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PeterO
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Re: Old School Fault Finding

Tue Feb 28, 2017 2:41 pm

scruss wrote:Your pictures are timing out, Peter — are you sure you're not hosting 'em on that 803? ;)
Indeed something seems to be "Up" with my web host....Their twitter feed says "We are having network problems"
Regarding memory usage, I'm learning you can do quite a bit with 32 Kw (@ 12 bits/word) in an emulated PDP-8 on the Pocket DEC Pretender (PDP) Zero
I'm working on getting my 803 Emulator working with GTK3 ready for release, but still a way to go yet.
PeterO
Last edited by PeterO on Tue Feb 28, 2017 2:46 pm, edited 1 time in total.
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

gregeric
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Re: Old School Fault Finding

Tue Feb 28, 2017 2:44 pm

PeterO wrote:Leave them with Jamie on the PiHut stand.
PeterO
OK, will do. Need any old valves?

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PeterO
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Re: Old School Fault Finding

Tue Feb 28, 2017 2:49 pm

gregeric wrote:OK, will do. Need any old valves?
I don't know. Best contact the museum direct as I know they only take specialist valves (i.e. not run of the mill TV and Radio valves).

PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

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rpdom
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Re: Old School Fault Finding

Tue Feb 28, 2017 8:49 pm

PeterO wrote:
scruss wrote:Your pictures are timing out, Peter — are you sure you're not hosting 'em on that 803? ;)
Indeed something seems to be "Up" with my web host....Their twitter feed says "We are having network problems"
Various CDNs seem to be having problems this evening. I believe one of the Amazon clouds is affected.

I won't be at the birthday bash, although I had considered it this year. Maybe next time I will inflict myself upon you all ;-)

Heater
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Re: Old School Fault Finding

Tue Feb 28, 2017 8:51 pm

PeterO,

Are you around Bletchley in early April?

Possibly, maybe, I will be making a trip back to Blighty then.
Memory in C++ is a leaky abstraction .

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Paul Webster
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Re: Old School Fault Finding

Tue Feb 28, 2017 9:23 pm

Memories flooding back so ... I've decided to go off to Bletchley tomorrow.

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PeterO
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Re: Old School Fault Finding

Tue Feb 28, 2017 9:33 pm

Paul Webster wrote:Memories flooding back so ... I've decided to go off to Bletchley tomorrow.
TNMOC is not fully open on Wednesdays, so check if a place is available on a tour before you go !
http://www.tnmoc.org/visit/opening-times
http://www.tnmoc.org/visit/guided-tours

PeterO
Last edited by PeterO on Tue Feb 28, 2017 9:35 pm, edited 1 time in total.
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

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PeterO
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Re: Old School Fault Finding

Tue Feb 28, 2017 9:34 pm

Heater wrote:PeterO,
Are you around Bletchley in early April?
Possibly, maybe, I will be making a trip back to Blighty then.
I'm sure I'll be there sometime in early April. I can make my visits to suit you as soon as you know when you are coming.

PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

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Paul Webster
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Re: Old School Fault Finding

Wed Mar 01, 2017 9:26 am

PeterO wrote:
Paul Webster wrote:Memories flooding back so ... I've decided to go off to Bletchley tomorrow.
TNMOC is not fully open on Wednesdays, so check if a place is available on a tour before you go !
http://www.tnmoc.org/visit/opening-times
http://www.tnmoc.org/visit/guided-tours

PeterO
Thanks a lot for that Peter. I had foolishly assumed it was fully open every day.
Trip now postponed until tomorrow and will play with LIRC today instead.

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W0LFIE
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Re: Old School Fault Finding

Wed Mar 01, 2017 1:01 pm

Oh the nostalgia of it, I'm just restarting my 'radio shack' at home, using a Pi of course for Digital TV Transmission (on the cheap), it's the reason why I'm here on the Forum..

But working on stuff like that is bread n butter and much easier to chase components and wires around. I'm still working in Electronics, the Scope is on nearly every day for something or other, but... I'm working with this sorta thing now, I hardly dare cough..

IMAG1385ss.jpg
IMAG1385ss.jpg (40.46 KiB) Viewed 2806 times
:
Time flies like an Arrow, Fruit Flies like a Banana.

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rurwin
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Re: Old School Fault Finding

Wed Mar 01, 2017 1:35 pm

PeterO wrote:
Heater wrote:Incredible!
500cps paper tape reader. Never seen such a fast tape reader.
The ultimate development of that design (Used by Elliotts on the 4100 range and ICL on the 1900 range) ran at 1000 cps. I've never seen one working :-(
Nor have I but some guys when I was at school around 1976ish went on a field trip and reported a tape reader that must have been around that speed. They said the tape flew six feet across the room and folded up in the air before falling into the bin provided. I wish I'd seen it.

Heater
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Re: Old School Fault Finding

Wed Mar 01, 2017 4:08 pm

W0LFIE,

That is great.

