Tiny SC/MP system !!!

[Realtime]

Very nice. So the 4K ROM on #111 is write protected NVRAM, but can be writable for OS updates if the jumper is moved to its other position. I assume the SCIOS is permanently write protected.

With all that ram available, I think it’s time to resurrect MK14 monster maze

[Mark1960]

Would the GAL be able to select a fixed page when nENIN is held high? This might avoid the 3k page limit mentioned in #111.

[Phil__G]

Originally Posted by coolsnaz2

... still learning what the GAL can do.

actually the 22v10 can also do tristate but you have to declare pin 13 as /oe

[coolsnaz2]

Another update on my MK14-NV board.

As Mark suggested I have intercepted the NRDS and NWDS going between the daughter board and the main MK14 board, this has allowed me to remove the need for the fly leads.

And as Phil suggested I am using the tristate feature of the GAL22V10 to generate NRDS and NWDS for the MK14 board.

I am currently waiting for a second batch of boards to be delivered with the modifications included, but have produced a video showing the board in action.

https://www.youtube.com/watch?v=S8MWvlWic5o

[SiriusHardware]

Good video, for several reasons

-Demonstrates a level of usability that we could only have dreamed of in the late 1970s

-Short demos of many of the high-end MK14 software titles which have been created recently

-Showcases PiView, especially its colour capability.

Keep up the good work!

[SiriusHardware]

Also, first time I've seen one of the cherry-switch-equipped "issue VII" PCBs in use.

[ortek_service]

Thanks for the update on you now having this working OK on a (modified) original board.

I'd be interested in the schematic & GAL22V10 changes, to try on mine as I still need to connect it to an MK14
- after being busy looking into upgrading the MGH8060 to all the capabilities of the MGH8060GAL with its GAL22V10 (but should be able to do virtually all that does on a GAL18V10 as Tx Inverter is external to it on the MGH8060, so freeing-up some more I/O pins).

I do need to re-write the ROM-images in the DS1845Y, as whilst checking these, I discovered the Dataman 48Pro(+) / the last version (v3.56) of the control software to support it has a rather major bug in that it can't often (read?) / write even the first line of hex correctly with odd interaction between the initial bytes. But it does seem to work if all bytes have the same value So I image the cut-down MemPro version will also be affected.
Whereas the original Dataman48(LV/XP) (as well as TL866) does seem to work OK.

[Mark1960]

Does anyone have a link or a copy of hex file for NIBL located at 0000h set for 2400 or 4800 baud?

[Phil__G]

Hi Mark, yes NIBL at 2400 baud with bit7 fixed etc is in the KO2019 zip file:
SCMPemu24P.zip
This is real, raw NIBL not the PICL version with the serial I/O done by the PIC. The source & listing is there too.

I tried 4800 but GECO was very tight, and it needed silly-long Teraterm delays so it was no faster overall than 2400, I decided to go 9600, ditch the bit-by-bit echo (which is only necessary at the very slow 110 baud) and do the echo by simply calling putc after each getch. Then I got distracted by the FT245 and didnt get finished

The 2400 version linked above works perfectly, I also did a version of the Toolkit for it, thats also included in the KO2019 build "SCMPemu24P.zip" but you may want to relocate it.
Theres BASYS and a disassembler in there too, both of which have a fast-loader, 2400 binary, no delays. All this should work on any 4Mhz, 32k NIBL computer.
https://www.mccrash-racing.co.uk/philg/picl/picl.htm#k2019

[ortek_service]

Originally Posted by coolsnaz2

Another update on my MK14-NV board.

As Mark suggested I have intercepted the NRDS and NWDS going between the daughter board and the main MK14 board, this has allowed me to remove the need for the fly leads.

And as Phil suggested I am using the tristate feature of the GAL22V10 to generate NRDS and NWDS for the MK14 board.

I am currently waiting for a second batch of boards to be delivered with the modifications included, but have produced a video showing the board in action.

https://www.youtube.com/watch?v=S8MWvlWic5o

Originally Posted by ortek_service

Thanks for the update on you now having this working OK on a (modified) original board.

I'd be interested in the schematic & GAL22V10 changes, to try on mine as I still need to connect it to an MK14
>>

I do need to re-write the ROM-images in the DS1845Y, as whilst checking these, I discovered the Dataman 48Pro(+) / the last version (v3.56) of the control software to support it has a rather major bug
>>

I've now received the updated GAL files, to implement the NRDS and NWDS intercepting to avoid the need for the extra flying from Ian M (coolsnaz2). And also the instructions to update the original Issue 1 board to implement this / the 'MK14-WRA' GAL files.

As well as the latest Issue 3 PCB + schematic, with these mods incorporated - plus 'PROTECT' re-connected to GAL (that the I/O pin was originally required to be re-purposed by the mods, with NVRAM A16 'bank' now being linked direct to free up GAL pins for that).
So this issue 3 board requires slightly-different 'MK14-WRD' (With 8154 fitted to MK14) / 'MK14-WRE' (No 8154 fitted to MK14) GAL files.

And have now tried these in my MK14 replica:
- Both the latest Issue 3 and the original issue 1 + track cuts & mod wires (+ SC/MP socket & header swapped-over, to minimise these) booted-up OK on the MK14, once I'd got the right bank etc links setting (I can't recall if I duplicated SCIOS into upper bank of NVRAM)

Although I need to do some further investigation on the latest Issue 3 one I'd assembled, as when pressing 'Mem' to advance through memory (I wish it had a fast auto-repeat on this), it randomly jumps to 2xxxh etc memory address, with 1FF etc displayed on Right-side (rather than expected 00 - FF).
I've not spotted any obvious dodgy joints / loose connections so far.

