Author Topic: Adventures in old 80s computers.  (Read 27063 times)

Offline S. Heslop

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Adventures in old 80s computers.
« on: July 29, 2014, 11:16:28 PM »
This might be a bit bizarre for this forum, but hopefully people will find interest in it. Also, as a disclaimer I'm not really very knowledgeable about these old computers, or computers in general. I only know as much as I can Google!

Currently i've been messing with an Atari 520ST-FM I found at a boot sale for a bargain.

First thing I had to make for it was a video cable to hook it up to an old LCD TV. This model of Atari ST has an RF out for use with TVs, but it gives pretty rubbish quality video. I'm using this diagram that I found with a quick Google search.


I shoved the 13 pin din connector into an eraser to prevent the pins from wandering when the plastic got soft from the heat. The pins didn't have solder cups and it was pretty tight getting everything soldered.


There was more space on the scart side, but it was even more of a fiddle making sure every cable went where it was supposed to.


See if you can spot the typical mistake.


The cable works!


For a while I was thinking that the floppy disk drive wasn't working since it was giving errors when I tried open an unformatted disk. I had the drive partially disassembled, cleaned, and put back together twice before I found the menu item (under the file tab) to format it. Doy! Glad I didn't go as far as replacing all the electrolytic capacitors before finding that.

After that I had to hook up the old Windows XP computer (it's funny to think it's more than 10 years old now) since it's the only one I've got that can still support a floppy drive.

At first I was trying to use the floppy image program to write disks but it was giving me no results. Disks were ending up corrupt at best, and crashing the Atari whenever I tried open them. Which after some reading might be due to the image files I was trying to write having more cylinders or sectors than a PC floppy drive can write reliably.



Then I tried using the Windows command prompt to format the drive (typing "format a: /t:80 /n:9", for 80 cylinders and 9 sectors) with tape over the right hand hole in the disk to fool the drive into thinking it's an older 720kb double density disk, rather than 1.44mb high density.



Then after simply copying files over in Windows explorer, like you would any other files...



It worked! I'm running a music demo that includes this tune. It's the first demo tune I ever heard. Honestly I'm a little bit embarrassed posting it, since it's fairly corny and limited music. But it's probably worth showing what kind of sound this system is famous for. There's music programs that can support low-fi samples but they take up too much CPU power to be too useful.

Unfortunately this only works for things released as regular folders. Alot of Atari ST programs seem to be distributed as .st and .msa image files that require that floppy image program to write them, so i'll need to figure out that whole thing at some point.






But with the Atari ST working it's now time to bring out the big guns. I've had these stored under the bed for a while now, the older 'breadbin' style Commodore 64 up top used to belong to my uncle, but it unfortunately doesn't work (but still has useable components). The C64C below was bought on ebay, along with a few accessories like a mouse adapter and a midi cartridge for controlling the audio from a newer computer.

What makes the C64 an interesting computer is it's famous 'SID' sound chip. It's more or less a little analogue synthesizer on a chip, complete with a filter. It was very advanced (and weird) for it's time, and is still well renowned for producing a great sound. On its own it's fairly limited, with just 3 oscillators and the single filter to share between them (that's not to say that it can't produce decent music on its own though!). But it has alot of potential as a musical instrument to accompany other stuff.

The only problem is that with 5 1/4" floppy disk drives, cables galore, a monitor, switches, and power adapters it's awkward to use and takes up way too much desk space. So the plan is to try make a single compact self-contained case for everything, with just a single power cable to worry about. First i'll have to measure and draw up the various boards.


As a side, check out these fantastic game covers.

Offline Pete49

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Re: Adventures in old 80s computers.
« Reply #1 on: July 30, 2014, 12:05:16 AM »
How to restore memories.  :thumbup: I still have a TRS 80 with tape drive and the ubiquitous C64 and don't have the heart to toss them out. I'll be watching this thread  :ddb:
Pete
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Offline rockknocker

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Re: Adventures in old 80s computers.
« Reply #2 on: July 30, 2014, 12:54:15 AM »
Great work! These old computers have a lot of character, and its nice to see them working again! I'll be following this project closely.
Anything is possible when you forget what's impossible.

Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #3 on: July 30, 2014, 08:48:54 AM »
I also have a few old computers. Still use them occasionally.

As for the mistake.  I've done it with thirteen Amp plugs before today.

An interesting post that I will certainly follow.

Dave.

