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Old 23rd Oct 2021, 5:49 pm   #1
Phil__G
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Default The PICL V2 - a development of Karen's 2007 original

First published in 2007 as a simple, dedicated National Industrial Basic Language computer, Karen's original project has evolved to the point where it really deserves a “Version 2 “ title, if only to encourage early adopters to revisit this fascinating design.

Rather than list the changes, here's a full specification:
1200 baud terminal interface via CH340G USB (for Teraterm etc)
Full and accurate emulation of a 4Mhz SC/MP in a PIC16F877 using Karens cycle-perfect firmware plus omitted instructions
8k bytes of non-volatile static RAM, retaining programs and data during power-off
4k bytes of ROM containing the original National Semiconductors NIBL basic interpreter from 1976
1k Machine-code monitor typical of the period – Modify, List, Display, Hexload, Registers, Go (run) etc
4 controllable output lines with LEDs and interface strip
2 controllable input lines with buttons
Hex-loader reads standard Intel hex files into memory via the terminal (ie Teraterm 'File, Send')
Standalone mode, running without a terminal connected, maybe on a powerbank battery.
Cheap, sub 3” square PCB with just two chips
Crystal-clock equates to a precise 4mhz SC/MP II operation

This is probably the simplest possible SC/MP machine, comprising only of the processor and a memory chip, but its resident monitor and BASIC interpreter make this an ideal introductory project for anyone with an interest in the SC/MP and its applications.

Sincere thanks are due mainly to the late Karen Orton, a gifted and generous engineer whos projects have inspired all of us.
Karens perfect SC/MP emulation on a PIC chip is a fantastic achievement in itself and I credit the whole of this PICLV2 project to Karen, she'd probably have done all this anyway

The files and a PICLV2 document are on http://philg.uk
Here's a video:

https://www.youtube.com/watch?v=d4PSkEpVwAE

Cheers
Phil
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Old 23rd Oct 2021, 11:16 pm   #2
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

There are no changes to the PCB and upgrading is simply a matter of swapping the RAM chip, updating the PIC software and loading the SC/MP monitor.
KB+ commands:
Intel hexloader, Txxxx = type memory, Mxxxx = modify memory,
Dxxxx = display memory, Lxxxx = list memory (opcode-formatted),
Gxxxx = goto program, R = display registers,
N = enter NIBL basic interpreter, Help is '?'.
It has other software bits & bobs such as breakpoint handling, register set & examine and a neat inline-print routine.
The Intel hexloader will directly accept the output of SBASM or AS, etc.
With SBASM use ".tf myfile.hex,int,32" in the source header.
V2 has a stand-alone mode where SC/MP machine-code programs can be run without a terminal connected, using (say) a power-bank phone charger. With its two sense inputs, four flag outputs, and program retention during power-down, it can be a simple standalone controller! Doc & files here: http://www.mccrash-racing.co.uk/philg/picl/picl.htm
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Old 24th Oct 2021, 2:06 pm   #3
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Default Re: The PICL V2 - a development of Karens 2007 original

Phil,

This is brilliant just watched the Video to present the project and as you say I am sure Karen would have got around to this minimal machine update to the PICL at some point. She always presented PAGE2 as what would have been needed on a full 16K type NIBL machine as a 'home computer'.

As NIBL was intended as an industrial control language the whole 'little unit' approach makes an ideal 1979/1980 achievable equivalent of an Arduino using modern components so who knows with the current chip shortage we may need these to run our Boilers and home projects!
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Old 24th Oct 2021, 11:54 pm   #4
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Default Re: The PICL V2 - a development of Karens 2007 original

As a spectator only, I nevertheless salute your fine work on this, Phil, and I am sure Karen would have been delighted to see this project of hers taken up and taken on with such boundless enthusiasm.
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Old 25th Oct 2021, 12:44 am   #5
Mark1960
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Default Re: The PICL V2 - a development of Karens 2007 original

Phil, as you have been digging quite deeply into Karen’s scmp emulation code, do you know if there might be any possibility of implementing the NENIN function, possibly using interupts to avoid changing the instruction cycle times. I don’t care about NENOUT or BUSRQ, just considering using NENIN to boot the PIC off the bus. I’ve been thinking for a while now of making an adapter to plug Karen’s PIC code into one of Slothie’s issue VI boards and if I ever get round to trying that, it would be good to still use an orton view.
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Old 25th Oct 2021, 2:06 am   #6
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

Hi Mark, I cant promise any results but I will have a look at it
Just ordered another batch of pcbs from JLC should anyone want to build a PICL ​
Cheers
Phil
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Old 25th Oct 2021, 2:33 am   #7
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Default Re: The PICL V2 - a development of Karens 2007 original

I’m interested in getting one of your PICL boards. I’m planning a trip to the uk for the holidays, so could probably give you a uk address to send one.
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Old 25th Oct 2021, 1:55 pm   #8
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

Email me with the full postal address Mark & I'll send one as soon as the new batch arrives, maybe a couple of weeks, I avoided the cheapskate postage option this time
рhіlg@tаlk21.соm (retype, dont copy)
We can discuss your nenin idea offline too until its sorted one way or the other
Cheers
Phil
PS this silicon shortage is becoming a problem, if anyone is thinking about building a PICL I would start looking for the PIC16F877 and an 8k x 8 NVRAM now!
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Old 10th Nov 2021, 2:28 pm   #9
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Default Re: The PICL V2 - a development of Karens 2007 original

A few people have mentioned difficulties finding the NVRAM chips, so this is a pointer to availability which I hope the mods will permit given the current silicon shortage.
RS & Farnell have hundreds in stock, almost any of their 'bytewide' 8k x 8 NVRAM will suffice, it doesnt have to be the M48Z08 or DS1225AD in particular, 'bytewide's are all pretty much equivalent.
Even the 'Bytewide' 32k x 8 ones can be used if you ground pin 1 (an unused address line) (see pic)