I recently discovered that working with surface mount components, by hand, can be easier than the the old through hole stuff. None of that messing around drilling hundreds of holes in your home made PCB, poking leads through holes, snipping off the tails. Etc.

With the large size SMD resistors, caps and such you can weld them between the pads of a proto-board very easily.

Mind you, those tiny components in your picture might be a challenge....
Memory in C++ is a leaky abstraction .

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PeterO
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Re: Old School Fault Finding

Wed Mar 01, 2017 4:49 pm

Paul Webster wrote:
PeterO wrote:
Paul Webster wrote:Memories flooding back so ... I've decided to go off to Bletchley tomorrow.
TNMOC is not fully open on Wednesdays, so check if a place is available on a tour before you go !
http://www.tnmoc.org/visit/opening-times
http://www.tnmoc.org/visit/guided-tours

PeterO
Thanks a lot for that Peter. I had foolishly assumed it was fully open every day.
Trip now postponed until tomorrow and will play with LIRC today instead.
Good, I'm glad I was able to save you a wasted trip !. TNMOC is not fully open every day because historically there were never enough volunteers to open it every day. Now the "closed days" are often used for Educational and Corporate visits/event which bring in needed revenues.

Saturday is the best day to visit as that's the day the most "volunteer engineers" are present and more of the bigger machines are in operation.

PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

gregeric
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Re: Old School Fault Finding

Wed Mar 01, 2017 5:26 pm

Heater - those SMDs are big enough to have their value stamped on them, so I assume they're 0805s, which aren't so bad.

I'm using 0805s & SOT23s without protoboard, instead mounting them on double-sided tape stuck to SRPB. I'm making pleasingly compact circuits as a result. You can butt the SMD components right up to each other to make solder-able connections. Even flip packages over if it better suits the layout.

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W0LFIE
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Re: Old School Fault Finding

Fri Mar 03, 2017 7:57 am

Yep there are smaller ones (the package names mean now't to me though), if one drops on the Antistatic mat black side up, forget it, much simpler to pull another off the tape.

Building prototypes up (even in mid air) can be pretty simple, the old mid air rats nest of wires is a distant memory and adding these new things into old school technology to add features (ie a heartbeat LED/Res in a space of around 4mm) is amazingly simple.

I noticed that some of you started even earlier than myself! My old 1979 Superboard II is still in the Loft and it works. I pulled it out some years ago and plugged an EPROM emulator into it to rewrite some of the OS, I had to whisper in it's ear.. "now this is gonna seem like magic to you"..
:D
:
Time flies like an Arrow, Fruit Flies like a Banana.

gregeric
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Re: Old School Fault Finding

Fri Mar 03, 2017 8:10 am

Seems we are living parallel lives Wolfie! My teenage obsession:
Image
Homebrew firmware held in CMOS RAM, battery backed. Seemed like a good idea at the time ;) but I think one of those DIP switches enables the EEPROM. Trouble is, I documented not a single thing :(

These days we get to play around the edges, not do major surgery. But still fun!

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W0LFIE
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Re: Old School Fault Finding

Fri Mar 03, 2017 10:29 am

Is that 1K memory? :D laughable nowadays.

Frightening, the amount of program you could get in the standard memory.. 4K?

I removed the UK 50FPS PCB since my monitor would handle 60, gave it a voice using the BBC Micro Chip and got the memory up to a mind blowing 16K with a daughter board above the mem chips. Doubled the Screen memory too then had to rewrite the OS to clear it all fully on startup.

Poor Old PSU was barely man enough to handle all the extra chips so I changed anything I could to the HC versions.

I also have a colour Graphic PCB which I never fitted.
:
Time flies like an Arrow, Fruit Flies like a Banana.

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PeterO
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Re: Old School Fault Finding

Fri Mar 03, 2017 10:40 am

Sadly there is no photographic evidence of my earliest machines, though I do still have (somewhere) the documentation and some of the boards. I'll dig them out and take some pictures later.
PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

gregeric
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Re: Old School Fault Finding

Fri Mar 03, 2017 10:58 am

It might have been 1 or 4K from new, with sockets to populate it to 8K (the 2114s pictured there in the sockets are just so I don't lose them, shouldn't be there when operating).

By the end of my modifications, it had 32K of CMOS RAM for main memory, and a 2MHz :shock: 65C02 sitting next to it. And on the right the 6510 PIO.

Sitting above the EEPROM/CMOS are the graphics mods - UK 50Hz refresh & RAM, not ROM, for the character table & thus custom graphics.

Topmost is the superfast modem for tape storage, I think from Everyday Electronics or similar publication. The designer of that had a memorable name - Hugh Koanantikool or something like that!

gregeric
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Re: Old School Fault Finding

Fri Mar 03, 2017 1:44 pm

Still at it, only the scale is different. Warranty voided 10 mins after arriving in post :D :
Image
The Zero isn't far off the size of that 40-pin DIL 65C02 :geek:

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