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #4 on: July 31, 2014, 12:21:49 PM »
Don't start me on old computers...... I have a room full of Sharp MZ80K, A and Bs, with disks & printers, a handful of Sinclair QLs, an old Amiga kicking around somewhere, an Osborne OCC-1, a MicroVAX-3100, plus a load more...

I plan to hook some of the Sharps up to Arduinos & use them for data capture - just for a laugh really, and because they look cool compared to the <s>beige</s> black box/laptop.
Cheers!
Ade.
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #5 on: July 31, 2014, 03:29:35 PM »
Don't start me on old computers...... I have a room full of Sharp MZ80K, A and Bs, with disks & printers, a handful of Sinclair QLs, an old Amiga kicking around somewhere, an Osborne OCC-1, a MicroVAX-3100, plus a load more...

I plan to hook some of the Sharps up to Arduinos & use them for data capture - just for a laugh really, and because they look cool compared to the <s>beige</s> black box/laptop.

That's an impressive collection. Especially the Osborne!

Offline Brass_Machine

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Re: Adventures in old 80s computers.
« Reply #6 on: July 31, 2014, 05:07:00 PM »
ahh... the memories. I had an Atari 1040st. Those were the days... Loading a game via tape (on an atari 800xl)! beeeeeeeep. Braaaaaaaap.
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #7 on: July 31, 2014, 06:28:53 PM »
In my lifetime i've only ever loaded one game off of a tape. It took so long I didn't want to do it again!

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #8 on: July 31, 2014, 10:54:16 PM »
I have an Amiga 2000, I think a 500, once built an LNW-80 from bare boards (a hopped up color high speed (4mhz!) TRS-80 that I overclocked to 5.33 Mhz.), and I even have an original stock IBM PC stored away.

The last 16 bit computer I used was an old AT 486 DX66 clone, that served up until 5 years ago as a router under Coyote Linux, loaded off a floppy.

I'm thinking of resurrecting it yet again to run TurboCNC under DOS. The thing is a tank -- all metal case.

Anyway, following your progress Simon with great interest. As I mentioned FORTH works great with these old machines if you get into programming -- makes them lightning fast with tiny memory usage, and 16 x 64 screens are perfect for it. Easy to embed assembly language in it to do miraculous stuff, considering the age of these things.
I love it when a Plan B comes together!
Steve
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Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #9 on: August 01, 2014, 02:08:56 AM »
One of the big advantages with the old 8 bit machines,  particularly the BBc series,  was the number of pors available.

My Dell Inspiron lap top, three year old, only has three USB ports, one LAN port and it's dvd drive. Oh yes,  and the smart card dock. A bit limiting for experimental work.

The 486 below it has numerous serial ports + the LAN and a collection of jack sockets. As well as the 3.5" floppy and the DVD/CD drive.

And, of course,  that super useful printer port.

Dave.

Offline dawesy

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Re: Adventures in old 80s computers.
« Reply #10 on: August 01, 2014, 11:53:38 AM »
I have my C64 but the tape player doesn't work. Tried cleaning the heads and adjusting the azimuth but no joy :( have some classic games for it too.
Lee.
wishing my workshop was larger :(

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #11 on: August 01, 2014, 12:07:30 PM »
I think any old casette player will work, you just have to add a connector to suit.

Most old tape players suffer from hardening/deterioration of the rubber pinch wheel. Sometimes a cleaning or even a light sanding with very fine paper will give the rubber enough grip. Speed variation can sometimes prevent the proper data playback. Often players used a rubber ring drive belt that goes bad and can be replaced.

I wouldn't be surprised if someone hasn't worked out a way to do a fake playback sound from a modern computer's headphone jack to load programs into an old 8 bit machine that had no other means of transfer. Though a homemade serial null modem might be another way of loading files if the comp was capable of using a modem.

Maybe you could also make a cart. I used to program eproms through a homemade parallel port eprom programmer, and erased them with a sunlamp.
I love it when a Plan B comes together!
Steve
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Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #12 on: August 01, 2014, 12:15:29 PM »
 These two links may come in useful for anyone who finds their Dallas Clock battery is dead.  It could keep a few old machines running,  and it is madmodding at it's finest.

http://www.mcamafia.de/mcapage0/dsrework.htm

http://classic-computers.org.nz/blog/2009-10-10-renovating-a-dallas-battery-chip.htm

Dave.

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #13 on: August 01, 2014, 12:31:09 PM »
Now these 'old' computers you are talking about are really quite modern !

