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Is anyone working on a new PCB and schematics with Z80, TMS9928A and SN76489? And perhaps a better video output using CXA1645 or similar?

I would definitely buy either naked PCB or assembled board if it was available.

dhau wrote

Is anyone working on a new PCB and schematics with Z80, TMS9928A and SN76489? And perhaps a better video output using CXA1645 or similar?

I would definitely buy either naked PCB or assembled board if it was available.

You could buy the Analogue Nt mini and jailbreak it with the firmware by Kevtris. I have heard that it supports the Master System, SG-1000 (with correct colours) and many more systems.

Pretty sure that's not viable, I really doubt there's enough interest in the SG-1000 to warrant a hardware clone.

I will do something for SC-3000 in future, but not SG-1000.

SC-3000 replica is also very cool! Original hardware is insanely expensive on eBay. I guess if not a replica with original key components (Z80, TMS9918, SN76489) then an FPGA implementation for one of the cheap and widespread boards, like Altera DE1. Probably can borrow liberally from OneChipMSX.

I'll be using original chips, just adding provisions to support both 50 and 60Hz VDPs, adding all mods and tweaks to get best sound and video and whatnot. It'll be my all in one development machine, which is why original parts get used.

How feasible would it be to mod a TMS9918a (and SN76489a) onto an SMS for authentic video? Or even to go the whole way and add in the PPIs and some sort of keyboard? I think the chips are fairly available, and I guess a microcontroller could let you use a USB keyboard, or even emulate the tape signal...

If switching VDPs during operation isn't required then it wouldn't be that hard. PSG is write only so it can pretty much run in parallel all times.

Adding PPI and keyboard is a bit more complicated, extra effort is needed to make controllers play nice. The way controller reading works on SC-3000 is completely incompatible with any controller or dongle that is powered so some sort of bus switching needs to be done instead of GND lifting, and since couple signals are bidirectional on SMS it isn't super straightforward either. It is certainly doable though, and I am very much intrigued by the idea of sticking SMS into the SC-3000 now haha. *todo list is endless already*

Author	Message
dhau Joined: 03 Jul 2005 Posts: 45 Location: Toronto, Canada	SEGA SG-1000 replica? Posted: Tue Mar 07, 2017 9:06 pm
	Is anyone working on a new PCB and schematics with Z80, TMS9928A and SN76489? And perhaps a better video output using CXA1645 or similar? I would definitely buy either naked PCB or assembled board if it was available.

pcfreak324 Joined: 02 Aug 2015 Posts: 19	Posted: Fri Mar 10, 2017 7:51 am
pcfreak324 Joined: 02 Aug 2015 Posts: 19	dhau wrote Is anyone working on a new PCB and schematics with Z80, TMS9928A and SN76489? And perhaps a better video output using CXA1645 or similar? I would definitely buy either naked PCB or assembled board if it was available. You could buy the Analogue Nt mini and jailbreak it with the firmware by Kevtris. I have heard that it supports the Master System, SG-1000 (with correct colours) and many more systems.

ApolloBoy Joined: 30 Jan 2007 Posts: 314 Location: San Jose, CA	Posted: Wed Mar 15, 2017 7:24 am
	Pretty sure that's not viable, I really doubt there's enough interest in the SG-1000 to warrant a hardware clone.

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	Posted: Wed Mar 15, 2017 9:42 am
	I will do something for SC-3000 in future, but not SG-1000.

dhau Joined: 03 Jul 2005 Posts: 45 Location: Toronto, Canada	Posted: Wed Mar 15, 2017 3:50 pm
	SC-3000 replica is also very cool! Original hardware is insanely expensive on eBay. I guess if not a replica with original key components (Z80, TMS9918, SN76489) then an FPGA implementation for one of the cheap and widespread boards, like Altera DE1. Probably can borrow liberally from OneChipMSX.

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	Posted: Wed Mar 15, 2017 5:57 pm
	I'll be using original chips, just adding provisions to support both 50 and 60Hz VDPs, adding all mods and tweaks to get best sound and video and whatnot. It'll be my all in one development machine, which is why original parts get used.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14744 Location: London	Posted: Wed Mar 15, 2017 8:04 pm
	How feasible would it be to mod a TMS9918a (and SN76489a) onto an SMS for authentic video? Or even to go the whole way and add in the PPIs and some sort of keyboard? I think the chips are fairly available, and I guess a microcontroller could let you use a USB keyboard, or even emulate the tape signal...

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	Posted: Thu Mar 16, 2017 7:31 am
	If switching VDPs during operation isn't required then it wouldn't be that hard. PSG is write only so it can pretty much run in parallel all times. Adding PPI and keyboard is a bit more complicated, extra effort is needed to make controllers play nice. The way controller reading works on SC-3000 is completely incompatible with any controller or dongle that is powered so some sort of bus switching needs to be done instead of GND lifting, and since couple signals are bidirectional on SMS it isn't super straightforward either. It is certainly doable though, and I am very much intrigued by the idea of sticking SMS into the SC-3000 now haha. todo list is endless already

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