bitbucket repo is the one to go with... is that right?

As some of you may have noticed, with the help of John Kortink I've made and sold a few IDE interfaces. The building and posting of PCB's is not something I want to do long-term, so I'm making the designs available, so anyone can make IDE interfaces. This is awesome! Thank you Ian! I'm not currentl...

You should have a cream-coloured self adhesive label, which must be fixed to the Electron before attaching the Plus 3. This label is made from a metallic substance, and its purpose is to provide an electromagnetic field between the Electron and the Plus 3. This will improve the performance of your ...

A project suggestion for anyone looking for one: embed 6502Decoder into b-em so you can capture machine state from a real machine and resume in the emulator (or use an attached machine as a monitor). Update: I've started on this, except with Elkulator, because I'm hoping to show off my heavily modif...

It shouldn’t be hard to adapt this code to run directly on a Pi, using its GPIO pins for the JTAG connection. Will have to look into that when I’m back :) It’s also possible that openocd already supports this Pi GPIO method (see: https://electronics.stackexchange.com/a/101482 ), in which case you ca...

I checked in my cpld programming notes: https://github.com/google/myelin-acorn-electron-hardware/blob/master/notes/pld_programming_and_jtag.md Also started on a simple cpld programmer Arduino sketch, which should make it possible to program the cplds on my boards with just an Arduino Leonardo or Pro...

That’s right... I’ve started committing .bit and .svf files into git, so people can do that, but have been fairly haphazard about it so far. Need to do a proper sweep through all the projects and bring them all up to date!

Ah yes, that’s on my to do list

I use xc3sprog to program my CPLDs, and embed libxsvf into all the boards with MCUs so they can be programmed without a separate cable, but I haven’t documented much at all of this :/

Sounds like an excellent plan! It looks like Arculator and RPCEmu already do this, at least for the simple case (no configuration, no complicated magic like video)... here's the interface podules have to implement to be dynamically loadable: typedef struct podule { void (*writeb)(struct podule *p, i...

Just in case anyone is interested (or also working on this), I've started on an Econet implementation for Arculator. It's a high-level model of the MC68B54 chip as found in MAME and BeebEm, and I'm intending on supporting AUN, so it should be able to talk to aund and beebem's AUN code (and maybe RPC...

I've been under the impression that the only Acorn emulator that worked on macOS was Clock Signal, but I just built the sf/allegro5 branch of b-em, and it ran just fine, with only minor tweaks (here's the PR) to get it to build!

Nice work

First pull request on the way! Not much actual Mac support stuff in there so far; I'm trying to clear out all the straightforward stuff (logging, basic tidying etc) to get the final diff down to a manageable size. (Expect a lot more commits in the same vein -- I've already done all the deduplication...

I tried increasing the screen memory (by clicking on the Acorn icon and dragging the bar up to 480kB, from the previous value of 96kB), but the same error occurred. It looks like the screen memory had been reset back down to 96kB afterward, so maybe !SICK modifies it as well...?

I added in the SDL_SetRelativeMouseMode/SDL_SetWindowGrab calls from PCem, and now it captures and releases the mouse. I'll start looking at tidying up the diffs and pushing this to BitBucket over the next few days :) This self-extracting SparkPlug archive worked , after editing !Run and commenting ...

I'm unclear as to what I changed (something trivial like putting braces around something to add debug output, I'm guessing) but last night it started getting to the purple/blue POST screen, then crashing with a data abort as soon as doosmouse() ran (its writes to 0x5B8 and 0x5B4 failed), which sent ...

Here's what I think is happening. This is the code that's running: .data:0381158c 0d 15 a0 e3 mov r1, #54525952 ; 0x3400000 ; r1 = vidc .data:03811590 b8 20 4f e2 sub r2, pc, #184 ; 0xb8 ; r2 = pc-184 .data:03811594 04 00 92 e4 ldr r0, [r2], #4 .data:03811598 01 00 70 e3 cmn r0, #1 ; exit when we re...

Here's the current dump on shutdown (with the latest updates pulled in) -- R 0=228C0F6A R 4=00000000 R 8=7FFFFFB6 R12=2F802B0F R 1=03400000 R 5=08000000 R 9=036E018C R13=00400000 R 2=03816098 R 6=20000000 R10=0F802C9F R14=5F81158F R 3=FFFFFFFF R 7=00001F3C R11=80000003 R15=3F8115A3 2834004 E4920004 ...