@bread80@mstdn.social avatar

bread80

@bread80@mstdn.social

Amstrad CPC, RC2014, Z80, Raspberry Pi Pico, TTL processors and the occasional bit of Eurorack

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bread80, to random
@bread80@mstdn.social avatar

That’s what I call a good start to the weekend 🙂🙂🙂

The only soldering error was a short between power and ground on the USB power connector.

Design wise the backplane has a couple of footprint issues, and my attempt to keep the board smaller by placing components under and between the cards is proving less than ideal in practice. The taller components are actually fitting between the cards but it looks messy and there’s potential for damage from soldered pins.

Top 3/4 view of the computer showing the vertically mounted cards. One board has a row of green LEDs lit at various brightnesses.
Side view of tue computer with video out and other connections.
Top down view.

bread80,
@bread80@mstdn.social avatar

The LEDs on the CPU card are working beautifully. My intention with these is that they’d make a useful debugging aid for builders. See them like this (and flickering in real life) is an obvious sign the machine is working without needing video out.

It wouldn’t be hard to build a test ROM for other parts of the machine as long as CPU and ROM are functional (which requires Gate Array but there are ways you cloud bodge around that).

Enable for the buffers uses IORQ so this shows IO addresses.

bread80,
@bread80@mstdn.social avatar

The sockets on the backplane have wider spacing between the sections than within. That allows cards with ‘fat’ connectors such as the video out DIN connector somewhere to sit without fouling or shorting anything.

The sound board would normally sit in the front most slot to make the keyboard connector mounted on it easy to access. In this photo it’s checking the tape motor relay on the IO board doesn’t foul the neighbouring slot (it doesn’t).

bread80,
@bread80@mstdn.social avatar

SCART to HDMI adapters for the Amstrad need a 5V input to signal their sending RGB data. This photo shows the 5V take-off included on the backplane for this purpose. I’ve snipped the end off and old PSU to use as cable and plug.

Next to it is a socket which can be used to stow that plug when not in use - to avoid it causing shorts. Here I’m using that to house the power connector on the video lead.

bread80,
@bread80@mstdn.social avatar

I’m just realising that spare power connector on the lead might be useful for powering a SCART adapter, subject to power requirements and connector type and polarity.

bread80,
@bread80@mstdn.social avatar

Next up is to assemble a keyboard lead - this machine won’t do much until I do!

But shorting some random pins on the keyboard connectors shows everything appears to be functional.

bread80, to random
@bread80@mstdn.social avatar

Imagine you have some really sensitive information which could cause catastrophe if it was allowed to fall into the wrong hands.

So you get the world’s top security expert to lock down the server using a combination of the most advanced and arcane protection protocols available.

But a group of ten year old computing students manage to hack the server.

This is pretty much the plot of Harry Potter and the Philosopher’s Stone.

bread80, to random
@bread80@mstdn.social avatar

Interesting bug Thursday.

The date picker in Quickbooks online has some lovely keyboard shortcuts. Use W or K for the first or last day of the week, as in WeeK. The same for MontH and YeaR.

But this month H moves to the 30th March instead of the 31st. I wonder if it's a leap year bug? But the rest of this year works properly, as does March 2028.

bread80,
@bread80@mstdn.social avatar

They make it very easy to give feedback, and from past experience they're pretty good at fixing bugs if you report them. One of the reasons a like Intuit and something a lot of SaaS businesses could learn from.

bread80,
@bread80@mstdn.social avatar

@semiprime I’m not sure why that would make a difference.

ash, to random

Attention customers,
Due to engineering works, the 5v rail will now be operated by a rail replacement bus service until further notice.
We apologize for the inconvenience

bread80,
@bread80@mstdn.social avatar

@ash IIRC the original ARM could be powered via the signal pins. So having a chip powered via the data bus is not without precedent...

phire, to random
@phire@phire.place avatar

TIL the dunning kruger effect is not real, apparently! time to throw out yet another file in the “what don’t we need evidence to believe because it is emotionally satisfying to do so” cabinet. ty @danderson for the link https://economicsfromthetopdown.com/2022/04/08/the-dunning-kruger-effect-is-autocorrelation/

bread80,
@bread80@mstdn.social avatar

@phire @danderson The less you know about psychology the more you think you know about psychology…

bread80, to random
@bread80@mstdn.social avatar

I apologise for not posting this earlier.

is now alive! (At least Conway's variant of alive). The initial version was slow - about four seconds per generation. It was multiplying coordinates for each cell read and write.

The second variant uses offsets into each liner buffer, and only redraws changed cells. It's now running at three to four generations per second.

The next generation of the glider.

bread80,
@bread80@mstdn.social avatar

I shall now be returning to the tedium of library routines before I do any more exciting stuff...

bread80,
@bread80@mstdn.social avatar

BTW you can read the source code for Life at https://github.com/Bread80/Quiche/tree/main/Examples/ConwaysLife

bread80,
@bread80@mstdn.social avatar

@RetroFunPL The syntax isn’t fully formed yet, but semicolons will be optional. It will use line endings as end of statement markers instead. Code can be split across lines either with an explicit \ character or if it ends with an incomplete expression.

One of a couple of features I’m taking from Ruby. A language which, mostly, makes very sensible choices.

bread80, to random
@bread80@mstdn.social avatar

See if you can spot the upside down TVS diode.

bread80,
@bread80@mstdn.social avatar

@f4grx Yup. I'm being lazy and rushing on the basis that it's the board will probably need a respin.

neosam, to python
@neosam@mastodon.social avatar

Source unknown.

bread80,
@bread80@mstdn.social avatar

@neosam Perfect.

bread80, to random
@bread80@mstdn.social avatar

This week I added the Peek() and Poke() intrinsics to the . That means I can now write my first non-trivial program.

I spend this morning fixing a few bugs in the parser and code generator and it's successfully generating the assembler file.

The assembler is choking on a couple of issues with identifiers, and the output code has a couple of bugs to do with parameter parsing and result processing.

Very close to working <g>

A section of the output assembler code.

bread80,
@bread80@mstdn.social avatar

The compiler doesn't have arrays yet, so I'm using pointers to memory and Peek and Poke - hence why they're useful.

I also don't have any kind of memory management. I'm hard coding addresses which I know won't clobber anything.

I have to work around a few other missing features and bugs. It'll be interesting to see the code develop as the compiler develops.

And the same for the code generation. It's still deeply naive with plenty of potential for even basic improvements.

bread80,
@bread80@mstdn.social avatar

Looks like all the known bugs are squashed.

Now onto deployment ... it's a while since I've built for anything other than the emulator/raw binary.

I changed the deployment system after the last time I built for WinApe. And previously doing such builds was clunky. In theory the new deployment system should make this a lot easier.

Dtl, to random
@Dtl@mastodon.social avatar

A thought occurs to me, the covid test extraction buffer splits open the virus particles and causes them to fall apart, effectively killing them.

Therefore, if I replace all my blood with extraction fluid it'll kill off the covid very quickly. There can be no possible downsides to this.

bread80,
@bread80@mstdn.social avatar

@Dtl I venture to suggest that replacing your blood with almost anything will prevent you from catching covid.

bread80, to random
@bread80@mstdn.social avatar

Everyone: Amstrad is back!

Me: That kerning is atrocious.

jonn_blanchard, to random
@jonn_blanchard@retrochat.online avatar

Just, come on: https://www.ebay.co.uk/itm/226016025211

bread80,
@bread80@mstdn.social avatar

@jonn_blanchard There used to be one on listed for £5,000. Possibly the same one, and they’re slowly moving toward reality.

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