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On my Linux System, I have a short cut (link) set-up to fire up CoolTerm. Then it’s just a case of opening the channel, selecting the file and clicking send

I also use CoolTerm for sending EPROM images to one of my EPROM programmers.

Mark

Things to check (if you have not yet done so):

• Reset lines.
• CPU clock signal okay.
• Control, address and data lines. Both resistance checks when the system is off, and ‘scope checks when it’s on.
• ROM select active.
• ROM okay

Mark

Today I got a tiny bulb in the post, for the power switch of my MDS-230. Nothing out of the ordinary you might think, until you see the size of the box it came in... FullSizeRender.jpg The bulb is about 1.5cm long. Look at that box! No wonder shipping it cost £6 from Germany. Worth it, though.. the...

danielj wrote: ↑

Sat Oct 20, 2018 3:48 pm

- yes, I will, I just need to get the bits in and find some of that magic time stuff!

If you do come across a crate of “magic time stuff”, please let me know... Not got very far reading that thread (that them PCBs relate to) yet

Mark

Does BeebMaster not have an enormous stockpile of Econet modules in the BeebVault?

Although joking aside, yes it’s wise to have the Econet component positions on the PCB .

Mark

Part 2 So ‘Boot-repair’ started to do it’s thing. I answered the questions and entered the terminal commands into a bash terminal. It downloaded some files. Spat out a warning, but finished without any errors. Time to remove the DVD and let the system try to boot from the HDD. At last, Linux booted ...

Not done anything with any 1980s/1990s computers for a while :-( What follows is the slightly shortened (!) version... (no, honestly...) On Tuesday evening, I let my main (Linux) PC do an update. When rebooting, I found it had a very (and nearly useless) command line interface. No, not even ‘bash’. ...

The data sheet that I found looks to give the access time as 200ns.

Mark

I don’t think I have any U256D chips. There are lots of equivalents for 4116 DRAMs though. I have bought some 16k x 4 bit chips by accident in the past when I was not paying attention :oops: I’m sure one day, I will find a use for them... Back to your problem. Is the pin-out the same? Are the U256D ...

To nick a phrase from elsewhere in the computing industry, “where do you want to go today”? Or rather, which market segment do you want to sell to? What do you want a computer for? Games? Educational? Business? Scientific? Accounts? Process control? In the 1980s engineers/inventers/companies came up...

In simple terms, a composite signal that does not include the colour carrier (be it PAL or NTSC) is equivalent to a single colour channel of an analogue RGB signal. So for example, if you have a display device which accepts an analogue RGB input and there is an option for sync on green, you can feed...

There is no quick way of reverse engineering a complex PCB. However, educated guesses and a multimeter on the resistance range can help when dealing with certain chips. Especially if the design of that part of the circuit is the same as, or similar to the chip manufacturers example or typical circui...

RGB TTL (or TTL RGB) uses 5V logic level signals to communicate the eight (additive) primary colours via three circuits (three wires) plus one or two synchronisation signals and a 0V/GND connection. The BBC B, BBC Master and Acorn Electron use this system to connect to suitable Microvic Cub monitors...

C64/C128 output composite video (some output what these days we call S-Video as well). So as long as the monitor has a composite input (or better yet, S-Video or equivalent inputs) it should be possible. Looking at this web page , a monochrome image looks possible. But without a signal converter cir...

If you are getting data errors, they are much more likely with disk images rather than ROM images, simply due to the size. Most people leave unused bytes in EPROMs/EEPROMs as 0xFF. Because that is the value that a byte goes to when a EPROM or EEPROM goes to when erased. So it saves a programmer (a b...

Two things... It’s not a very good “screen protector” if it can’t even keep mould out...! I’m disappointed that the big white power button does not light up... Mark It's the glue that goes mouldy! But you knew that . . . Dave H :D Oi! Someone’s cut a link in the chain that I was yanking! :shock: :l...

Two things...
It’s not a very good “screen protector” if it can’t even keep mould out...!
I’m disappointed that the big white power button does not light up...

Mark

Yes, that is the next step. Freezer spray (or an air duster spay can uses upside down)...

Mark

Yeah, but the system reads the disk to locate that logical position. Sector and track data is stored on the disk as part of the format. The drive is a dumb device (and on soft sectored disks) there is only a single physical index pulse and on some drives, a single “track zero” signal. All the clever...

And don’t forget to enjoy destroying that deathdaptor

The MODE used for start-up is determined by the keyboard links/DIP switches (as are some filing systems options). See this web page . If the “system” 6522 VIA (IC3) is not present, the OS can’t read the keyboard links/DIP switches. Yes, I know that most machines don’t have any links or DIP switches ...

Elminster wrote: ↑

Fri Oct 12, 2018 11:42 am

So the idea is that each diode drops about 0.65Vs?

Wouldnt you traditionally use a zenner to clamp the voltage instead?

Just trying to follow along.

Yes, you could use a 2.7V Zener diode. But how many of us have one spare?

Mark

I suggest for pin 16, to limit the voltage to between 2.4V and 2.8V, connect four 1N4148 (or equivalent) signal diodes in series between pin 16 (first diode anode connection) and a suitable 0V/GND pin (last diode cathode connection). The original resistor stays connected between the Beeb’s +5V pin a...

I would not worry about the input voltages from the Beeb not dropping down after the resistors. It may well be the case that the TV does not load all the inputs to 75 ohms unless it is in RGB input mode. And in any case, it’s highly unlikely that the 5V will do any harm, as (1) the current must be v...

This picture:

Is typical of a TV in SCART composite mode, but with only a RGB signal being fed to it. The visible white elements are simply crosstalk.

Mark

LG TVs (and a lot of other LCD TVs) default to composite video inputs on their SCART inputs (as is normal). Some TVs have a user manual selection control in the menus or via a remote control button. However this does not apply to all modern(-ish) TVs. For these, you have to supply the correct voltag...

MartinB wrote: ↑

Wed Oct 10, 2018 10:11 pm

it would have looked like I was quoting myself!

Never stopped you before

Mark

There is an old thread that may be relevant Additional fora for non Acorn machines? I mainly use forums and websites. Occasionally I dip my feet into Facebook groups. These are some other 8 bit and 16 bit computer forums where I am a member:- ZX80, ZX81 and clones: Sinclair ZX World forums ZX Spectr...

Col does say DFS in his post...
I think he intended that it may show what may be possible on ADFS...

And Colin being a lover of DFS, and, well, shall we say “not too keen” on ADFS, you would not expect him to have a ADFS tool, would you?!

Mark

From the service manual: LK12 Plug, made B (East): CSYNC/Cartridge Machine Detect. Two position link. Position A - This connection to the computer CSYNC line is provided for GENLOCK purposes. Position B - Certain hardware cartridges may need to detect whether they are plugged into a Master Series co...