When I first started using computers in the late 1960's they were pretty enormous, big cabinets with separate bays for the CPU and memory etc. We has serial CPU's and parallel ones, the former being the economy version as it cut down of the number of circuits required. Main memory was 'Core Store' - tiny ferrite rings threaded onto an X, a Y a 'Sense wire' and an 'Inhibit wire'. Backing storage was Drum memory and later rigid 'head per track' disc memory.

I well remember one night having to replace the 'disk enclosure' at a Mobil oil refinery - 2 megabytes of memory, but the system only took in high level language and compiled it at load time (Fortran in this case). I worked out that that night we had loaded 14.1 MILES of paper tape to reconstruct the 2 Mbyte disk image  :ddb:
Andrew Mawson
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #14 on: August 01, 2014, 01:05:16 PM »
I saw a thing a while ago where someone was programming for one of those gigantic 60s computers on punch tape. The punching machine was extremely noisy, sounded like a vacuum cleaner, and there was no facility to erase mistakes of course. Really makes me appreciate this modern era! When I was programming in Microsoft's visual studio it even had something like a spell check that told me if i'd made any typos, and an auto-complete to help me remember variable names. Although I've heard some more serious programmers complain that that kind of stuff stops you from actually 'thinking' about the code and how it works.

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #15 on: August 02, 2014, 06:28:21 AM »
When I was programming in Microsoft's visual studio it even had something like a spell check that told me if i'd made any typos, and an auto-complete to help me remember variable names. Although I've heard some more serious programmers complain that that kind of stuff stops you from actually 'thinking' about the code and how it works.

I still program in VS (2010 now, but I still prefer 2008); and yes, the autocomplete can be quite invasive (a bit like the so-called auto-complete on my phone, which makes more mistakes than I do). It doesn't, to my mind, stop you thinking about the code & how it works - if anything, freeing one from the drudge of having to remember exact variable names (and how they're cased if you're working in C#), frees one up to think more about the code, its structure & what its doing...

What it DOES hide from you, completely and utterly, is how inefficient the end result is. I was a lucky lad, having a Sinclair QL to play with - a cavernous 128K of ram, and a "blisteringly fast" MC68008 CPU (which was severely hobbled by it's 8-bit data bus - if only Sir Clive had stumped a few extra pounds up and used the MC68000 and got that 16 bit data bus that the Atari ST & Amiga made such good use of). Even so, one had to write tight efficient code to have it run at any kind of sensible speed. Not these days, most CPUs are idling most of the time, there's so much power in your average computer that utter garbage code still runs like a greased rat up a drainpipe.
Cheers!
Ade.
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Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #16 on: August 02, 2014, 06:36:19 AM »
Don't start me on old computers...... I have a room full of Sharp MZ80K, A and Bs, with disks & printers, a handful of Sinclair QLs, an old Amiga kicking around somewhere, an Osborne OCC-1, a MicroVAX-3100, plus a load more...

I plan to hook some of the Sharps up to Arduinos & use them for data capture - just for a laugh really, and because they look cool compared to the <s>beige</s> black box/laptop.

That's an impressive collection. Especially the Osborne!

I dug the Osborne out last night... it "almost" works (the screen is exhibiting some kind of horizontal hold/echo/blurring problem), and neither of the disks in the case would boot, although I have a feeling that's because neither of them are boot disks. I think the problem is a dry solder joint, or possibly some dead caps, so I need to get inside it & have a furkle... Time will tell.

I missed a couple of machines out... I have a CBM 8032 with disk drives & printer (the 8032 being one of the last PET style computers). I used to have the holy grail - a fully working CBM PET 2001 with chiclet keyboard & "built in" tape deck (Actually a bog standard CBM cassette unit, held in a bracket & sticking out of a hole in the PET casing), but it is no longer with me unfortunately. Also I have, of course, a BBC B, a Tatung Einstein, a couple of Commodore SX-64's (the "portable" CBM64, with built-in screen & disk drive), a ZX81, no Spectrum oddly enough. Oh, I think there's a Commodore C128 lurking in a box somewhere...

Of course, I never USE any of the damn things, I probably ought to move most of them on... the QLs and Sharps I'll keep for sure, and the Ozzy... and the CBM, er, bugger.
Cheers!
Ade.
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Offline dawesy

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Re: Adventures in old 80s computers.
« Reply #17 on: August 02, 2014, 08:54:13 AM »

I think any old casette player will work, you just have to add a connector to suit.

