6502 NOP generator - UK Vintage Radio Repair and Restoration Discussion Forum

ScottishColin · 20th Jun 2022, 10:28 pm

Just found (and ordered) this in case others might need one on future - only £4.80 + P&P.

I wish I knew it existed when I was wrestling with soldering mine.

https://www.laser.com/product_info.p...oducts_id/1981

Colin.

Mark1960 · 21st Jun 2022, 12:12 am

I made a universal NOP generator to test different 40 pin processors, Though I still need to add a clock divider to try it on nmos 6502s and it probably won’t work on Western digital 65C02 as I believe they have cmos input threshold voltages.

Bottom side of the board has 4 of 2x20 pin headers to connect any pin to 5v or 0v, then every pin has a 10k pull up to 5v, and a 1k to a green led down to ground, with pin headers to short any led to ground. Pins will float to between 2.5 and 3v or can be pulled down to 0.5v. Tested so far using cmos and nmos z80s, 8749 and INS8060. A 74hc04 oscillator with a socket to swap in different crystals can be connected to any pin using dupont connector cable but lowest crystal I have is about 1.8 MHz.

Idea was to use this to test a few different micros from my junkbox, but I’ve also used it to check if an 82s131 prom was unprogrammed.

ScottishColin · 22nd Jun 2022, 5:27 pm

Blimey. That sounds like quite a feat.

Got any photos?

Colin.

Quote:

Originally Posted by Mark1960

I made a universal NOP generator to test different 40 pin processors, Though I still need to add a clock divider to try it on nmos 6502s and it probably won’t work on Western digital 65C02 as I believe they have cmos input threshold voltages.

Bottom side of the board has 4 of 2x20 pin headers to connect any pin to 5v or 0v, then every pin has a 10k pull up to 5v, and a 1k to a green led down to ground, with pin headers to short any led to ground. Pins will float to between 2.5 and 3v or can be pulled down to 0.5v. Tested so far using cmos and nmos z80s, 8749 and INS8060. A 74hc04 oscillator with a socket to swap in different crystals can be connected to any pin using dupont connector cable but lowest crystal I have is about 1.8 MHz.

Idea was to use this to test a few different micros from my junkbox, but I’ve also used it to check if an 82s131 prom was unprogrammed.

ajgriff · 22nd Jun 2022, 6:57 pm

Quote:

Originally Posted by ScottishColin

Just found (and ordered) this in case others might need one on future - only £4.80 + P&P.

Just followed the link Colin and the order total came to £6.00 unit price + £1.20 VAT + £3.00 P&P = £10.20. Not saying that's expensive but for some reason it doesn't tally with the figures you quoted. I'm probably doing something daft.

Alan

ScottishColin · 22nd Jun 2022, 8:23 pm

The shipping was a fiver. Also the unit price has gone up since I bought mine.

Colin.

SiriusHardware · 22nd Jun 2022, 10:21 pm

Still a good find and should save the obvious frustration caused by the less than reliable home made ones. When you are trying to fix or trace a fault the last thing you need is to have to fix your test gear before you can go on to fix the fault.

Plus, having a completely dependable NOP generator (...and knowing exactly where it is!) virtually guarantees that you will never need it. Think of it as a form of health insurance for your PET.

ScottishColin · 22nd Jun 2022, 10:44 pm

I think it's one of those small production run things I should buy because it might not be there next time I look.

Colin.

Quote:

Originally Posted by ajgriff

Quote:

Originally Posted by ScottishColin

Just found (and ordered) this in case others might need one on future - only £4.80 + P&P.

Just followed the link Colin and the order total came to £6.00 unit price + £1.20 VAT + £3.00 P&P = £10.20. Not saying that's expensive but for some reason it doesn't tally with the figures you quoted. I'm probably doing something daft.

Alan

Quote:

Originally Posted by SiriusHardware

Still a good find and should save the obvious frustration caused by the less than reliable home made ones. When you are trying to fix or trace a fault the last thing you need is to have to fix your test gear before you can go on to fix the fault.

Plus, having a completely dependable NOP generator (...and knowing exactly where it is!) virtually guarantees that you will never need it. Think of it as a form of health insurance for your PET.

SiriusHardware · 22nd Jun 2022, 10:54 pm

Good point, I have several things like that which I bought because I had no idea how much longer they would be available for.