Whereas the original Issue 1 board with the same NWDS / NRDS mods & updated GAL for this, advances beyond 0200h OK, with no sudden jumps.

[Mark1960]

Thanks Phil, does this copy of NIBL have txd inverted?

I think somethings not quite right in my hardware. It was running ok as ram extension on an MK14 replica, but not when standalone with NIBL in rom. TXD is held low, but I think this is because NIBL is not running. Quick check with a multimeter didn’t find anything obvious so I need to get the scope on it later today if I get time.

[Phil__G]

Originally Posted by Mark1960

Thanks Phil, does this copy of NIBL have txd inverted?

Its standard NIBL Mark so yes, tx is inverted as usual, so Flag0 will need inverting before feeding the FTDI - in other words Flag0 has a standing low with async-serial bits pulsing high - upside-down compared to a UART - as NIBL has always been

In the KO2019 I did the inversion within the STAT emulation which is external to NIBL in the same way as a physical inverter is.

Cheers
Phil

[Mark1960]

Thanks again, I now have NIBL running.

Pin15 on CH340 shorted to Pin16 to invert RXD input to CH340.

Problem was due to trying to allow too many options for ROM. I’m using SST39SF040 because I have a few and these are easier to reprogram than uv erasable, but i laid out the board to allow 28 pin ROM or battery backed RAM. Only 4K of the SST39SF040 is used, but offset to 24000h. I also had A15 connected to pin 31 same as 32 pin sram, but this is write enable on the SST39SF040 and needs to be held high.

PCB is crowded, 74HCT193 and 74LS156 underneath the 8060. 1024x8 sram under the SST39SF040, MAX818L in SOP8 on the solderside below the battery backup for the sram. I don’t have clip for the battery yet, not enough space for CR2032 so left space for CR1025.

I’ll try and get a copy of life running as a stress test before building a version to fit in a case without the header pins for mounting on MK14 replica and without the stacked sockets.

[Phil__G]

I'm not familiar with the SST39SF040 so downloaded the datasheet - its amazing what you can get for three quid now! 512k x8, in (almost) standard jedec bytewide format. Amazing.

[coolsnaz2]

The attached photos and schematics show the updated MK14-NV boards, issue II and Issue III.

Issue II has been created by RealTime with the additional components required to make the board into a standalone SCMP system with 2 x 64k NVSRAM. The board can also be configured for the MK14 by updating the GAL accordingly.

The Issue III board has been created to replace the Issue I board, and the need for the board modifications required to implement the RDS/WDS changes. This board is designed to be used only with the MK14.

[Phil__G]

...a follow-up to post #100, I've now bought these, a quid each, and have one set to 21v and another set to 25v with a switch between them. Its a 3-position and so does Off/21/25 volts on vpp.
https://www.amazon.co.uk/dp/B07RNBJK5F?psc=1&ref=ppx_yo2ov_dt_b_product_details

They're both powered by the TL866 USB lead via a Y-splitter lead:

You could modify the pot to give both switched voltages from one boost reg but at £1 each?

It all works well together, very compact, saves lugging the bench PSU and fills in a few gaps in the TL866 options

[ortek_service]

Originally Posted by Phil__G

...a follow-up to post #100, I've now bought these, a quid each, and have one set to 21v and another set to 25v with a switch between them. Its a 3-position and so does Off/21/25 volts on vpp.
https://www.amazon.co.uk/dp/B07RNBJK5F?psc=1&ref=ppx_yo2ov_dt_b_product_details
>>
>>

Thanks for the info on the cheap Boost Converters.
I presume that if operating these close to min. 2Vin, then they might struggle to get near 28Vout / 2A 'max' output current with that boost ratio due to a max. power limit.

I bought a similar LM2596 Adjustable DC-DC Power Supply Module (for £1.35 with free delivery from China off eBay - although back in 2012 when everything from there was often free delivery and no VAT) - but a Step Down one.
I've mainly been using fixed output voltage (switched-capacitor?) DC-DC converter PCB-Mount modules that whilst smaller, are fairly expensive (especially as you go to 3W and above versions), but Digikey etc do sell much-cheaper brands (Mornsun? etc.) that look to have the same spec's as the usual XP-Power / Murata (ex-Newport / C&D Tech) ones.

Originally Posted by Phil__G

>>
>>
They're both powered by the TL866 USB lead via a Y-splitter lead:
>>
>>

Although that particular one only seem to split the power to one connector (and data to the other), from its description (unless that wasn't quite correct).
However, it seems those ones are sold out, and ones that do split the power to both connectors (kind of the inverse of the power-combiner leads for powering HDD's from Laptop etc 2x USB Ports) are advertised amongst similar items, below it, but at twice the price / the cost of 6 of the boost converters!

[Phil__G]

Hi Owen, the Y-splitter is a data-through plug & socket (like a short usb extension) with the power tapped off - I cut off the connector from the power tap and wired the 5v pos & neg directly to the boost converters.
Then the data plug goes to the PC, data socket takes the TL866 USB lead, and the power tap is wired directly to the boost regs, so they run from 5v (not 2v!)
It all works perfectly

[ortek_service]

Thanks for the info on it.
It wasn't clear that the 'Data' socket also included power (So it's really a straight-through fully wired to a standard USB socket for the 'Data' one)
- It would be a bit odd to not have power on the same USB socket as the Data-lines, being as many USB devices will only work with a VBUS power-rail provided by Host etc. to power it / for it to detect.
And so rather than a true 'Splitter', it's more of a 'Power' Tap / 'T' piece.

Yes, USB will provide around 5V to the DC-DC Boost Converter. But I noted they were spec'd to run down to 2V so I wondered how well they worked if ran off a supply that low (eg a couple of AA Cells when rather flat)

[Phil__G]

I can try that Owen, I've a few spares, maybe tomorrow