Most old tape players suffer from hardening/deterioration of the rubber pinch wheel. Sometimes a cleaning or even a light sanding with very fine paper will give the rubber enough grip. Speed variation can sometimes prevent the proper data playback. Often players used a rubber ring drive belt that goes bad and can be replaced.

I wouldn't be surprised if someone hasn't worked out a way to do a fake playback sound from a modern computer's headphone jack to load programs into an old 8 bit machine that had no other means of transfer. Though a homemade serial null modem might be another way of loading files if the comp was capable of using a modem.

Maybe you could also make a cart. I used to program eproms through a homemade parallel port eprom programmer, and erased them with a sunlamp.
Cheers for that I'll have a look into it. Be good to get it up and running again :)
Lee.
wishing my workshop was larger :(

Offline John Swift

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Re: Adventures in old 80s computers.
« Reply #18 on: August 02, 2014, 10:47:53 AM »
I remember building a Sinclair ZX81 from a kit  - it worked first time !

there is still a number of ZX fans building their own ZX 80 and ZX 81 from scratch
http://searle.hostei.com/grant/zx80/zx80.html#ROM

last night I wished my PC had the same linear power supply
I switched on and bang  , the lights went out  :doh:

a capacitor in the mains filter had failed - the power supply works OK without it  :D

       John

PS
any one want to build a NASA guidance computer ?
http://www.galaxiki.org/web/main/_blog/all/build-your-own-nasa-apollo-landing-computer-no-kidding.shtml




Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #19 on: August 02, 2014, 11:17:15 AM »
Don't start me on old computers...... I have a room full of Sharp MZ80K, A and Bs, with disks & printers, a handful of Sinclair QLs, an old Amiga kicking around somewhere, an Osborne OCC-1, a MicroVAX-3100, plus a load more...

I plan to hook some of the Sharps up to Arduinos & use them for data capture - just for a laugh really, and because they look cool compared to the <s>beige</s> black box/laptop.

That's an impressive collection. Especially the Osborne!

I dug the Osborne out last night... it "almost" works (the screen is exhibiting some kind of horizontal hold/echo/blurring problem), and neither of the disks in the case would boot, although I have a feeling that's because neither of them are boot disks. I think the problem is a dry solder joint, or possibly some dead caps, so I need to get inside it & have a furkle... Time will tell.

I missed a couple of machines out... I have a CBM 8032 with disk drives & printer (the 8032 being one of the last PET style computers). I used to have the holy grail - a fully working CBM PET 2001 with chiclet keyboard & "built in" tape deck (Actually a bog standard CBM cassette unit, held in a bracket & sticking out of a hole in the PET casing), but it is no longer with me unfortunately. Also I have, of course, a BBC B, a Tatung Einstein, a couple of Commodore SX-64's (the "portable" CBM64, with built-in screen & disk drive), a ZX81, no Spectrum oddly enough. Oh, I think there's a Commodore C128 lurking in a box somewhere...

Of course, I never USE any of the damn things, I probably ought to move most of them on... the QLs and Sharps I'll keep for sure, and the Ozzy... and the CBM, er, bugger.

How did you come into possession of such a collection? Two SX-64s is insane!

Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #20 on: August 02, 2014, 08:55:23 PM »

I've been taking taking a look at the MaxYMiser music tracker for the Atari. I know a little bit about trackers but the instrument editor in this one is taking a bit of getting used to. But at least it has a relatively nice GUI compared to the nightmares that await me with the C64.



I took apart the C64C to measure the bits I want to keep.


Kinda interesting that the thing is held together with tabs. Even the keyboard is held in with tabs. Only the motherboard is held down with screws.


The whole thing is shielded.


No surface mount in sight.


And here's the famous SID chip. The lower number gives you the date, the chip was made in 1992, which is fairly late (they stopped making them in 93). Later is better with SID chips since the earlier revisions were fairly buggy, and some didn't have things like fully working filters or waveform combining.


Drawn up the keyboard and the motherboard.

I'm planning to make this thing reasonably compact, but i'm still not sure what i'm exactly going for. I could make something like this but imagining it with half an inch of dust settled on top and between the keys, it might be better to make something that folds or has a lid.

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #21 on: August 03, 2014, 05:20:46 AM »
Of course, I never USE any of the damn things, I probably ought to move most of them on... the QLs and Sharps I'll keep for sure, and the Ozzy... and the CBM, er, bugger.

How did you come into possession of such a collection? Two SX-64s is insane!