Mark1960 · 22nd Jun 2022, 11:06 pm

Don’t forget to test it before you need it, otherwise you won’t know if its the tester or the 6502 at fault.

Mark1960 · 23rd Jun 2022, 12:48 am

Attached a few photos of the NOP tester, not sure if the SMT resistors and leds will be clearly visible.

ScottishColin · 23rd Jun 2022, 7:01 am

I can only imagine how to do something like that.

Respect.

Colin.

Quote:

Originally Posted by Mark1960

Attached a few photos of the NOP tester, not sure if the SMT resistors and leds will be clearly visible.

ajgriff · 23rd Jun 2022, 8:39 am

Quote:

Originally Posted by SiriusHardware

Plus, having a completely dependable NOP generator (...and knowing exactly where it is!) virtually guarantees that you will never need it. Think of it as a form of health insurance for your PET.

Joking aside, for anyone also contemplating the added insurance of a ROM/RAM board it's worth noting that both the ROMulator 6502 and the ROMulan PET RAMulator already have selectable NOP functionality built in.

Alan

ScottishColin · 23rd Jun 2022, 10:13 am

Having bought the Tynemouth board with its older testing software and the lack of NOP testing capability, I'm wondering if I would buy different next time.

It works fine for what I need right now I guess, but I'd do more research next time.

Colin.

20th Jun 2022, 10:28 pm	#1
ScottishColin Heptode Join Date: May 2012 Location: Perth, Scotland Posts: 939	6502 NOP generator Just found (and ordered) this in case others might need one on future - only £4.80 + P&P. I wish I knew it existed when I was wrestling with soldering mine. https://www.laser.com/product_info.p...oducts_id/1981 Colin.

21st Jun 2022, 12:12 am	#2
Mark1960 Heptode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 834	Re: 6502 NOP generator I made a universal NOP generator to test different 40 pin processors, Though I still need to add a clock divider to try it on nmos 6502s and it probably won’t work on Western digital 65C02 as I believe they have cmos input threshold voltages. Bottom side of the board has 4 of 2x20 pin headers to connect any pin to 5v or 0v, then every pin has a 10k pull up to 5v, and a 1k to a green led down to ground, with pin headers to short any led to ground. Pins will float to between 2.5 and 3v or can be pulled down to 0.5v. Tested so far using cmos and nmos z80s, 8749 and INS8060. A 74hc04 oscillator with a socket to swap in different crystals can be connected to any pin using dupont connector cable but lowest crystal I have is about 1.8 MHz. Idea was to use this to test a few different micros from my junkbox, but I’ve also used it to check if an 82s131 prom was unprogrammed.

22nd Jun 2022, 8:23 pm	#5
ScottishColin Heptode Join Date: May 2012 Location: Perth, Scotland Posts: 939	Re: 6502 NOP generator The shipping was a fiver. Also the unit price has gone up since I bought mine. Colin.

22nd Jun 2022, 10:21 pm	#6
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 8,630	Re: 6502 NOP generator Still a good find and should save the obvious frustration caused by the less than reliable home made ones. When you are trying to fix or trace a fault the last thing you need is to have to fix your test gear before you can go on to fix the fault. Plus, having a completely dependable NOP generator (...and knowing exactly where it is!) virtually guarantees that you will never need it. Think of it as a form of health insurance for your PET.

22nd Jun 2022, 10:54 pm	#8
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 8,630	Re: 6502 NOP generator Good point, I have several things like that which I bought because I had no idea how much longer they would be available for.

22nd Jun 2022, 11:06 pm	#9
Mark1960 Heptode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 834	Re: 6502 NOP generator Don’t forget to test it before you need it, otherwise you won’t know if its the tester or the 6502 at fault.

23rd Jun 2022, 12:48 am	#10
Mark1960 Heptode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 834	Re: 6502 NOP generator Attached a few photos of the NOP tester, not sure if the SMT resistors and leds will be clearly visible. Attached Thumbnails

23rd Jun 2022, 10:13 am	#13
ScottishColin Heptode Join Date: May 2012 Location: Perth, Scotland Posts: 939	Re: 6502 NOP generator Having bought the Tynemouth board with its older testing software and the lack of NOP testing capability, I'm wondering if I would buy different next time. It works fine for what I need right now I guess, but I'd do more research next time. Colin.