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Old 17th May 2021, 9:21 pm   #81
SiriusHardware
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Default Re: Early EPROM programmer.

Quote:
I haven't found the paperwork yet for the softy 2 I picked up last visit
This is clearly an additional, seemingly complete unit, maybe even in its original postal box. If so it may be possible to date it from the post date stamp, if it is readable. The original receipt might even be in there.
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Old 17th May 2021, 9:28 pm   #82
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Default Re: Early EPROM programmer.

Itís another one. Manual is stapled and looks original and in b/w.
Hereís a taster.
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Old 17th May 2021, 9:31 pm   #83
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Default Re: Early EPROM programmer.

Lovely, that circuit diagram looks really crisp.
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Old 17th May 2021, 9:45 pm   #84
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Default Re: Early EPROM programmer.

Yes, just beat me to posting an extract of the schematic from that earlier photo (Now attached)
- Where I could see it was actually for the Softy-2 and confirmed my thoughts on the PSU and that the programming voltage unregulated input voltage was +30Vdc.
And they've used the same pin numbers on the DIN socket that I had (I later read that the DIN standard didn't actually include pin numbers, which is why they are often missing form views of these / are often mirrored. But the whole DIN system ended-up a bit of a failure, due to many manufacturers using it for things it wasn't originally intended for inc. stereo audio!)

It's even more unusual to find two of these rarer black-cased (early?) ones.
But if it turns-out that the first one is missing the PSU etc., then rather useful to have some originals to hand.
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Old 17th May 2021, 10:05 pm   #85
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Default Re: Early EPROM programmer.

Quote:
Originally Posted by onewatt View Post
It’s another one. Manual is stapled and looks original and in b/w.
Here’s a taster.
And here's the individual pages extracted and rotated etc. from that one, as well.
- Although, unfortunately, it seems the forum had compressed the image for that one. So although the schematic is now complete it's actually not as readable as the earlier (partial, happened to be in-shot) one, I'd extracted an image from in previous post.
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Old 17th May 2021, 10:20 pm   #86
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Default Re: Early EPROM programmer.

The 'Low' input voltage which feeds the regulator (TR5 and associated) is perhaps higher than I might have guessed it would be, my guess would be around 8V-9V. The reverse / overvoltage protection diode for that supply input (DZ4) is 18V, a bit more headroom than I would have expected but maybe that just shows that the 'low' input supply is unregulated, as an unregulated supply which is nominally 9V on full load could easily knock out 13V-14V when lightly loaded.
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Old 17th May 2021, 10:30 pm   #87
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Default Re: Early EPROM programmer.

Quote:
Originally Posted by ortek_service View Post
Yes, just beat me to posting an extract of the schematic from that earlier photo (Now attached)
- Where I could see it was actually for the Softy-2 and confirmed my thoughts on the PSU and that the programming voltage unregulated input voltage was +30Vdc.
>>
>>
And here's the Vpp Programming-supply regulator - Where, as I'd presumed, they had used a 78L05 regulator 'jacked-up' with a 20V zener (which they shorted-out with a transistor, to set output back to +5V for Vpp in read-mode)
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Old 17th May 2021, 10:45 pm   #88
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Default Re: Early EPROM programmer.

Quote:
Originally Posted by SiriusHardware View Post
The 'Low' input voltage which feeds the regulator (TR5 and associated) is perhaps higher than I might have guessed it would be, my guess would be around 8V-9V. The reverse / overvoltage protection diode for that supply input (DZ4) is 18V, a bit more headroom than I would have expected but maybe that just shows that the 'low' input supply is unregulated, as an unregulated supply which is nominally 9V on full load could easily knock out 13V-14V when lightly loaded.
What voltage did you see for the Unregulated voltage input to the 5V regulator?
- I couldn't quite read it, as it was just of-shot of the original hi-res photo that had captured most of this.

And full version was too Low-Res. to read
- I couldn't tell if it was +5V4 or +5?V 4A (In which case regulator wouldn't do much, more of a limiter).

I can't see the point of using a LDO discrete-transistor regulator circuit, rather than a (nearly 3V dropout) 7805, if they were going to use 9V (even though many computers of that era did this). Unless they needed > 1A current of 7805 (and 2A / 3A etc. variants hadn't seemed to have been made back then).
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Old 18th May 2021, 7:08 am   #89
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Default Re: Early EPROM programmer.

