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Old 7th May 2022, 11:52 pm   #61
SiriusHardware
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Default Re: Yet another MK14 tape interface (ESP32).

That's a PCB version we don't really know much about, in fact we don't even have a name or nickname for those replica PCBs yet. It's interesting that they have made reset available on the keypad edge connector - the issue VI has that as well. It's a sensible move which SOC should have thought of themselves. If it is a close clone of the issue V I would imagine it has the track side contact 'fingers' for the rear edge connector but these will not be wired to anything so if you want to connect anything which requires the address, data, read write signals etc you will need to wire those contacts on the the edge connector to the appropriate signal lines yourself.

I believe that PCB also has a position for a discreet link or resistor to tie sense-A to 0V if the board is running the 'New' OS. I take it must be using the OS PROMs from your original MK14 for now, or maybe you managed to source a set.

I don't know if you are a Youtube man but it would be nice to see a demo of that fast load system of yours running. It probably holds the current MK14 record for speedloading.
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Old 8th May 2022, 11:48 am   #62
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Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by SiriusHardware View Post
That's a PCB version we don't really know much about, in fact we don't even have a name or nickname for those replica PCBs yet. It's interesting that they have made reset available on the keypad edge connector - the issue VI has that as well. It's a sensible move which SOC should have thought of themselves.
I am sure that is the one from Chris a member here (of Softy fame)... so should be "the Oddy" maybe?

http://www.theoddys.com/acorn/Replic...lica_mk14.html
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Old 8th May 2022, 4:11 pm   #63
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Default Re: Yet another MK14 tape interface (ESP32).

Hi Coolsnaz2, I noticed a couple of resistors not fitted yet in your replica. You might want to check their function before powering up to avoid any unexpected problems. Maybe you are still collecting a few parts to complete the build.
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Old 8th May 2022, 7:41 pm   #64
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Default Re: Yet another MK14 tape interface (ESP32).

Thanks for all the comments, photos show original and replica side by side.
R16 is only required for use with VDU board.

Timbucas, I thing you are right, it is "the Oddy" board, very please with it.

Also link to YouTube showing demo of Fast Load process.

https://youtu.be/BemPyaoNqb4

Please be gentle, my first YouTube video.

I also did a price comparison, £50 in 1979 is equivalent to £270 in 2022, and that's approximately how much the replica cost to build. Most parts sourced from Ebay or Amazon.
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Old 8th May 2022, 8:19 pm   #65
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Default Re: Yet another MK14 tape interface (ESP32).

Nice one coolsnaz2 - that is really simple and fast. I must investigate one of those devices I think they would be useful for my Triton project as well.

What keypad do you have connected to the Oddy? It always seem to be out of shot... or is that on purpose.

Interesting price comparison - like you I had worked out the vintage machines seem to cost about the same to build today as they did then in real terms.

The video repeats by the way - let's hope this is the start of an MK14 channel to watch.
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Old 9th May 2022, 12:03 am   #66
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Default Re: Yet another MK14 tape interface (ESP32).

The 'Oddy' it is, then.

Good video! I actually laughed out loud when I saw how fast it is, there's really no sense of it taking any time at all - entering the load address now takes considerably longer than loading the code does. I would say it would be well worth trying to get that code into a pair of custom PROMs once you are completely happy with it.

The only thing I can think of which would work faster is something Slothie mooted a while ago, and that is a direct-connected DMA uploader which forces the SC/MP off the bus by asserting NENIN, takes over the buses and fires the code directly into the RAM parallel byte by parallel byte. But this synchronous-serial uploader of yours is already so fast that it doesn't really need to get any faster.

If you think back to how it was back in the day: Manual entry of code, even if you really hit your rhythm something like Moon Landing would take about 10 minutes to enter and then, unless you were exceptionally brave you had to run back through all the entered code to make sure there were no errors because if there were the program could run wild and wipe itself out. And then when you switched the power off... it was all gone.

The cassette interface was a step forward, pretty vital in fact, but it ran at the speed of mud, around 4 characters per second. Now we have gone from that to this, where you are loading code in no significant time at all.

P.S. - Nice landing...
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Old 9th May 2022, 5:37 am   #67
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Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by SiriusHardware View Post
The only thing I can think of which would work faster is something Slothie mooted a while ago, and that is a direct-connected DMA uploader which forces the SC/MP off the bus by asserting NENIN, takes over the buses and fires the code directly into the RAM parallel byte by parallel byte. But this synchronous-serial uploader of yours is already so fast that it doesn't really need to get any faster.
.
The only real difference that the DMA approach would have is that you could do it in reverse - I.E. suck the memory contents out of the MK14 and save it. This would only have value if you were actively developing programs on the MK14, and that's not really the way anyone is likely to do it these days other than as some kind of challenge!
The uploaders are the best way, given that anyone sane programming their MK14 is going to want to use an assembler, however rudimentary.