Ah, well, too much time & money on eBay mostly.... It's the usual thing, my old QL had died & I was feeling a bit nostalgic one night, some beer had been consumed, and I ended up purchasing another one. One thing led to another & before you know it I'm buying "any computer I ever used in the 1980s", then "any computer from the 1970s/1980s"... I must have had 30-40 machines at one point. That got whittled down quite a bit when the ex persuaded me to sell a bunch of them off (I think she wanted access to the garage), and has slowly grown again since she became an ex...

The ZX81 was kindly donated to me by the late AndyF of this parish; like everything of Andy's it was a study in neatness, being attached to a small baseboard with all of the leads & power pack attached "just so" with it; even the wobbly RAM pack is firmly affixed to the board to prevent the dreaded wobble... Sadly, the tape deck has died, but the ZX81 soldiers on...

Edit to add: The height of the madness was owning 2 HP1000 mini computers, each with separate tape & IO units, and each with 2 disk drives, and an HP A700. Each HP1000 had its own 6ft tall rack unit, the tape decks were a 2nd 6ft rack unit, the disk drives were about the size of a washing machine each, and the A700 came in its own 6ft cab which, I'm sure, was milled out of cast iron, it was massively heavy. I eventually sold them off as I couldn't do a damn thing with them, one went to a mainframe museum, the other spent some time in someone's kitchen before being moved on again to unknown pastures. I can't remember who got the A700. Crazy days...
Cheers!
Ade.
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Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #22 on: August 03, 2014, 06:36:37 AM »
I really hanker after an Ampex TM7 or TM9 reel to reel tape backing store. I used to work on them in my callow youth.

They had three servo systems, one for each reel, and one for the capstan. Between the capstan and each reel was a vacuum column with a U shaped loop of tape that acted as a buffer to give the reel servos a bit of lee way, so for short back and forth reads or writes just the loops moved and the reels stayed still. Each loop had a photo sensor at each end, and when triggered the appropriate reel would kick in and wind a bit of tape. Lovely to see working when properly set up, and remarkably trouble free.

Biggest problem was carbon dust from the vacuum motors (that looked like a domestic cleaner motor) getting onto the electronics. There was a filter on it but they used to fall off! Followed by failure of the 'pea' bulbs in the photo sensors. If well used the heads would wear, increasing the head gap and reducing the output signal. (Complex heads - head per track (7 or 9), with a read after write head and an all track erase head)
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #23 on: August 03, 2014, 07:57:09 AM »
 :coffee: :coffee: :coffee:
I love it when a Plan B comes together!
Steve
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #24 on: August 03, 2014, 06:11:33 PM »


Here's one idea i'm looking at. It's a breadbin! Geddit?!

Looks kind of ridiculous, but i'm tempted to roll with it for the pun. It'd also keep the dust off the keys, but i'd prefer to go for a flat top for when this thing inevitably ends up in storage, or to rest stuff on top of in general.

Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #25 on: August 03, 2014, 06:21:12 PM »
Thinking about it some more, I could make a portion of the top flat. And the fact that I can't put stuff on top of it might actually be beneficial.

Another thing I was thinking of was copying this and maybe sticking some reference sheets to the inside of the lid, but I can see myself having to take off all the accumulated junk from the top every time I want to open it.

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #26 on: August 03, 2014, 07:33:59 PM »
Why not go with a drop-front breadbin?



It's got a handy flat top, and if you sellotape (ahem, affix in a professional manner) the keyboard to the fold-up front, you've got plenty of space inside the bin for the actual gubbins :)
Cheers!
Ade.
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #27 on: August 03, 2014, 09:11:08 PM »
Why not go with a drop-front breadbin?

Never thought about making the keyboard flip out. I'd only considered making the monitor flip up like a laptop. Although to be honest I want to have a go at making one of those bureau style shutters for the sake of it.

But i'll keep it in mind for if I find out the shutter idea won't leave me enough room for the power adapters (I still need to measure them up).

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #28 on: August 03, 2014, 10:35:43 PM »
Leave a small space to put some actual bread or crackers in it, too, for late night snacking!
I love it when a Plan B comes together!
Steve
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Offline DMIOM

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Re: Adventures in old 80s computers.
« Reply #29 on: August 04, 2014, 03:06:15 AM »
Leave a small space to put some actual bread or crackers in it, too, for late night snacking!

to feed the mouse ?    :palm:

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #30 on: August 04, 2014, 08:00:50 AM »
no,no, bread boxes keep the mice out....

