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Specific flux and % in 0.5mm or 0.381mm solder is less important with hand SMD work if you're loading the iron and using extra flux - because it has all burnt off. I just use extra flux (Amtech and Topnik) and rely on that. The only time the flux in the solder is of use is when I am loading pads - I...

Fixed connector footprint, assembled and ready for steve3000 to confirm it works (I don't have an A5000). Top: Photo0852.jpg Bottom: Photo0849.jpg It should just work because it is simply a layout modification of the working design. Once Steve has had a chance to test I'll release the gerbers. I'll ...

Welcome!

Do you know of any super cheap SWD programmers? Do you mean the Serial Wire Debug for STM32 ARM chips? There are the very cheap (£1.50) dongles which are advertised as ST LInk V2 but aren't (there is github repo with a JTAG firmware for those diry JTAG maybe so you can buy and use those for JTAG in...

Are you already putting the code through a BASIC cruncher? JGH wrote (at least?) one (google mdfs crunch). There are plenty of tips for reducing BASIC code size too - have you been targetting this aggressively already? e.g. every new line costs a CR and two(!) bytes for line number IIRC so : is a cl...

I assume you don't have an Altera USB Blaster or other download cable for Altera/Intel FPGAs? The clone Altera USB blasters work well and cost £2.50 (or £3.70 shipped from the UK). IIRC they are supported by urjtag and/or openocd if the user doesn't want to use the vendor tools. Not worth using a b...

I saw it on eBay. The photos show an FTDI chip. Ready assembled with the DIN plug I don't think it is a bad price. I don't know if that particular FTDI chip will do 76k8 but it very probably will - whether this device works at that speed or not I can not say. So for the money including fees it seems...

I didn't get it to invert (and I can't quite imagine how it would), but I can generate a funny double-peak waveform (consistently) at the switchover 1MHz -> 2MHz if done at just the right time. Attached. (Second peak from left is a double peak.) edit: OK my post descended into edit hell so I have r...

Try changing the clock rate in the ULA fast->slow->fast. You might be able to get the 1MHz CLK to the 6845 to invert if the timing is right.

Different ULA versions might have different behaviour.

https://www.ebay.com/itm/174075785959?ul_noapp=true

Gosh.

Here is a photo of the tested working version. This should work in steve3000's machines now & I will post it to him soon so he can have a try. It still hasn't been tested in an A3020... Photo0826.jpg Once the testing is complete I'll release the Gerbers. I will also make a small batch to order as a ...

I'm not sure you'll need an inverter - they are most useful when the lower bank is faulty and the machine doesn't boot IIRC. i.e. move the fault to the upper bank. Character corruption in mode 7 or graphics corruption in mode 0 should help work out which bit(s) are faulty and therefore which chips a...

The problem remains, though, that where there is a manager ROM, this will be executing from within the &8000 to &BFFF region so a naive attempt to write that manager ROM could page in the 12K of RAM over that ROM causing a crash. This isn't a problem with the Solidisk boards because one register se...

I don't mean it shadows SWR but the address map can go past 0x8000 so can be used as SWR. The 32K block "overlaps" &8000 and is available as a sideways RAM on the 4MEG Solidisk board I have (default is 20KB shadow, 12KB SWR). The manual says you can move the base so it shadows more or less of 0-7fff...

I firmly believe the board pages the main RAM &0000-&7FFF, which the manual also claims: Sounds reasonable. I can't find my original manual so can't look it up. Perhaps I am confusing it with the shadow facility on the Solidisk 2/4Meg boards which do overlap the sideways ROM area and the Watford on...

10+ cycles of the test now and zero errors so that is good. I will clean these boards and send them to Steve3000 next week to confirm they work in his machine. I am confident they will. This testing has been done on an A4000 so it would be good to get some testing on an A3020 & confirm that they (a)...

IanS wrote: ↑

Sat Oct 19, 2019 2:35 pm

And... what is the result?

Only 4 rounds completed so far Ian. We managed quite a few at Cambridge in this machine with the no buffer board so I'm not chicken counting just yet!

Fresh from soldering (I didn't even clean the flux off) A3020 RAM with buffers under test in an A4000.

Booted and detected 4096KB. Now running IanS's large file copy test test.

Yes if the PLD is installed. Without the PLD you need to make J5, J6 and J4 1-2

Have you had comms mode working?

tricky wrote: ↑

Mon Oct 14, 2019 7:56 pm

I'll try some different capture software.

You did set the jumper to the snoop position?

Can you post the BBC BASIC version as plain text please Ed?

It really is that simple.

You need a cable with the edge connector for the floppy and the pins one for the gotek. Set the jumpers for which is drive 0/1. Get some molex extensions/splitter from eBay to get power to both drives. Put it all in a case.

No electronics just some cables and adapters.

Sold to waltermixxx

Matt Godbolt's talk at CppCon 2019 about Compiler Explorer is quite interesting if the internals/behind the scenes of compilers & Compiler Explorer appeal. I use CE with the GCC 6502... sadly op-code highlighting still hasn't been fully implemented. A simple oversight I am sure... https://youtu.be/k...

Since this didn't sell on eBay I fixed it up a bit: I cleaned the keyboard and washed all the keycaps. All the keys work fine now. I fitted it with one of Tricky's SD card readers. I also fitted one of my 32KB sideways RAM modules and a 64KB EEPROM module preloaded with MMFS and SmartSPI. You can ha...

Sorry Chris, I did that and it still doesn't appear as a COM port and the sample D2XX still only identifies it and cannot communicate. Double check the EEPROM contents are still there. I bought some purple boards from aliexpress and the EEPROM chips were faulty so the settings never stuck. Simply s...

You need flux for desolder braid to work well/at all... the cheap stuff from eBay has no flux in. Chemwik etc does and works well straight from the reel. Otherwise get some liquid flux (Topnik is cheap and good) and dip the cheap braid in it & it will magically work so much better! The only other pi...

Issue 7 model B

I did, but I only got around to building it at the weekend. It doesn't appear as a USB port (maybe needs programming). The d2xx sample app finds it but can't send/receive. Would you describe the signals above as normal? Yes you need to program the USB module EEPROM before use. FTProg is on the FTDI...

Did you get on of my FTDI tube sniffers? I can't remember... hoglet's 6502 decode is super useful. I assume you've checked 5v and ground at all the logic chips for connectivity? Without that, if it looks like the CPU is executing from ROM correctly and everything else is a mess then I'd write a test...