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JGH is the person to ask. The whole point of the shadow RAM is that it is not normally in the CPU memory map. &3000-&7FFF shadow RAM (known as LYNNE) is available to machine code programs by manipulating the memory map latch (ACCess CONtrol) at &FE34. Details are in the Advanced Reference Manual for...

Could be a dry joint. Could be a poor plug or socket connection. Could be the contacts in the on/off switch. Could be the device that controls the demagnetisation of the screen. Could be a large electrolytic capacitor in the main power section.

Mark

First, just to be clear, LCD TVs may or may not work with unusual signals, but they work differently (being a completely different technology) so will not be damaged by a non-standard signal. Feel free to try anything you like with the signal to these. Any modern-ish CRT TV should also not be damage...

Yeah, I wouldn’t take the horizontal/line frequency down too low. Some 15625Hz CRT monitor’s and most CRT televisions use the line timebase running at 15625Hz to produce various supply rails for other parts of the set. And all generate the EHT voltage from the line output transformer. Most line time...

If you want proper sub-directories, there's only one option...

danielj wrote: ↑

Mon Sep 17, 2018 9:09 pm

Any better?

Only with beer goggles on...

The gotek uses USB by default, but it can use a very small one! (e.g. a Sandisk Ultrafit) :) Thanks, Daniel - List updated - Don't suppose there's a schematic that's black-on-white? See attachments :wink: Note: also included as a zipped file to get around the overzealous forum image compressor. Als...

So 5V at 2A is not uncommon. It may be possible to find a better quality PSU.

Yes, the extra terminal for grounding would be on the signal generator.

Mark

Yes. But in the longer term, you would be better off adding a 4mm green coloured socket or a “grounding” combined screw and 4mm terminal. Another way to make something floating with respect to the mains, is to feed the existing SMPSU via an isolating transformer (230/240V primary, 230/240V secondary...

You may also want to consider Dave’s latest cartridge, the Retro Hardware ARA III - Low Cost Writable ROM Cartridge - For the Electron and Master

Mark

And now breathe out...

Nice

Mark

Following the famous phrase ‘if in doubt add another Pi’ could you put a Pi zero in a box with level shifters etc. and an econet connecter and use this purely to bit bang? It would take in raw econet data and convert it to something that the Pi server could use. It would also take meaningful data f...

See also the links in this post

Mark

Micro Gotek by Zaxon at SellMyRetro
Zaxon’s web site with photos of the connections

Mark

To answer the original question regarding use of the ROM sockets vs. sideways RAM, here is an extract from the Master Service Manual : LK18 plug, made West: Paged ROM/RAM Select. Two position link. When fitted in the West position, this link causes 16Kbyte of RAM to appear in each of the "sideways" ...

Does this system make use of a Drive Ready/Disk Changed (/RDY, pin 34) signal?

Or it’s timed out waiting for another signal from the drive?
Pin 26 /TRK00 Track 0
Pin 8 /INDEX Index

If one of these signals is missing, would this cause these symptoms?

Mark

If the wiring loom for the top head is removed from the connector on the board, that would do it! Alternatively, there could possibly be a link in the logic circuits that select which head to use. Or the input control from the control and data (the 34 way ribbon) cable by be disconnected somewhere. ...

I'd fear for the fidelity of the power supply... Never mind that, imagine the scene in summer: the place stacked out with warm Beebs and other retro gear, everywhere rather toasty with the heat. Hence the air conditioning going at full pelt. Then a Rifa capacitor lets go... Followed by a mass stamp...

As with anything else, after a good visual inspection, the next step is to work out (by testing) what power supply rails are okay and which ones are missing or low. No need to worry about testing the EHT though.

If the tube heater is not glowing, that normally means it has lost it’s supply.

Mark

Colin’s comments remind me that poor quality, or poorly stored tapes sometimes are the cause. For some reason, the friction between the spool(s) and the case increases, hindering the free movement of the spool(s). A hexagon shaped pencil is useful for seeing who difficult a spool is to rotate. I kee...

Any electronic or electrical component that is overheating, being overloaded or self destructing can be the cause of smoke. I recommend that you open it up and carry out a visual inspection by eye (under a good light) looking for any physical trace of the cause of the smoke, such as soot marks, blac...

Tape chewing is normally a mechanical fault with the take-up spool drive running slower than the capsan (the rubber roller near the tape read/write head). Sometimes due to a slipping belt. Also ensure that the tape path and head is clean. And that the capsan rubber roller is slightly grippy and not ...

Are you sure C10 is a tantalum capacitor? It may be another type. Normally film capacitors are used in audio circuitry. Anyway, it's best if you include a 100nF capacitor between the wiper of your variable resistor / pot / preset and pin 3 (the LM386) input to seperate the different DC levels. And t...

You can have the teletext adapter if you want it Colin.

Mark

If no one else wants these, I would like to save them from silicon heaven. The monochrome monitor may be useful for a display for one of the monochrome computers that I own (ZX80, ZX81, Video Genie).

I would prefer to collect at the Leicester ABUG meet-up if that's okay.

Mark

The caps lock and shift lock LEDs are controlled by IC10 (74LS259). IC10 is on the 'slow bus' provided by IC8 (the 'system' 6522 VIA, often a CMOS version in Masters). However, it's more likely that the problem is the wiring or connections between the main board and the keyboard, damaged conductors ...

I have a question for people who've looked at it before. My first thought for doing this was to hook the Pi up to the 5 pins on the Econet jack via some level shifters and have the Pi emulate the clock etc as well as the file server. Looking at the links to past projects it seems like most people i...

Thanks, Dave! Just arrived in Canada, this will be heading into school soon for students to experience old school computing! Best wishes, Paul :D Wow! . . . That was posted on the 16th July :shock: And I claimed compensation for a lost package - the tracking says it's just leaving the UK :lol: I th...

As it can't find the OS ROM either, it looks like it's not looking in the correct folder/directory.

Mark