I was eating Ritz crackers when I wrote that other last night.....
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #31 on: August 04, 2014, 04:00:51 PM »
I'll have to use breadboard somewhere in this project. Christ...


I was up all night last night reading about assembly programming. People who can program in assembly are often very proud of themselves, and act like they're gods gift to computer science. But from what I've read (and to be fair I'd only read the beginnings) it seems amazingly straight forwards. It's probably hell to write a program of any serious length in it, but for coding things like C64 demos it seems fairly intuitive. Especially compared to the more ethereal stuff in high level languages like polymorphism.

Reading about it has made me kind of want to skip the whole project and just head straight to covering my desk with all the junk to try out making some simple classic effects. Although it's probably better to leave that till i've got a better setup.

I remembered I had this in the box of my uncle's old stuff too.





It's mostly devoted to C64 BASIC but has a nice rundown of the assembly op codes and the memory map in the back.

Offline PekkaNF

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Re: Adventures in old 80s computers.
« Reply #32 on: August 05, 2014, 02:12:45 AM »
I remembered I had this in the box of my uncle's old stuff too.


It's mostly devoted to C64 BASIC but has a nice rundown of the assembly op codes and the memory map in the back.

That was my book t learn programming (and english!)! I probably tested every page and wrote every code it had.

Pekka

Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #33 on: August 05, 2014, 03:31:19 AM »
S Heslop,

...But from what I've read (and to be fair I'd only read the beginnings) it seems amazingly straight forwards.

Hmmm,  it's not quite as easy as that. Assembler is very unforgiving of your errors.

You do need to read a but further.

But it is very interesting.  and lightning fast once you have it de-bugged.

Dave.


Offline Bluechip

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Re: Adventures in old 80s computers.
« Reply #34 on: August 05, 2014, 05:55:37 AM »

Hmmm,  it's not quite as easy as that. Assembler is very unforgiving of your errors.

Dave.

Oh boy ! have to agree with that.   :thumbup:

Remarkable just how many times you can check errant code without seeing what eventually turns out to be so blindingly obvious you begin to doubt your sanity ...  :bang:  :bang:

Dave [ another ] Ex BBC 'B' & Nascom owner

 
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Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #35 on: August 05, 2014, 10:32:57 AM »
Dave,

And don't you just love the way that erroneous assembler programs can rampage through your system like Atilla the Hun on one of his bad days.
There is NO room for error.

Dave

Assembler86 on PC 386 and Z80 Assembler on the TRS-80.

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #36 on: August 05, 2014, 10:39:56 AM »
Once you manage to get a protected mode kernel running as supervisor, you can then run your assembler under it's supervision at a lower interrupt priority, saving your copy of the register set on exit. All that Pushing and Popping on the stack ! Then when you think it's all stable the dreaded 'stack overflow' error rears it's ugly head  :ddb:
Andrew Mawson
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Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #37 on: August 05, 2014, 12:02:10 PM »
That's more or less what I mean by "it's probably hell to write a program of any serious length", it seems the difficulty would be keeping track of stuff as it gets bigger.

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #38 on: August 05, 2014, 05:51:53 PM »
Z-80 had the signifigant bites in the opposite order, too. I used to actually recognize op codes.

It was easier to just write most code in FORTH for me and include assembly subroutines (well "words" in FORTH) in it. FORTH had a built in assembler, so definitions for a word could be either FORTH words or assembly language. It didn't care.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #39 on: August 06, 2014, 10:20:24 AM »
I spent ages (literally) typing in an Assembler program written in Sinclair SuperBASIC. The listing was printed over 4 or 5 months in QL World magazine.

Being young and naive at the time, I hadn't realised that Assembler was not the same as Compiler.... I thought it would take my BASIC programs and turn them into super-fast machine code.... oops.

IIRC The program was nicknamed QSLUG in recognition of its slowness...
Cheers!
Ade.
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Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #40 on: August 06, 2014, 12:55:30 PM »
I would be interested to know which computer members first used. And which one they did their first programming on.

My first experience with computers was in 1980 when someone left an (I think) Olivetti machine with me and invited me to 'have a play' with it.

But it was a TRS-80 Model 1 that I learned to program on. Ik of ram, tape for storing my master pieces and only two string functions. A$ and B$.

And, naturally, upper case only.

This lead,  years later when I was at Huddersfield Poly', to me getting a reputation for writing very 'user hostile' programs.

Dave.

