Search found 430 matches

by myelin
Fri Mar 16, 2018 8:18 am
Forum: hardware
Topic: Myelin's in-system updateable MegaROM for the BBC Master 128
Replies: 31
Views: 1755

Re: Myelin's in-system updateable MegaROM for the BBC Master 128

crj wrote:Another - though it may be a bit late now - would be to have a buffer between your circuitry and the bus.
I wish! Barely enough space / pin count in my xc9572xl to make the existing board work, let alone buffering the D bus. Time to move up to the 95144 perhaps!
by myelin
Fri Mar 16, 2018 7:33 am
Forum: hardware
Topic: Myelin's in-system updateable MegaROM for the BBC Master 128
Replies: 31
Views: 1755

Re: Myelin's in-system updateable MegaROM for the BBC Master 128

Hmm. What do you mean by "let go" of the data bus? The 6502 has no concept of not accessing memory; every cycle loads or stores something . By "let go of the data bus", I mean I want the D0-7 lines tristated for about 20 seconds. In the Master, you're OK, because the bus from the OS ROM is unidirec...
by myelin
Fri Mar 16, 2018 12:16 am
Forum: hardware
Topic: Myelin's in-system updateable MegaROM for the BBC Master 128
Replies: 31
Views: 1755

Re: Myelin's in-system updateable MegaROM for the BBC Master 128

An update on this project: I have it working reliably in a Master 128, after adding series resistors in the SPI clock and slave select lines, and I've also gotten it working on a Model B, with some modifications. The solution I thought I'd found (mentioned a few posts up) turned out not to be as rel...
by myelin
Wed Mar 14, 2018 10:11 pm
Forum: wanted
Topic: Electron outer box sleeve (or a good scan of!)
Replies: 2
Views: 361

Re: Electron outer box sleeve (or a good scan of!)

I have one at home that I might be able to scan... will update here once I have something :)
by myelin
Wed Mar 14, 2018 5:23 pm
Forum: wanted
Topic: Wanted: case (incl cartridge surround and speaker) and keyboard for Master 128
Replies: 3
Views: 310

Re: Wanted: case (incl cartridge surround and speaker) and keyboard for Master 128

Talking to Mark at Retroclinic about one now :) Sounds like he has some cases in stock that didn't meet the grade for his refurb machines, but should be fine for me!
by myelin
Wed Mar 14, 2018 5:48 am
Forum: wanted
Topic: Wanted: case (incl cartridge surround and speaker) and keyboard for Master 128
Replies: 3
Views: 310

Wanted: case (incl cartridge surround and speaker) and keyboard for Master 128

I have a Master 128 motherboard and a homebrew power supply, and I'd like to turn this into a full machine... is anyone willing to part with a case (including the loose bits -- cartridge surround and speaker) and/or keyboard?
by myelin
Wed Mar 14, 2018 1:02 am
Forum: software: other
Topic: Using fast storage devices as swap / paging space
Replies: 4
Views: 661

Using fast storage devices as swap / paging space

I've been trying to figure out how to practically write utility programs for the BBC/Electron that can be "good citizens", not trampling on working memory (the current BASIC program, filesystem space, etc), without having to execute from sideways RAM or be severely restricted memory-wise, and it occ...
by myelin
Tue Mar 13, 2018 9:59 pm
Forum: development tools
Topic: Request membership of the Stardot organisation on GitHub here
Replies: 53
Views: 4951

Re: Request membership of the Stardot organisation on GitHub here

Hi!