I like this project, the M5 is a very neat device... Its an interesting approach too.
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Old 9th May 2022, 6:21 am   #68
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Default Re: Yet another MK14 tape interface (ESP32).

The thought of anyone sane programming an MK14 certainly gave me a good laugh, I think we are all insane and its just a matter of degree.

Someone was offering a set of proms on ebay for serial loading an MK14 but it doesn’t seem to be still available. I think that prom set did not function as a monitor, but it was quite a while ago and I might not be remembering correctly.

I think you mentioned in an earlier post that you almost had it down to a size that would fit in the proms as a replacement for the cassette interface in the version 2 proms, were you able to make any progress on that?
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Old 9th May 2022, 8:49 am   #69
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Default Re: Yet another MK14 tape interface (ESP32).

I remember that, it supported Intel Hex serial download into the machine which has merit in terms of doing away with the need to enter the load address, but in order to do that a lot of the original user-interface code had to be discarded and I don't think it tried to checksum the received code because it would have needed too much additional code to do that. Development of the code would be entirely off-machine.

I assume it left enough of the monitor in place so that the 'OS' routines, 7-segment lookup table etc which many of the sample programs depended on were still in place.
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Old 9th May 2022, 5:10 pm   #70
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Default Re: Yet another MK14 tape interface (ESP32).

My current version of the synchronous-serial upload program is 95 bytes not 82 bytes as previously stated, so will not fit into the existing ROM. The current version has the load address, length and execution address incorporated.

I am currently happy to leave the sync load program in RAM and accept it takes 25 seconds to load, It’s nice to remember how long programs used to take to load, and I would like to keep the replica as close to the original as possible. But saying all that it would be nice to add an additional 1.5k of RAM between 0200 and 06FF.

Mark1960, thanks for the Aliexpress link, I need to get a Red Reset button, it wouldn’t be a MK14 without the Red Button.

Timbucus, the best place to get M5StickC is from thepihut, currently £20 plus P&P (09/05/2022). You may also need to purchase a lead. The keypad is from my original MK14 made 40 years ago, components from RS, photos attached.
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Old 9th May 2022, 6:10 pm   #71
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Default Re: Yet another MK14 tape interface (ESP32).

Well, an idea for you - if you are going to map additional memory into the memory hole anyway, it doesn't all have to be RAM.

You could make 0600-07FF (for example) (E)(EP)ROM rather than RAM and put your fast loader code in that. Just type 0600 GO to invoke the fast loader. That leaves the original OS entirely intact for nostalgia purposes but adds the convenience of speed loading.
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Old 9th May 2022, 8:29 pm   #72
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Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by coolsnaz2 View Post
Mark1960, thanks for the Aliexpress link, I need to get a Red Reset button, it wouldn’t be a MK14 without the Red Button.
Note that the link I posted was for a 10mm high switch, the original MK14 switches on my issue IV were 12.5 mm high square buttons. I have a grey 15mm high switch on my Slothie replica so I thought the lower red one would be slightly better.
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Old 9th May 2022, 8:37 pm   #73
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Default Re: Yet another MK14 tape interface (ESP32).

On my Slothie issue VI replica I went for an all-black look, so black that it goes into stealth mode in bad light. If it's not already turned on, I can't find it. Even the reset switch is black, although the one on my issue 2 is the original red of course.

The 'Oddy' looks good in black as well. I may just possibly have a spare original-square-shape red switch like Mark is talking about - I kept one somewhere intending to use it on the issue VI, but didn't. If you have trouble finding one I can try to dig it out.
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Old 10th May 2022, 8:05 am   #74
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Default Re: Yet another MK14 tape interface (ESP32).

If the current incarnation of your fast loader uses files with the load address and execution address embedded then I guess you are specially preparing the files for use with this uploader, maybe the first four bytes of the file are Load address High, Load Address Low, Execution Address High, Execution Address Low, then the fifth byte onwards is the data, something like that?
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Old 10th May 2022, 4:12 pm   #75
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Default Re: Yet another MK14 tape interface (ESP32).

SirusHardware

I have changed my mind about the colour of the switch, maybe it should be black, because it's not an original.

Attached photo shows Moon_Landing tab from Arduino IDE. First two bytes are load address, followed by 1 byte of file size, and execution address is the last two Bytes, (Execution address -1).

Currently synchronous-serial upload program (Fast Loader) will only run in Ram, so I will need to make some changes before committing to ROM.

Your idea that additional memory does not have to be all RAM also makes a lot of sense. Extra 512 Bytes of ROM at 0200, and extra 1024 Bytes of Ram at 0400. All I need know is someone to design a board that plugs into CPU socket with additional ROM and RAM. But it doesn't make sense doing this unless there is demand from the wider MK14 community.
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Old 10th May 2022, 6:00 pm   #76
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Default Re: Yet another MK14 tape interface (ESP32).