I've also found a reliable supplier of compatible F-RAM NVRAMs which is a type that doesnt use a lithium battery - the seller has described them as "battery eliminators" which is why I didnt find them earlier!
My PICLV2 has been soak-testing continuously for over a week now with one of these installed, and its perfect. They have a longer retention, they're cheaper and he has plenty of stock.
Again, in the spirit of helping constructors during the silicon-shortage circumstances I hope the mods will allow me to say that its available you-know-where if you search for "6264 NVRAM Battery Eliminator".
I hope this encourages anyone who fancies a PICLV2 but has been put-off by availability problems. PCBs at cost, non profit.
Cheers
Phil
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Old 27th Nov 2021, 1:51 pm   #10
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Default Re: The PICL V2 - a development of Karens 2007 original

Just a quick note to say that I've updated the PICLV2 document on http://philg.uk to include FRAM and other memory options, plus a couple of typos corrected.
Cheers
Phil
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Old 10th Jan 2022, 3:18 pm   #11
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

Tony posted a video of his PICLV2 some time ago, but I only just noticed that he used a PIC16F877A so that has answered a question!
https://www.youtube.com/watch?v=53FRggVh2Fc
Cheers
Phil
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Old 10th Jan 2022, 3:45 pm   #12
Mark1960
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Default Re: The PICL V2 - a development of Karens 2007 original

Hi Phil,
I have the board you sent me, back in Canada now, looks good, hopefully I can get it assembled this week. I’ll need to test with a different usb serial adapter but shouldn’t be a problem.

Mark
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Old 17th Jan 2022, 3:45 am   #13
Michael - K8LH
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Default Re: The PICL V2 - a development of Karens 2007 original

Hi Phil and group:

Would I be stepping on anyone's toes if I try my hand at a new 2-layer NIBL/PICL PCB and project design? 2-layer boards are less expensive at JLCPCB but I'd also like to use a newer, less expensive PIC ($2.43 for an '18877 vs $7.43 for an '877A). Some hardware and firmware changes will be required and the new 16F18877 device can be programmed using an Arduino Uno or Nano.

Stay safe. Cheerful regards, Mike
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Old 17th Jan 2022, 5:07 pm   #14
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

That would be fine by me Mike, of course - although I thought the boards were very reasonably priced from JLC (I gave most of them away!) If Karen's pals here are ok with it then go for it! It is Karens project, always will be.
I always regard my own builds as one-offs for my own education & entertainment, its hugely gratifying if anyone else shows an interest!
I'm looking forward to seeing your project!
Cheers
Phil
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Old 17th Jan 2022, 6:32 pm   #15
Timbucus
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Default Re: The PICL V2 - a development of Karens 2007 original

I think the more the merrier especially if there is now a US contingent as well growing the project... as I said before I am sure Karen would be humbled, honoured and pleased that there was growing interest.
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Old 17th Jan 2022, 9:30 pm   #16
Michael - K8LH
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Default Re: The PICL V2 - a development of Karens 2007 original

Quote:
Originally Posted by Phil__G View Post
I thought the boards were very reasonably priced from JLC (I gave most of them away!)
When I checked your 4-layer PICL PCB on JLCPCB during the weekend the price was $8. Just now I checked again and the price is $2 again. I'm puzzled.

Cheerful regards, Mike
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Old 17th Jan 2022, 11:19 pm   #17
SiriusHardware
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Default Re: The PICL V2 - a development of Karens 2007 original

I can't claim to have been a friend of Karen's as we never 'met' anywhere except here and I knew next to nothing about her personally, but my impression with respect to her projects was that she made them freely available and she never attempted to make any money out of them herself.

The only 'rule', if there is one, is that any associated hardware (PCBs, etc) should ideally be on a not-for profit basis, although it could be argued that a board design represents time and effort expended by the board designer, whose artwork it is.
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Old 18th Jan 2022, 12:06 am   #18
Mark1960
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Default Re: The PICL V2 - a development of Karens 2007 original

Quote:
Originally Posted by Michael - K8LH View Post
When I checked your 4-layer PICL PCB on JLCPCB during the weekend the price was $8. Just now I checked again and the price is $2 again. I'm puzzled.

Cheerful regards, Mike
Hi Mike,

Did you have any other boards in your cart when it gave the $8 quote? Or maybe you were not logged in when it gave $2 again?

Jlcpcb gives special price only on the first design in your cart.

Mark
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Old 18th Jan 2022, 2:11 am   #19
Phil__G
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Default Re: The PICL V2 - a development of Karens 2007 original

The colour (!) of the boards can make a huge difference, and the cheapest colour frequently changes presumably according to stock levels of particular coloured board. Always flip through the colour options to find the best price!
My last batch of 10 PICL's was £27 delivered, when you look at their beautifully made boards, £2.70 seems a steal!

The Jeff Tranter Z80 boards were £1.70 each, and my single-channel emulation encoder was £21 for 100 !!!
How far have we come since domestic rows over ferric chloride stained carpets ?

Last edited by Phil__G; 18th Jan 2022 at 2:31 am.
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Old 18th Jan 2022, 8:57 am   #20
Michael - K8LH
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Default Re: The PICL V2 - a development of Karens 2007 original

Thank you for the comments.

I went back to JLCPCB to order a set of Phil's 4-layer boards and the price is $8 again. Curious, yes, no?

I am aware that the special $2 price is for the first board and I don't have anything in my shopping cart. Green or black solder mask doesn't make a difference but there is an additional $18 charge if I want red.

Please note that I will provide Gerbers and modified firmware free of charge if I create an updated PICL-NIBL project.

Mike
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