Changing ULA types on an ADC06

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
Post Reply
User avatar
retroclinic
Posts: 3034
Joined: Thu Jul 03, 2008 1:22 pm
Location: East Riding of Yorkshire
Contact:

Changing ULA types on an ADC06

Post by retroclinic » Thu Sep 05, 2013 5:07 pm

Hi Folks.

Quick Q...On an ADC06 (Internal Master 128 6502 Co-Pro), I've got Issue 2 boards where one is fitted with the CMOS AMI ULA, and another fitted with the Ferranti ULA. The only difference I can see is a 1W resistor fitted at R1 on the Ferranti board for the internal LV regulators.

Is it just a case of removing this resistor to fit the CMOS ULA to the board, or is there another mod that needs to be done that I can't see? I'd like to remove the Ferranti ULA and keep it for a spare for the earlier Co-Pro, as I've got spares of the CMOS ULA, but not the Ferranti.

Thx, Mark.
Image

PhilYoung
Posts: 203
Joined: Sun Jun 12, 2011 4:55 pm
Contact:

Re: Changing ULA types on an ADC06

Post by PhilYoung » Thu Sep 05, 2013 8:58 pm

retroclinic wrote:Hi Folks.

Quick Q...On an ADC06 (Internal Master 128 6502 Co-Pro), I've got Issue 2 boards where one is fitted with the CMOS AMI ULA, and another fitted with the Ferranti ULA. The only difference I can see is a 1W resistor fitted at R1 on the Ferranti board for the internal LV regulators.

Is it just a case of removing this resistor to fit the CMOS ULA to the board, or is there another mod that needs to be done that I can't see? I'd like to remove the Ferranti ULA and keep it for a spare for the earlier Co-Pro, as I've got spares of the CMOS ULA, but not the Ferranti.

Thx, Mark.
I was researching this recently after blowing up a working Internal co-pro (with the Ferranti ULA and 12ohm resistor) - I removed it and re-fitted it with the right-hand connector one pin out. So +5v went where +5v was not meant to go.

I found that there were pictures of the CMOS ULA fitted to boards both with and without the 12ohm R1. See for example:

http://www.8bs.com/see/WatfordCopro_65C102.jpg (with)
http://acorn.chriswhy.co.uk/8bit_Upgrad ... CoPro.html (with)
http://www.beebmaster.co.uk/MSeriesTurbo.html (without)

I concluded that for an internal co-processor it doesn't matter if the 12ohm is fitted since all the +5v lines from the motherboard connector will be always on or off together. From John Kortinks ReTuLa documentation it seems that the restriction is that you can't use a CMOS ULA in an external co-pro without making sure that it is single powered (host and parasite sides from the same source).

Has a circuit diagram of the internal 65C102 co-processor turned up anywhere ?

Cheers,

Phil Young

User avatar
retroclinic
Posts: 3034
Joined: Thu Jul 03, 2008 1:22 pm
Location: East Riding of Yorkshire
Contact:

Re: Changing ULA types on an ADC06

Post by retroclinic » Thu Sep 05, 2013 9:17 pm

Ok thx for that.

Looking on the schem of the external Co-Pro, I can see that link that selects the power to the ULA, but it doesn't seem to be present on the internal one, so that would make sense.

I've not found a schem for the ADC06, no.

Thx, Mark.
Image

PhilYoung
Posts: 203
Joined: Sun Jun 12, 2011 4:55 pm
Contact:

Re: Changing ULA types on an ADC06

Post by PhilYoung » Fri Sep 06, 2013 6:45 am

retroclinic wrote:Ok thx for that.

Looking on the schem of the external Co-Pro, I can see that link that selects the power to the ULA, but it doesn't seem to be present on the internal one, so that would make sense.

I've not found a schem for the ADC06, no.

Thx, Mark.
I think the internal co-pro might be significantly different from the external one, which is why a circuit would be nice. So the ULA powering arrangement isn't the only difference.

From the external co-pro service guide it seems to divide the clock to 250kHz on boot until it has copied the ROM to lower RAM, switched the ROM out of the memory map and then copied it back to RAM just below &FFFF. Then sets the clock back to 3MHz.