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #41 on: August 06, 2014, 01:35:11 PM »
My first programming experience was weekly sessions in 1968 sitting in front of a Teletype which was on line to a time sharing bureaux. I was writing short routines in Fortran processing measured values for the spectral response of military infra red detectors. It was a slow, long winded business all at 110 baud.

My first owned computer was one I designed and made in 1973 using the Texas 74181 'bit slice' ALU chip set, and was micro-programmed using a diode matrix to form the actual instructions from sequences of logical operations. I think I had 1k of actual RAM. All wire wrapped on home etched boards! Amazingly it worked.

My first non home brew was in about 1975 - an S100 bus machine using initially an 8080 CPU board, and later a Z80 one from 'Tinker Toys' and it was this one that I used to get to grips with assembler coding.

All this well before 'PC's' arrived on the scene.
Andrew Mawson
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Offline Bluechip

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Re: Adventures in old 80s computers.
« Reply #42 on: August 06, 2014, 01:41:01 PM »
BBC B+ with a 5" Floppy  [ disk that is ....  :lol: ], at least I did until it got run over. Also had a Nascom 'B' [ I think ] but never got into that thing really. Eventually gave it to a bloke I used to work with at IBM - he was collecting ancient pre-PC stuff. Commodore, Dragons etc. etc.

Then did nowt really until about 1997-ish when PE started faffing with the 16F84 and TK2 .

Dave

I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #43 on: August 06, 2014, 03:12:18 PM »
How did you manage to run over your computer ?

Dave.

Offline S. Heslop

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Re: Adventures in old 80s computers.
« Reply #44 on: August 06, 2014, 03:34:34 PM »
Being born at the start of the 90s, Windows 95 was in full force by the time I got old enough to really use computers.

I said it before but it must've been great to live in a time when computing magazines were actually about computers. By the time I was looking at PC magazines they were more aimed towards people with little knowledge about computers, and never got more technical than installing antivirus software.

I guess the 'real computing' stuff all migrated to the internet, and I didn't get an internet connection till 2005. My parents got caught up in the news hysteria about it and really believed the internet was nothing but chatrooms and pedophiles.

Offline philf

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Re: Adventures in old 80s computers.
« Reply #45 on: August 06, 2014, 04:03:31 PM »
My first programming was at Manchester Poly using Fortran. We had to hand punch cards and leave them with a technician to be run and then collect the results next day. The only alternative then was my trusty Thornton P221 Comprehensive Log Log Slide Rule.

In my early days at work I had adventures with an HP 9825 and a pen plotter. I was intent on building bike frames and wrote a program to plot out patterns which when wrapped around a tube would provide a template to cut to so that two tubes would meet perfectly. I also mass produced my Christmas cards on the HP plotter one year.

My next venture into Basic was with a Commodore PET in my lunchtimes.

My first home computer was a second hand ZX81 which didn't work properly - random characters kept popping up on screen - the guy I bought it off was reluctant to give me a refund saying it had always done that - never thinking that there had been a fault.

I went upmarket then with an Acorn ATOM which had 2K RAM. I bought some surplus boards (where have all the shops gone that used to sell such stuff?) and desoldered the memory chips to expand the ATOM to all of 12K.

I only had the ATOM for a couple of weeks when I was offered a BBC model B. BBC Basic probably still is the best. I designed and built a flat bed pen plotter to use with the BEEB which could even be used to list out programs. The program was all in BASIC and worked remarkably fast considering the speed of the processor. (1MHz). Someone at work bought a Watford DDFS interface which was soon cloned and this gave me access to the luxury of 3.5" Floppies rather than the tedious cassette. Another lunchtime project was making sideways RAM boards into which you could load ROM images from the floppy drive. The program to run the sideways RAM was a mixture of Basic and machine code.

Jumping forward to the 21st century and BBC Basic is very much alive and well and is available to run on Windows (up to and including 8.1) and Linux. There is a free version of BBC Basic for Windows (limited to 16K programs) or for £29.99 you can use up to 256Mb and compile your programs into executables. This is on my list of to-dos as I wrote dozens of programmes to do all sorts of engineering calculations. See http://www.bbcbasic.co.uk/bbcwin/bbcwin.html

I still have 2 BBC Model Bs and a BBC B+ with 64K memory. I suspect none of them would switch on without replacing a few capacitors having been unused for so many years. I do miss the virtually instant start-up and occasionally hanker after playing Repton.

