MK14 schematic revisions – Page 9 – UK Vintage Radio Repair and how to get rid of acne scars fast naturally Restoration Discussion Forum

For the SOC VDU, be aware that one of the ics on that – the character generator IC – is quite a specialised IC and may be hard to how to get rid of acne scars fast naturally find now. It was actually an option which did not automatically come how to get rid of acne scars fast naturally with the VDU kit, you had to pay extra for it. It still sort of works without it, but only in dot-matrix (graphics / pixel) mode. If you want to use it in its text / character output mode you’ll need the character generator IC.

If slothie manages to track the VDU connections to the how to get rid of acne scars fast naturally rear edge -and- removes the images from 0200-07FF (a big ask) then there is the possibility to place a ‘ram pack’ in between the MK14 and the original SOC VDU, or just by itself to give the machine a respectable how to get rid of acne scars fast naturally extra 1.5K of RAM.

Even when hooking the VDU into the MK14 in the how to get rid of acne scars fast naturally manner intended there were a few required changed such as how to get rid of acne scars fast naturally track cuts and a change to a 4mhz crystal, so it was quite a destructive process. Mine still bears the scars, even though I have modified it back to near original how to get rid of acne scars fast naturally state, except for the keypad of course.

Yes, an acknowledged weakness of the cassette audio signalling format is how to get rid of acne scars fast naturally that it starts sending significant information immediately – this was addressed in later sinclair machines by sending a how to get rid of acne scars fast naturally long preamble of steady tone to let the recorder AGC how to get rid of acne scars fast naturally settle before starting to send significant data.

I’ve never heard of the interesting HF injection method to how to get rid of acne scars fast naturally pre-adjust the AGC action before but another forum member here how to get rid of acne scars fast naturally (gert?) had the brilliant idea of inverting the data before sending how to get rid of acne scars fast naturally it to the cassette interface so that the signalling is how to get rid of acne scars fast naturally done, not by silence broken by 4ms or 16ms bursts of how to get rid of acne scars fast naturally tone, but by interrupting the otherwise continuous audio tone for either how to get rid of acne scars fast naturally 4ms or 16ms. That would provide a lead-in tone for the recorder to adjust its gain on how to get rid of acne scars fast naturally before any significant information begins to be sent.

I was actually wondering if we could (or should) collect all the links to known sources for MK14 software how to get rid of acne scars fast naturally and hardware projects into a thread of its own, which might also incorporate some discussion about actually programming the how to get rid of acne scars fast naturally machine – there’s a lot of interest in recreating the hardware but how to get rid of acne scars fast naturally people rarely write anything new to run on them (I am as guilty as anyone else).

I’ve been contemplating the idea of setting up a small how to get rid of acne scars fast naturally model railway circuit and trying to do some basic PWM how to get rid of acne scars fast naturally speed control and automatically starting from / stopping at a station – I have some (N gauge) sectional track and a few models to put on it, but no electrically controlled points, so it would have to be quite basic. I think this is the sort of experimental arduino-like hobby control application the MK14 was originally aimed at.

Another, less physically complex and more self contained project might be how to get rid of acne scars fast naturally to connect an alphanumeric LCD display to one or both how to get rid of acne scars fast naturally of the 8154’s I/O ports and recreate the ‘message’ program with the message scrolling on the LCD display with how to get rid of acne scars fast naturally no crippling literary limitations imposed by there being no letters how to get rid of acne scars fast naturally ‘K’, ‘M’,’P’,’Q’, ‘V’, ‘W’, ‘X’, ‘Y’, and ‘Z’.

The alphanumeric LCD display ties in very well with my how to get rid of acne scars fast naturally first intended project which is to port my adaptation (which is 256 Z80 bytes) of an i2c and RTC driver from the next! That is what I am working up to… Now I have actual hardware and a cross assembler.

Other magazines of the time may have something of interest how to get rid of acne scars fast naturally if not directly MK14 then SC/MP (E.G. Elektor who had the designs for a machine based on how to get rid of acne scars fast naturally one if I remember correctly). One I quite fancy having a go at is 2 how to get rid of acne scars fast naturally dimensional version of conway’s game of life described in issue 12 of the how to get rid of acne scars fast naturally 1978 byte:

I have also just been naughty and bought a copy how to get rid of acne scars fast naturally of issue 2 of personal computer world (may 1978) as they are not archived online anywhere. It has a review of the MK14 in it (I noticed as the listing included the contents page) which I will obviously scan – interestingly it is written by nick toop. I think it may be the same person who in how to get rid of acne scars fast naturally PE of april 1979 provides an MK14 diagnostic program written how to get rid of acne scars fast naturally in NIBL BASIC – he is described as working for soc then and is how to get rid of acne scars fast naturally credited as the designer of the VDU board… He has a further article in the dec 1979 PE how to get rid of acne scars fast naturally issue with an output flag multiplexer and falling man animation how to get rid of acne scars fast naturally for the VDU.