I'm afraid it's time we (myself included) mastered KICAD or some other PCB design software so we can get boards made to order - very cheap nowadays to get a small batch of PCBs made in China.

If you wire all the bus and control lines to the rear underside contacts on the 'Oddy' just as you did on your original issue V, that will give you the option of knocking something up on veroboard and plugging it into the rear edge.

Attached, images of the original offboard memory expansion which I made to a circuit design by Slothie. It was built on a 'bridge' board made to go between the issue VI and my original Science Of Cambridge MK14 VDU.

I basically put two identical bits of Veroboard plain surface to plain surface, copper sides outwards, and slid the pins of the 32-way edge connector on over the edge and soldered them. The DIN connector on the outer end matches the one on the original VDU and also on OrtonView, Karen Orton's hardware VDU emulator. Most of the tracks pass straight through from one connector to the other, so the memory expansion is mounted on a copper-upwards square of veroboard which is placed plain side down on the copper side of the underside of the 'Bridge' board. The images should make it clearer. The flying plug-in leads on the top side of the 'bridge' are for programming the states of the VDU control signals.

On this particular version the area 0200 to 07FF is populated only with RAM but you could use something like a 74138 address decoder + RAM IC + EPROM and choose the RAM / ROM split according to your needs.

If you are pondering the wider appeal of your fast loading system I think there would be some interest in a version resident in the PROMs but that is easy for me to say since I'm not the one who would have to try to make it fit.
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Old 10th May 2022, 8:56 pm   #77
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Default Re: Yet another MK14 tape interface (ESP32).

I’ve been using a free limited version of Eagle 7.6 for a few years now for z80 projects. Tried Kicad a couple of times but found the workflow very clumsy compared to Eagle, not sure if its been improved in the last year. Not sure if Eagle still allow a limited home use version, the license is now bundled with mechanical CAD and I think far too expensive for hobby use.

I’ve not had much time lately due to work, but hoping to get more spare time in the next few weeks.

I built an adapter on protoboard to plug into the 8060 socket with battery backed 512kx8 ram, using 74hct163 to latch A12 to A15, maps 32k of ram in 2k chunks into each 4k page, so thats 0000-07FF, 1000-17FF etc. selectable links so /WE connected to /RD with proms fitted, then remove proms and change the links and run the monitor from ram. Was planning to add an FT245 or 6402 to bootstrap the code by sending instructions to the 8060. 6402 is probably more in keeping with the 8060.
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Old 11th May 2022, 7:30 pm   #78
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Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by Mark1960 View Post
Quote:
Originally Posted by coolsnaz2 View Post
Mark1960, thanks for the Aliexpress link, I need to get a Red Reset button, it wouldn’t be a MK14 without the Red Button.
Note that the link I posted was for a 10mm high switch, the original MK14 switches on my issue IV were 12.5 mm high square buttons. I have a grey 15mm high switch on my Slothie replica so I thought the lower red one would be slightly better.
I was able to get the square top type in white or a red one with the taller round button, So I used the red round one. I think the square top type were supposed to have click-on caps that could be bought in a number of colours and styles, but I haven't seen those available anywhere for years.

Edit: If you're searching on shops or part suppliers, the buttons are in the "D60" range, made by C & K among others, so sometimes "D60 Pushbutton" brings up results once you wade through the lists of Audi window swiiches. I got by white ones from eBay, the red ones from Rapid Electronics (They don't seem to have them now though) and I think I've seen them on RS components in the recent past. It looks like we're trying to find new old stock at this point.....

Last edited by Slothie; 11th May 2022 at 7:40 pm. Reason: Part numbers
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Old 18th Jun 2022, 9:06 pm   #79
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Default Re: Yet another MK14 tape interface (ESP32).

Hi All

Finally got Fast Sync Loader into EEPROM, and working.

Using 28C16 with only 512 bytes exposed at 0200 to MK14, and additional 1k Ram at 0400. Circuit currently on vero board see attached, not very pretty. Board plugs into my existing VDU socket on my back plane. Fast Loader uses 81 of the 512 exposed bytes, so room for more programs. I have also put a copy of the MK14 OS in the EEPROM, so in theory I could expose address 0000, and remove ROMS from MK14, this is unlikely as I like to leave MK14 as original as possible. I used an Arduino Nano to program the 28C16.

The new memory board has been tested on both original and replica MK14.
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Old 19th Jun 2022, 10:41 am   #80
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Default Re: Yet another MK14 tape interface (ESP32).

Well done that is good news and a great addition to the system. Easily simulated by us all RAM expansion people as well to test software that would benefit from being in ROM.
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