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PostPosted: Sun Nov 15, 2009 9:02 pm 
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Hi folks - thought it about time I had a go at fixing the old CBM 3016! It's basically totally dead outwards (no video & no timing signals at the video connector hence blank monitor & no EHT). The 6502 shows clock in/out but theres no IRQ. There is address & data bus activity but I haven't had a thorough check yet as I need to get the schem's printed out! Would a dead 4116 cause the above symptoms, or should I concentrate elsewhere?
Cheers for any help!
Pete (UK)


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PostPosted: Mon Nov 16, 2009 9:50 pm 
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I recommend checking all the pins of the ROM and RAM to see if they have a valid signal, and make sure none of them are stuck.

I would pay particular attention to the chip selects.

The last 6502 board I fixed had a bad LS145. I found it by checking all the chip selects of all the ROM and RAM with a logic probe, and the ROM chip select didn't seem to be triggered as often as it should. So, I desoldered it from the board and stuck it in a solderless breadboard for testing, and sure enough, it didn't decode properly. I stuck a socket in the board and put in a new LS145, and it booted up and ran perfectly.


Toshi


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PostPosted: Mon Nov 16, 2009 11:09 pm 
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Thanks for the tips! I'll be having a proper look tomorrow night & report back how it goes :)

Pete


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PostPosted: Tue Nov 17, 2009 5:49 am 
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v8pete wrote:
Hi folks - thought it about time I had a go at fixing the old CBM 3016!

Not to point out the obvious, but did you verify that the power supply is producing a strong 5 volts. That machine is full of old logic that can be fairly power hungry. I recall from my days of fiddling with Commodore hardware that power supplies seemed to be problem children (especially the C-64's black brick). Also, be sure to 'scope the clock signal to make sure it looks like a square wave and not like a milquetoast with sloped shoulders. :D

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PostPosted: Tue Nov 17, 2009 9:55 pm 
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All now sorted! Firstly we had a dead 74S74 in the video/clock gen circuitry - one of the d-types had a Q output but Q-bar was stuck high. Replacing this restored some video - half a raster with wrong characters and weird patterning. The next fault was a dead 2114 video ram chip - no output on one of the data lines. Replaced this and hey presto ### COMMODORE BASIC #### appeard on the screen! Keyboard needs a good clean as only a handful of keys work reliably, but that's for another day :) God, this thing looks soo ancient - like something from another time zone, which basically it is !!

Cheers!
Pete


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PostPosted: Wed Nov 18, 2009 5:30 am 
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Congrats!

Did you diagnose it with a logic probe?

Toshi


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PostPosted: Wed Nov 18, 2009 6:32 am 
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v8pete wrote:
All now sorted!

Great! Another silicon relic brought back to life. Good job.

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Firstly we had a dead 74S74...

74S' logic. Now there's some ancient silicon. Real power-eaters. You almost need your own substation to run the thing. :D

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God, this thing looks soo ancient - like something from another time zone, which basically it is !!

That's because it is ancient, literally from the last century. :)

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PostPosted: Wed Nov 18, 2009 3:40 pm 
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Agreed. Way back working on the old arcade game Sky Shark (was the manufacturer back then), sprites were controlled from a clocking 74S74. A little heat bomb. Failed rather regularly. One factor I think was a wierd design which was a 4 layer board and any line pulled up did NOT go through a pullup resistor but was directly tied to +5 volts...

Good times

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PostPosted: Wed Nov 18, 2009 7:01 pm 
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Nightmaretony wrote:
One factor I think was a wierd (sic) design which was a 4 layer board and any line pulled up did NOT go through a pullup resistor but was directly tied to +5 volts...

Ouch! The 74S74 (and its brethren) tries to pull down Q and /Q as well as up. Nothing like trying to short out the power supply!

Around 1974-75, I was working part time for a juke box and pinball outfit (which I think was controlled by the "outfit") and noted quite a few chip failures in certain types of games. It may be that some failures were just the nature of the beast. However, in thinking back on it, I believe circuit design errors brought about by naive designers were likely to blame for a large majority of failures. It didn't help that ventilation in many of the game enclosures was poor...

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PostPosted: Wed Nov 18, 2009 8:43 pm 
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Agreed. I made one mistake in a cabinet design of no ventilation fan. The motherboard draws 15 amps at 5 volts. Kept peeling flatpack legs off the board.

dinosaur: was the company in New Jersey located with branches everywhere? I worked for them for a year. I preferred my older manufacturing jobs at Romstar and SNK. I assume you heard of them :)

as a ps, am programming a pinball these days. Hit me up with an email, will throw you a source. 65c02 based.

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PostPosted: Thu Nov 19, 2009 9:22 pm 
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Thanks guys! Yes, all done with the aid of my trusty HP 1740A 'scope :) I probably could have done this with a logic probe instead, but a scope is much more insightful. After giving the keyboard a clean I was able to have a play - typing WAIT6502,0 and SYS4 brought back a few memories! Interestingly there don't seem to be very many working 3000/4000 series PETs out there - wonder what it's worth? - not that I'd look to sell it, as I don't reckon I'd ever end up with another working one in as nice conddition in this lifetime!
Cheers,
Pete


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PostPosted: Thu Nov 19, 2009 9:28 pm 
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Nightmaretony wrote:
dinosaur: was the company in New Jersey located with branches everywhere?