The bit that really interested me in the above is how to get rid of acne scars fast naturally the mention of NIBL at soc I wonder if they how to get rid of acne scars fast naturally had somehow put the ROMS (2 off 2316A for £46.90 from greenbank electronics) into the MK14 memory map or were using a more how to get rid of acne scars fast naturally powerful SC/MP system. That started me thinking that if the top four address how to get rid of acne scars fast naturally bits were latched and some mods to the onboard address how to get rid of acne scars fast naturally decoding were done it could appear as another 4K page… Only problem would be the SCIOS reliance on the RAM how to get rid of acne scars fast naturally at FFF appearing to wrap below 000. A future project…

It just seemed to me that it would be ideal how to get rid of acne scars fast naturally to have them match 1:1 so that instead of an edge connector you could how to get rid of acne scars fast naturally solder on a DIN4162 at the top of a patched how to get rid of acne scars fast naturally issue 5 or a slothie v2… In fact rather than doing all the messy patching on how to get rid of acne scars fast naturally martin’s board maybe I will wait for a slothie v2 how to get rid of acne scars fast naturally for myself if he does change the D0-D7 location as it is a right shift of a how to get rid of acne scars fast naturally group that should be possible – the other couple of lines might give him a headache how to get rid of acne scars fast naturally though – especially if we can find a way to get the how to get rid of acne scars fast naturally issue 5 memory decoding and the different RAM chip stuff how to get rid of acne scars fast naturally he has included…

Slothie hope the eye op goes well – understand if you do not make the the above change(s) on your board. It just occurs to me that we effectively have a how to get rid of acne scars fast naturally useful standard connector for VDU and maybe an external RAM/ROM board between the MK14 and the VDU that can how to get rid of acne scars fast naturally be used with anything people like. Indeed you could actually solder a right angled edge connector how to get rid of acne scars fast naturally on the VDU – I cant find where I found this one but, that was done on there so I assume they could how to get rid of acne scars fast naturally just plug it directly onto the MK14!

The VDU manual says that the PADS are present on how to get rid of acne scars fast naturally issue 4 and issue 5 but, you still needed to do your own patching – we still don’t know when the memory decoding improvement happened though unless how to get rid of acne scars fast naturally someone has a reference but, it was on the issue 5 so again if you how to get rid of acne scars fast naturally can put that on it would be authentic – maybe using the original gates and then just a new how to get rid of acne scars fast naturally gate for your memory patch and reset solution… Or not they will be functionally equivalent.

Ordinarily, I would connect the MK14 VDU or my zx81s to how to get rid of acne scars fast naturally a nice little mid-late seventies B/W portable TV that I keep for the purpose, but that is mothballed just now so I dug out how to get rid of acne scars fast naturally my philips CM8524 composite / RGB video monitor and fed that with composite video taken how to get rid of acne scars fast naturally from the input of the VDU’s UHF modulator.

The VDU is of course monochrome, but the philips (colour) monitor has a ‘green’ switch which puts it into a mode where monochrome is how to get rid of acne scars fast naturally displayed as restful green on black instead of white on how to get rid of acne scars fast naturally black. The image is absolutely rock steady – the philips has always been a great monitor for me how to get rid of acne scars fast naturally – I bought it to use with my atari ST in how to get rid of acne scars fast naturally the mid eighties and it is still regularly used with how to get rid of acne scars fast naturally that same atari. I had to replace the power switch once, but that’s all.

Doing this reminded me again just how primitive the VDU how to get rid of acne scars fast naturally is – only 16 characters maximum across, I had to leave a blank line between each line how to get rid of acne scars fast naturally of text because they are insufficiently spaced out otherwise, there are only 64 characters in the character set (no lower case, and only a limited subset of ‘other’ characters available).

Image #2 (displayed in conventional white) is more or less centre justified within the active screen how to get rid of acne scars fast naturally area. It gives a better idea of where the left and how to get rid of acne scars fast naturally right boundaries are and clearly shows that even with the how to get rid of acne scars fast naturally correct 4mhz clock the active screen area is noticeably off-centre towards the left.

One seems to roughly follow the VGA layout the other how to get rid of acne scars fast naturally looks like it is almost the same patch pattern but, totally reversed! The one that seems to be following the VDU for how to get rid of acne scars fast naturally direct connect also has some resistors patching something. Would be nice to work out what is going on how to get rid of acne scars fast naturally there.