I thought maybe around 8-9V, based on a compromise between excessive volts drop across the 5V regulator and the need to have a bit of overhead on the input so the regulator can always regulate. It may be a low-drop regulator but not intentionally so. But then why is the input protection diode >= 18V? Maybe to guard against accidental connection of the +30V supply to that supply input terminal.

It's fun to speculate on all this, but when onewatt comes back maybe he will be kind enough to measure the PSU voltages.
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Old 18th May 2021, 7:58 am   #90
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Default Re: Early EPROM programmer.

Well the input-supply to the 5V regulator shouldn't really need much over-voltage protection as it inherently regulates to the desired voltage. And it may well withstand 30V into it - Although power dissipation in TR5 could be an issue!
However, no doubt the 30V supply wouldn't source enough current, and would collapse under the main 5V rail's current, as 30V current only needs to be enough for Vpp requirement and will be limited to < 100mA by the regulator IC in the 25V/5V Vpp reg circuit..

A small 18V zener isn't really going to provide much in the way of over voltage (or reverse-polarity) protection, although it might take out some transients (but doesn't really seem the ideal part to choose for this).

If they didn't need low-dropout, I would have expected them to just use the classic NPN series-pass circuit arrangement (or a 7805). But I think a low dropout regulator was necessary to minimise the power dissipation in TR5 as there's only a rather-small heatsink on it (And on a previous unit's photo, there wasn't one at all, unless someone had removed it).

It will be interesting to see if there''s any labels on the PSU with its output voltages / current etc. Although it looked a bit basic.
Or maybe more info in the manual etc. So may not need to actually measure it.

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Old 18th May 2021, 8:37 am   #91
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Default Re: Early EPROM programmer.

This is quite exciting uncovering a pristine Softy-2 with manuals, the hope that we can get some archived documentation, and downloads of the PROM and EPROM contents. May also be a help in working out some information for hte Softy-1.
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Old 18th May 2021, 10:00 am   #92
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Default Re: Early EPROM programmer.

I'd expect the 74S287 Character Generator PROM to be the same as that for the same one on the Softy-1 - as the video circuitry doesn't really appear to have been changed much from that.
In fact, from looking at pictures of the Softy-2 in the past, and now most of the circuitry that can be seen, it does seem to be mostly the same as the Softy-1 - just with twice as much RAM and the power supply circuitry changed for (simplier) single-rail supplies.
And the firmware may also not be that much different, just needing to handle the larger memory / slight-changes to connections of the larger EPROM's.

But getting copies of all that would still be good, given the rarity of this for the S2 so far. Although reading the PROM may be more tricky, without a PROM programmer etc. that supports it / using an Arduino etc. to write some software to readout contents.
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Old 18th May 2021, 12:02 pm   #93
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Default Re: Early EPROM programmer.

There is some ready-baked Arduino PROM reader software lying around here somewhere, it would just need minor changes to read the 287. In any case onewatt seems to be a device programmer connoisseur so I would not be at all surprised if he has a programmer / reader which can read BPROMs. If not, there may be one waiting to be discovered in that hoard.

I'm not sure onewatt would be prepared to disturb the 40-year old pristine soldering on the character BPROM ...as it seems to be soldered in, in the first example... to read it out for us. Maybe the one in the second example is socketed?
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Old 18th May 2021, 5:58 pm   #94
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Default Re: Early EPROM programmer.

As the prom is a character generator its not going to be readable in circuit by the softy itself. Its unlikely to be socketed in any production unit, unless socketed during repair, and probably not reasonable to ask someone to remove the part for copying.

Is it possible to read the content with a logic analyser and exercise the softy to try and cover all possible address inputs?
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Old 19th May 2021, 12:26 am   #95
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Default Re: Early EPROM programmer.

Yes, on the photo of the Softy-2 PCB that have been posted recently on this thread / some that were originally attached in a post on the Softy-1 thread, its IC7 74S287 PROM IC is directly soldered in - Like most of the IC's, other than the most-expensive (generally larger pins) CPU, PIA, EPROM & the 2114 SRAM's (but not the 2102).