Could I please be added to the Stardot organisation? --> https://github.com/myelin/
by myelin
Tue Mar 13, 2018 6:05 am
Forum: hardware
Topic: Econet Bridge Circuit Diagram
Replies: 7
Views: 1112

Re: Econet Bridge Circuit Diagram

The actual Econet protocol is a subset of what the 68B54 can do; pretty standard half duplex differential serial with bit stuffing. If supporting the 68B54 interface expected by BBC/Master Econet software isn't required, you can do it with a lot less. flynnjs's USB Econet interface got it working us...
by myelin
Mon Mar 12, 2018 6:00 pm
Forum: hardware
Topic: "Minus One" - 3 x cartridge Electron expansion
Replies: 26
Views: 2271

Re: "Minus One" - 3 x cartridge Electron expansion

I had a Plus 3 back then, but I know that is sold long ago. Seems a Plus One should be the way to go to allow some Roms or disk access via the slots, but eBay has none and the pricing on their seems to have gone stupid! I have seen the GoSDC thing, but that seems a tad pricey for a single function ...
by myelin
Mon Mar 12, 2018 5:34 pm
Forum: hardware
Topic: RGB keyboard LEDs?
Replies: 26
Views: 1255

Re: RGB keyboard LEDs?

I try to avoid posting too many "That's really cool!" posts myself to keep the noise levels down, but I can see how it might be discouraging. I completely agree with cmorley on this - I read all sorts of threads on here and think they're cool, even if I wouldn't really want to own one myself (for h...
by myelin
Fri Mar 09, 2018 12:05 am
Forum: software
Topic: POLL: Kickstarter project - Hero: The Realm
Replies: 47
Views: 6732

Re: POLL: Kickstarter project - Hero: The Realm

This forum is generally a super friendly place, but can get a little negative when someone joins and starts marketing a project straight away. More of a small town than big city atmosphere, perhaps ;) Good luck with the project! I don't have any Acorn ARM hardware (any more... used to have an A4000 ...
by myelin
Tue Mar 06, 2018 1:38 am
Forum: hardware
Topic: Acorn's Second Processors and the Tube - what, and why
Replies: 47
Views: 3445

Re: Acorn's Second Processors and the Tube - what, and why

tbh, untill someone makes a vid of this running on a spectrum,(or spec next) I dont think anyone is gonna be convinced. Get some hardware to Hoglet, and I'm sure something will show up in short order :) I need a diagram of the spectrum/pi set up. not a bbc>>z80 setup as existed physically in the 80...
by myelin
Mon Mar 05, 2018 6:23 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

Progress note: the grid spacing on Revaldinho's full size picture is *almost* perfectly regular, but just off enough that some manual calibration is required. I've thrown together a little Processing app to let me draw in grid lines. Once that's done, I'll chop the image up into individual squares a...
by myelin
Mon Mar 05, 2018 1:38 am
Forum: hardware
Topic: HostFS and microcontrollers?
Replies: 48
Views: 3345

Re: HostFS and microcontrollers?

Myelin already started and cracked the timing for the hardware flow control which helped! He mentions sync issues above which are a bit worrying - I added in an interrupt routine to help track CTS changes which might fix this. It seems fine on one large transfer... not tested much else yet. It's go...
by myelin
Sun Mar 04, 2018 8:24 am
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

That's good news... all the ones I've seen are in plastic DIP packages; I didn't realize there were ceramic versions also.
by myelin
Sun Mar 04, 2018 4:11 am
Forum: acorn atom
Topic: Crazy idea? Downgrade Electron to an Atom? Possible?
Replies: 19
Views: 985

Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Back to the original premise... I’m curious how *many* ULA-less Electrons there are out in the wild. Does everyone here have one? I have two working Elks and would be curious to try making a ULA replacement, or trying out Dave H’s board, but I don’t want to touch my working ULAs; anyone got a broken...
by myelin
Sat Mar 03, 2018 9:44 pm
Forum: hardware
Topic: Mega Games Cartridge (MGC) MK II Hardware Development
Replies: 30
Views: 1571

Re: Mega Games Cartridge (MGC) MK II Hardware Development

I’ll take care of the Model C, to be wired internally into the Elk!
by myelin
Sat Mar 03, 2018 6:43 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

If anyone's breaking out the acid to dissolve some chips, might I suggest that the MSI gate arrays (the CF3xxx chips) in the Master 128, plus the serial and video ULA from the Model B, would be very interesting to see, and are, as far as I can tell, unphotographed so far... I've worked in image proc...
by myelin
Sat Mar 03, 2018 4:06 am
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