On the internal co-pro the crystal is connected straight across XTLI and XTLO, so there can't be any clock division in the same way. I was starting to buzz it out but that is about as far as I got !

Cheers,

Phil Young

tubbyasstoo
Posts: 236
Joined: Wed May 19, 2010 11:40 am

Re: Changing ULA types on an ADC06

Post by tubbyasstoo » Fri Sep 06, 2013 7:08 am

does this mean you have a copro for sale ?

can I express an interest ? :mrgreen:

PhilYoung
Posts: 203
Joined: Sun Jun 12, 2011 4:55 pm
Contact:

Re: Changing ULA types on an ADC06

Post by PhilYoung » Fri Sep 06, 2013 7:50 am

tubbyasstoo wrote:does this mean you have a copro for sale ?

can I express an interest ? :mrgreen:
It's neither working nor for sale.

The DE0/Tubesilencer combination works fine though - and both of these are for sale, but not by me.

Cheers,

Phil Young

User avatar
retroclinic
Posts: 3034
Joined: Thu Jul 03, 2008 1:22 pm
Location: East Riding of Yorkshire
Contact:

Re: Changing ULA types on an ADC06

Post by retroclinic » Fri Sep 06, 2013 8:12 am

tubbyasstoo wrote:does this mean you have a copro for sale ?

can I express an interest ? :mrgreen:
I've got some of the Master internal 6502s yes, but not really looking to sell them at the moment, unless I got a VERY :wink: offer for one.

Thx, Mark.
Image

User avatar
BigEd
Posts: 2837
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: Changing ULA types on an ADC06

Post by BigEd » Thu Jul 14, 2016 6:04 pm

Phil,
did you get anywhere with finding out the circuit of the internal copro, or with debugging or repairing yours? We have a broken one here...

PhilYoung
Posts: 203
Joined: Sun Jun 12, 2011 4:55 pm
Contact:

Re: Changing ULA types on an ADC06

Post by PhilYoung » Thu Jul 14, 2016 8:47 pm

BigEd wrote:Phil,
did you get anywhere with finding out the circuit of the internal copro, or with debugging or repairing yours? We have a broken one here...
No, sorry, no progress with that. If the point is the co-pro rather than the repair, it's probably best to look at the John Kortink plug-in recent version. Or a DE0 nano/tube silencer mounted inside the case. Or a multi-FPGA if there is another run of those.

Cheers,

Phil Young

User avatar
BigEd
Posts: 2837
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: Changing ULA types on an ADC06

Post by BigEd » Thu Jul 14, 2016 8:51 pm

Oh well! Thanks anyway. (The idea is to diagnose and repair the copro, if we can. For a faster copro we have PiTubeDirect, as well as the matchbox!) Still investigating...

User avatar
MartinB
Posts: 5273
Joined: Mon Mar 31, 2008 9:04 pm
Location: Obscurity
Contact:

Re: Changing ULA types on an ADC06

Post by MartinB » Thu Jul 14, 2016 9:03 pm

My Master 128 with internal Acorn Co-Pro is on the bench for my eeprom investigation and I have a two-channel Rigol so if there's anything I can look at that might help inform your problem, just shout up... 8)

User avatar
BigEd
Posts: 2837
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: Changing ULA types on an ADC06

Post by BigEd » Thu Jul 14, 2016 9:10 pm

Thanks for the offer! We have found something remarkable: the SYNC output of the CPU is broken. A second or so after reset it stops pulsing. If we bend the SYNC pin out of the socket, such that the gate it goes into naturally floats high, the copro very nearly works - it works a lot better. But now, in this state, the RDY pulses which stall the CPU only in cycles after SYNC, in order to refresh the DRAM, are now able to stall the CPU any time. Sometimes those pulses happen during a Tube write, and that will duplicate the write, which is going to muck up the data going to the host. And indeed, running CLOCKSP we see a few replicated characters. Running Elite we get some scribbling across the screen followed by a crash.

So, now we know what's happening but not how to fix it. Any sources for an affordable replacement 65C02??

(Sorry, this is a bit of a derail of the thread...)