New Jersey? :?: The location I referred to was in Chicago. Periodically, ugly Italian-sounding guys with low eyebrows and sloping foreheads would come around. I'm sure they weren't there to extend any interest-free loans. :D

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as a ps, am programming a pinball these days. Hit me up with an email, will throw you a source. 65c02 based.

I don't fiddle with pinball anymore, but thanks for your offer. I'm curious: what are you using for an assembler?

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PostPosted: Thu Nov 19, 2009 11:04 pm 
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Kowalski. Definitely can use some features, I would love a line and program count and English instructions, but been able to do nicely. The debugger has saved my butt many times by acting as sandbox programming. Remind me to marry this program, or at least have carnal relations by the time all is said and done...

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PostPosted: Fri Nov 20, 2009 5:57 am 
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Nightmaretony wrote:
Kowalski. Definitely can use some features, I would love a line and program count and English instructions, but been able to do nicely.

You can get a line count by generating an assembly listing (there's also a symbol table listing, but screen only). There are some context instructions in the program (hit Ctrl-F1 and place the cursor on a mnemonic or macro) and an obscure Word document that gives some basic info. Otherwise, you're pretty much on your own.

As for features, the 65C02 emulation doesn't reflect modern versions of the MPU (try assembling STP or WAI), and the NMOS emulation has a rather obvious status register bug when BCD mode is in use. I've never been able to get an I/O window to appear. Also, too bad there's no '816 support, and good luck trying to mod the source code to include it.

The other assembler I had looked at is xa65, which is available as C source. It compiled with minor fiddling on my UNIX box (it compiles unaltered on Linux) but has a glaring omission in its design: it doesn't generate an assembly listing, making it essentially useless, in my opinion, for large scale projects. I can already hear the rebuttals, to which I say: No, I *don't* pick through symbol tables and then stare into an M/L monitor to do what an assembly listing would do for me.

My current assembler is a UNIX cross-assembler that works very well and assembles code very fast (about 8,000 lines per second). Only thing is it doesn't support the '816 and I don't have the source code. As I have a project involving the '816 in the works, I'm scratch-writing an assembler that runs under Thoroughbred Dictionary-IV (a very powerful, multiuser timesharing language in which I have developed for many years).

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The debugger has saved my butt many times by acting as sandbox programming. Remind me to marry this program, or at least have carnal relations by the time all is said and done...

May I suggest a willing woman instead? Mating with a computer while it is powered up could be very electrifying, downright shocking, in fact, and doing so while it's shut down will probably remind you of why you didn't stick with a previous girl friend.

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PostPosted: Fri Nov 20, 2009 3:31 pm 
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BigDumbDinosaur wrote:
Nightmaretony wrote:
Kowalski. Definitely can use some features, I would love a line and program count and English instructions, but been able to do nicely.

You can get a line count by generating an assembly listing (there's also a symbol table listing, but screen only). There are some context instructions in the program (hit Ctrl-F1 and place the cursor on a mnemonic or macro) and an obscure Word document that gives some basic info. Otherwise, you're pretty much on your own.


That helps out mucho. Thankee!



As for features, the 65C02 emulation doesn't reflect modern versions of the MPU (try assembling STP or WAI), and the NMOS emulation has a rather obvious status register bug when BCD mode is in use. I've never been able to get an I/O window to appear. Also, too bad there's no '816 support, and good luck trying to mod the source code to include it.


will switch when and if I go 816, but for this project, it has been a champ.....


The other assembler I had looked at is xa65, which is available as C source. It compiled with minor fiddling on my UNIX box (it compiles unaltered on Linux) but has a glaring omission in its design: it doesn't generate an assembly listing, making it essentially useless, in my opinion, for large scale projects. I can already hear the rebuttals, to which I say: No, I *don't* pick through symbol tables and then stare into an M/L monitor to do what an assembly listing would do for me.

My current assembler is a UNIX cross-assembler that works very well and assembles code very fast (about 8,000 lines per second). Only thing is it doesn't support the '816 and I don't have the source code. As I have a project involving the '816 in the works, I'm scratch-writing an assembler that runs under Thoroughbred Dictionary-IV (a very powerful, multiuser timesharing language in which I have developed for many years).



The time will come for you to release it, i hope to make the switch since you are here.


Quote:
The debugger has saved my butt many times by acting as sandbox programming. Remind me to marry this program, or at least have carnal relations by the time all is said and done...

May I suggest a willing woman instead? Mating with a computer while it is powered up could be very electrifying, downright shocking, in fact, and doing so while it's shut down will probably remind you of why you didn't stick with a previous girl friend.




My GF dumped me some years back when she left our movie gig. she played a famous movie monster in a David Lynch movie and last I heard was in a cult thing called drag me to hell. Tis fine, there are two wonderful ladies I talk to these days. Both actresses and down to earth :)
and was kidding with the carnal relations. Gotta have a smile in there...

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