My copy of his book just arrived :)

The Elk ULA (12C021M) uses the same cells as the Spectrum/ZX81 ones (6Cxxx). My intention is to extract the wiring pattern from revaldinho’s photo, and use Hoglet’s code to turn it into a netlist that can be converted into authoritative “source code” for the chip.
by myelin
Fri Mar 02, 2018 10:37 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

:D :D I could definitely do something useful if there's a full size version of similar quality to that close up!
by myelin
Fri Mar 02, 2018 10:34 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

I wonder if the off-grid routing was a manual exception to get something tricky to fit in... because almost everything else zig zags all over the place when it needs to go on a diagonal. I feel that the transcription process here will be mostly automatic with a ton of manual cleanup afterwards. Fing...
by myelin
Fri Mar 02, 2018 10:04 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 45
Views: 3344

Re: Electron ULA Schematics

I just came across this picture on Flickr , a die shot of the 12C012M ULA! If you click on it and view the highest resolution picture, it looks like there's *just* enough resolution to view the entire metallization pattern, which should hopefully allow us to extract the exact circuit, using Hoglet's...
by myelin
Thu Mar 01, 2018 8:05 pm
Forum: introduce yourself
Topic: Hello from California, possibly Exile's biggest fan!
Replies: 25
Views: 1253

Re: Hello from California, possibly Exile's biggest fan!

Welcome! I’m the SF-dwelling Electron hacker Thomas Harte mentioned a few posts back. (Thomas, I got your email, unfortunately right after I’d landed back in SF after a week in NYC!)
by myelin
Mon Feb 26, 2018 12:39 am
Forum: hardware
Topic: Pi Zero Super Interface
Replies: 23
Views: 1559

Re: Pi Zero Super Interface

Kicking myself for not bidding more on the one Master Compact I’ve seen on eBay now; this sounds like fun :)
by myelin
Thu Feb 22, 2018 7:06 pm
Forum: hardware
Topic: HostFS and microcontrollers?
Replies: 48
Views: 3345

Re: HostFS and microcontrollers?

I'm interested in this too, especially since I saw my Arduino MKR1000 mounts nicely onto a BBC micro ashtray (assuming the cover got pushed in during the 80s... like happened on mine). I was wondering if you could have MicroPython running on the MCU host, or given it has WiFi onboard, serving some ...
by myelin
Thu Feb 22, 2018 2:26 am
Forum: general
Topic: led light range
Replies: 3
Views: 408

Re: led light range

Probably not on topic for the 8-bit hardware board... maybe move this to miscellaneous < off-topic?
by myelin
Wed Feb 21, 2018 9:32 pm
Forum: hardware
Topic: Pi Zero Super Interface
Replies: 23
Views: 1559

Re: Pi Zero Super Interface

jgharston wrote:there's no "SHEILA" signal on the edge connector.
Doesn't the Master Compact edge connector bring out the full address bus, like the edge connector on the Electron? If I haven't misread the schematic, it looks like it should be easy enough to generate the "SHEILA" signal from A8-15.
by myelin
Wed Feb 21, 2018 7:55 pm
Forum: hardware
Topic: Pi Zero Super Interface
Replies: 23
Views: 1559

Re: Pi Zero Super Interface

Does a Pi in a cartridge interface similarly make sense - or maybe that's already been considered? There's my two Pi-on-a-cartridge projects -- http://myelin.nz/acorn/elktube and http://myelin.nz/acorn/fx2tube -- which should be a good place to start for anyone intending on prototyping something al...
by myelin
Wed Feb 21, 2018 6:37 pm
Forum: hardware
Topic: Myelin's in-system updateable MegaROM for the BBC Master 128
Replies: 31
Views: 1755

Re: Myelin's in-system updateable MegaROM for the BBC Master 128

Good news! Last night I got it all working. It looks like there must have been some kind of grounding issue once I plugged the board into an actual Master 128; I solved it with some tweaks to the Verilog that made it a bit more noise tolerant. Now I can read and write the flash while the machine is ...