However, the connections to IC7 on the the partial Softy-2 schematic I'd extracted, can be seen to connect exactly to the same other IC's that the original Softy-1's IC9 (74S287 256x4bit PROM) were connected to, with A7 tied-low, so only lower 128 locations are used.
And with A6..A4 for the video vertical scanning (8) rows select, that leaves just 16 Characters (Hex-digits), selected by A3..A0 to produce the 4bit data outputs - Which are selected in turn by the video horizontal-scanning to form the 4 columns for each character.

So I doubt there was much scope / need for changing the 8x4 matrix character font for these 16 characters - From Softy-1's shown here: http://www.theoddys.com/acorn/PROMs%...racter_rom.txt

- produced from PROM code, by (with comments) this Python script: http://www.theoddys.com/acorn/PROMs%...TY%201/Font.py

With the Softy-1 PROM's code on the main page for it: http://www.theoddys.com/acorn/PROMs%...1/softy_1.html


Whilst the Softy 1 (and most-likely 2) couldn't directly-set all the address lines on the PROM or read its data outputs back, whenever the unit displays 0..F it will go through all input combinations. So could attach a DIL test-clip to the IC and feed into a logic analyser / a microcontroller's GPIO inputs to dump the outputted contents all 128 locations.
But I think all you'd do is get the same contents, and screenshots of the display compared to a Softy-1 should also show this.

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Old 19th May 2021, 10:37 am   #96
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Default Re: Early EPROM programmer.

😂 connoisseur! I donít want to give anyone the wrong impression! My programming ability is limited to a binary crib sheet which allows me to convert to hex and install in the right location to get my controller doing what I want it to. You guys are the connoisseurĎs, Iím just learning and like early tech!
Vy Bst
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Old 19th May 2021, 5:02 pm   #97
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Default Re: Early EPROM programmer.

Just astoundingly lucky, then.

As you may have gathered we will be happy to hoover up any information you would be kind enough to provide as and when when you get a chance - copies of the code in the two programmed devices would also be a major plus but, while the EPROM is in a socket and should be easy to read out with any other EPROM programmer you may have access to, the smaller BPROM which contains the character set would have to be removed in order to back up the code and we don't imagine you would want to do that to something which is in pristine original condition with no solder rework ever done on it.

I like Owen's idea of hanging a logic analyser on the BPROM and using it to capture the data being output from every possible address in the BPROM - in the absence of a logic analyser, maybe one of the faster general microprocessor toys such as the Pi Pico could be used to 'watch' the PROM buses to capture the data being output for one occurrence of every possible address. level converters would be needed, yes, and given that the BPROM is being used in a very high-speed application, the capture tool would have to be able to run even faster.

It would be a handy tool to have, as it could also reconstruct the content of PROMs programmed as custom address decoders and potentially other programmed ICs such as GALs.
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Old 19th May 2021, 6:58 pm   #98
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Default Re: Early EPROM programmer.

Maybe a bit of luck in there somewhere!

I'll see about powering them both up and see if they work First, and if they do, will look at removing the bprom from the original one that's not quite as pristine.

out of interest, there were 6 other programmers in the stash. an ART, 2 x Stagg pp28's, an elan E2A & E2 although those look the same, and an other that I can't rem.

By Bst

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Old 19th May 2021, 7:10 pm   #99
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Default Re: Early EPROM programmer.

ART as in ART-EPP2? Aluminium enclosure?

If so, I used to have one of those. I may still have the support software which is for DOS, although it will run OK in a 'DOS COMMAND PROMPT' window under windows as late as 98SE - if I remember correctly that one is serial-connected (RS232, 25-way)

This website here

http://matthieu.benoit.free.fr/

has a good archive of support software for many old programmers, especially the STAGs and, I think, your ELANs as well - they are not sorted in any particular order so do a CTRL-F while on the page and search for the model of interest.

All of the ones you mention are likely to have or need DOS software and will require either a serial or parallel port (usually only one of those, not both) on the host PC to connect to the programmer.
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Old 19th May 2021, 7:22 pm   #100
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Default Re: Early EPROM programmer.

Yes, ally enclosure for the ART and I think I found that site when I was looking for info.
Iím hoping the pcís appear with some software or just the foftware eventually, but itís 2 days into the clearance with probably 3 to 4 more required.......and thatís not allowing time to sort stuff.
Itís a bit of a nightmare. I recon weíve shifted about 2tons of gear so far.
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