User avatar
MartinB
Posts: 5273
Joined: Mon Mar 31, 2008 9:04 pm
Location: Obscurity
Contact:

Re: Changing ULA types on an ADC06

Post by MartinB » Thu Jul 14, 2016 9:17 pm

No worries, it'll be there for a good while (and is always accessible anyway) so if anything else crops up, the offer still stands 8)

I don't think I have any spare 65C02's (beyond one for myself), I'll check just in case, but otherwise over to your readers...... :wink:

User avatar
tricky
Posts: 4000
Joined: Tue Jun 21, 2011 8:25 am
Contact:

Re: Changing ULA types on an ADC06

Post by tricky » Thu Jul 14, 2016 10:03 pm

Just noticed this on ebay, not sure if they are any good.
10PC "NEW" G65SC12P-2 40PIN DIP 2MHZ 6502 COMPATIBLE W/O CLOCK
£30+£25 P&P from USA
http://www.ebay.co.uk/itm/10PC-NEW-G65S ... SwrklVDjjz

EDIT: A similar batch of 10 for £30+£10
P&P 10PC "NEW" G65SC102PI-3 40PIN DIP 3MHZ INDUSTRIAL TEMP 6502 COMPATIBLE PROCESSOR

User avatar
hoglet
Posts: 8914
Joined: Sat Oct 13, 2012 6:21 pm
Location: Bristol
Contact:

Re: Changing ULA types on an ADC06

Post by hoglet » Thu Jul 14, 2016 10:13 pm

The misbehaving processor is a R65C102P4, which is different to most of the other 6502s, in that it has an internal oscillator that just needs an external crystal (i.e. no need for two of inverters to make an external oscillator).

As Ed said, the sync output was behaving very strangely, and would vanish completely if freezer spray was applied.

These don't seem very common.

Dave

User avatar
BigEd
Posts: 2837
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: Changing ULA types on an ADC06

Post by BigEd » Fri Jul 15, 2016 12:07 pm

Oops - I said 65C02 and should have said 65C102... it might prove to be possible to adapt a 65C02 to work in the turbo card. Or even a 65816!

Thanks for the pointer tricky - note that we should use P4 parts for 4MHz operation. It seems that CMD's G65SC102P4 can be found on ebay
http://www.ebay.com/sch/i.html?_nkw=G65SC102P4

whereas Rockwell's R65C102P4 product can be found on AliExpress - free postage to UK but not rapid.
http://www.aliexpress.com/wholesale?Sea ... =R65C102P4
(Sellers seem to sell a mix of P2 P3 and P4 parts - not sure if you can specify. If they are modern parts it might be they are all 4MHz capable.)

In all these cases, the parts may or may not be genuine, but for me the important question is whether they work! Buying a lot of 5 or 10 might make sense as a safety precaution.

User avatar
BeebMaster
Posts: 3054
Joined: Sun Aug 02, 2009 4:59 pm
Location: Lost in the BeebVault!
Contact:

Re: Changing ULA types on an ADC06

Post by BeebMaster » Fri Jul 15, 2016 9:14 pm

I'd never taken any notice before as to whether R1 was fitted or not. In addition to the two in the link above, I've a third 65C102 co-processor now, which does have R1 fitted. It has the AMI Tube ULA, but it is socketed unlike the other two. The socket is definitely part of the original manufacture, but I suppose it could possibly be that the ULA is a replacement chip.
Image

User avatar
hoglet
Posts: 8914
Joined: Sat Oct 13, 2012 6:21 pm
Location: Bristol
Contact:

Re: Changing ULA types on an ADC06

Post by hoglet » Fri Jul 15, 2016 9:24 pm

BeebMaster wrote:I'd never taken any notice before as to whether R1 was fitted or not. In addition to the two in the link above, I've a third 65C102 co-processor now, which does have R1 fitted. It has the AMI Tube ULA, but it is socketed unlike the other two. The socket is definitely part of the original manufacture, but I suppose it could possibly be that the ULA is a replacement chip.
Like this one?
http://www.8bs.com/see/65C102_Front.jpg

Dave

User avatar
MartinB
Posts: 5273
Joined: Mon Mar 31, 2008 9:04 pm
Location: Obscurity
Contact:

Re: Changing ULA types on an ADC06

Post by MartinB » Fri Jul 15, 2016 11:14 pm

This is mine for reference....
Co-Pro.JPG

Post Reply