I should have credited this link as the source of how to get rid of acne scars fast naturally the VDU board I posted with the edge connector on how to get rid of acne scars fast naturally it. I have just noticed looking at it again I think how to get rid of acne scars fast naturally it carries out the trick I am planning. As you say XOUT should be on the bottom – I suggest on the pin below no A27 as that how to get rid of acne scars fast naturally is unused so would be easy to bend back the how to get rid of acne scars fast naturally pin on the connector and then just bridge the pads…

The other circuit I want to try and may interest how to get rid of acne scars fast naturally others is in the 1980 august issue of practical electronics how to get rid of acne scars fast naturally which is a circuit by anthony D. Love of swansea that uses a 74LS32 to allow bit how to get rid of acne scars fast naturally 6 of the character code to invert individual characters to how to get rid of acne scars fast naturally black on white! Page 48

The would mean that the additional chip you add would how to get rid of acne scars fast naturally be for the alternate memory option – this should also mean only that change has a routing how to get rid of acne scars fast naturally difference to the real MK15 issue V. UTsource have AM2111 at 5.95 each at the moment – they do not show stock levels but seemed happy when how to get rid of acne scars fast naturally I put four in my basket – delivery is slow or steep though…

I have received my two MM80C95N as well which I how to get rid of acne scars fast naturally will try in the VDU when I build it and how to get rid of acne scars fast naturally get it working. One of them certainly works on the keypad IC11 i/f which we are discussing in the other thread. I didn’t think as a CMOS part it would have enough how to get rid of acne scars fast naturally fan out but, maybe the other chips are not being driven as it how to get rid of acne scars fast naturally is a bus… So they need the EN or CS asserted for that. I will study a bit more the VDU schematic how how to get rid of acne scars fast naturally they are used there, as this is at the limits of my electronics knowledge…

Again, some nice information mining there. We’re going to have to make you the official MK14 how to get rid of acne scars fast naturally historian / repository. I remember running the ‘falling man’ animation on my VDU / MK14. That comment by paul robson (-the- paul robson?) is quite new, I only just noticed it myself.

The VDU ‘demo driver’ PCB is a microchip ’44 pin demo PCB’ of the type which was included with pickit3 programmers – the chip on it is a PIC18F452, chosen because it has a ‘PLL’ clock mode which allows it to effectively run at 40mhz how to get rid of acne scars fast naturally with a 10mhz clock crystal. I rigged that up a few years ago now after how to get rid of acne scars fast naturally seeing the VDU PCB sitting unloved in a drawer for how to get rid of acne scars fast naturally decades and finally feeling sorry for it.

In theory you can test the VDU just by programming how to get rid of acne scars fast naturally an eprom with some test text or a test bitmap how to get rid of acne scars fast naturally image and connecting the address, data and RD lines to the appropriate connections on the how to get rid of acne scars fast naturally VDU. (you will need to generate a 4mhz clock for it how to get rid of acne scars fast naturally as well).

Character mode is the easiest to try this with since how to get rid of acne scars fast naturally the relationship of screen ram locations to screen character locations how to get rid of acne scars fast naturally is exactly as you would expect, screen ram location zero is the first (upper left) character on the screen, screen ram location 511 is the lower right character on how to get rid of acne scars fast naturally the screen.

In graphics / bitmap mode the relationship between screen ram locations and pixel how to get rid of acne scars fast naturally locations is not quite as simple as you would expect, I’ll go into that in more detail some other time. There’s a reason why the ‘falling man’ animation scrolls downwards rather than across… I’ll also post the VDU’s reduced ASCII character code set as well, as I don’t know if it is documented anywhere.

I have been meaning for years to do something more how to get rid of acne scars fast naturally than just the static text display with that VDU demo how to get rid of acne scars fast naturally jig – I changed the demo code a couple of days ago how to get rid of acne scars fast naturally to put the VDU into graphics mode for probably the how to get rid of acne scars fast naturally first time since it was attached to the MK14 at how to get rid of acne scars fast naturally least 40 years ago. There appears to be a small problem with my timing how to get rid of acne scars fast naturally in graphics mode as there is some interference / flickering on two of the vertical pixel lines. I’ll have a look at it again if I get how to get rid of acne scars fast naturally time.

One problem is that the VDU takes the RD line how to get rid of acne scars fast naturally low for the whole of the time it takes to how to get rid of acne scars fast naturally read one horizontal line’s worth of text or graphics RAM, so there’s no falling RD edge each time the VDU wants how to get rid of acne scars fast naturally some new data. It just keeps RD low, changes the address it’s sending out to the host RAM, waits a short time for the new data from the how to get rid of acne scars fast naturally RAM to settle and reads the next data in, repeating that until it has read the data for the how to get rid of acne scars fast naturally whole line. Then, RD goes back high.

The (theoretical) advantage of using a PIC to do this is that, in the period outside the time when the VDU is how to get rid of acne scars fast naturally demanding to be fed data, the PIC could spend a bit of time manipulating / animating the screen ram contents, whereas if you use an EPROM to store a test how to get rid of acne scars fast naturally image it will just be that fixed image – although you could store a different text page or bitmap how to get rid of acne scars fast naturally image every 512 bytes in a very big EPROM and how to get rid of acne scars fast naturally run a binary count-up on the remaining address pins, either slowly for a ‘slideshow’ or quickly to do a flicker-book ‘animation’. (my animation skills are definitely not up to that).

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