I'm sure that having limited memory forced people into writing efficient code. Many years ago a colleague and I developed a document management system which used VBA (Visual Basic for Applications) to interface Autocad with Excel. A bizarre feature was that you could write a few hundred lines of program and then find a function which could reduce the job to say 10 lines. You would imagine that the file containing the VBA would then be smaller as a result of losing 90 lines. Not so - our friends at Microsoft for some unknown reason never actually deleted anything you wrote even though you thought you'd got rid of it! Thus your more efficient programme was in fact bigger than the less efficient one. You couldn't access the deleted stuff in History so why keep it? The only way round this was to export the modules one by one in to a new project. It made me wonder if all Microsoft software was the same.

Phil.


Phil Fern
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Offline Bluechip

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Re: Adventures in old 80s computers.
« Reply #46 on: August 06, 2014, 05:30:39 PM »
How did you manage to run over your computer ?

Dave.

Alas, 'tis a sorry tale ... The village where I lived had a 'Beeb' computer club on Thursday evenings at the local primary school. So, resplendent in our flares and kipper ties we assembled with our kit to boast of our prowess and swap code etc.
I was just about to open the tailgate to load the Beeb etc. into the car and set off when a joiner/shop-fitter mate arrived in his van with a load of really nice strip-wood for use on my model boats. In order to get this stuff into the garage I needed to move the car, so reversed it up the drive ( instead of using the front door, in which case I would have noticed I'd left the Beeb behind the car, I used the side door  ) ....  :palm:

I have to tell you that polystyrene sarcophagus it comes in is no protection against the awful stomp of a Volvo 245 GLT  :bang:  :bang:

So, I was left with a 5" Floppy drive and a Cub monitor with nobody to talk to ....  :Doh:

Really snazzy straight dense grained timber though ...  :drool:

Dave








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Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #47 on: August 06, 2014, 07:13:20 PM »
Like PhilF my first experience with computers was with FORTRAN and punch cards handed to the university tech, and then waiting days for the result. I didn't do much of that, but it was required for one of my courses. I hated it!

When I got hooked was the late seventies when my calculator stopped working and I went to Radio Shack to buy a new one. They had (besides the Model 1 TRS-80, which I didn't even notice at the time) something called the Pocket Computer -- about the size of a wide calculator. It was programmable in a limited form of BASIC. I bought it and spent days working out routines for my design work at the time. It was great! No more waiting and punch cards!

Well it wasn't two months before I outgrew that and wanted more horsepower. The TRS-80 was too much money for me. But about that time Tandy came out with the Color computer with 4K of ram, used the TV as a monitor, and any cassette deck for storage, and I could afford that. In another couple months I had piggybacked 16K ram chips onto the 4K chips pulling in another address line, etc. Later I got an old IBM Selectric terminal, ripped the boards out of it, used an ASCII to EBCDIC conversion table in reserved memory and had myself a letter quality printer. That soon became old hat, so I built an LNW-80 with my own eprom programmer, etc, etc.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #48 on: August 08, 2014, 09:33:22 PM »
Being born in the early 1970s, I missed the so-called "golden era" of computers that some of the old fogies here will rattle on about from their comfy chairs.... punch cards, paper tape, etc. Golden era my ar*e  :lol:

As any fule noes, the real Golden Era started in the late 1970s with the introduction of the TRS-80, Sharp MZ-80K and Commodore PET computers; and went "mainstream", here in the UK at least, with the BBC B, Sinclair ZX-80/81 and Spectrum, the various Amstrads, the Vic-20 & C64.

My first ever contact with a computer was when a BBC B - complete with colour monitor and disk drives - "visited" our school (at the time, Cheshire primary schools had to time-share the only BBC it owned, I think it stayed for 1 or 2 weeks at a time). I was completely hooked, although I barely touched another computer until our Sinclair QL turned up sometime in 1984 (actually, it must have just tuned 30 years old sometime in the last couple of weeks).
Cheers!
Ade.
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Offline Bluechip

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Re: Adventures in old 80s computers.
« Reply #49 on: August 09, 2014, 04:59:17 AM »

Being born in the early 1970s, I missed the so-called "golden era" of computers that some of the old fogies here will rattle on about from their comfy chairs.... punch cards, paper tape, etc. Golden era my ar*e  :lol:


Don't forget the Noodle Picker  :lol:  :lol:

Dave
I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #50 on: August 09, 2014, 05:02:35 AM »

Being born in the early 1970s, I missed the so-called "golden era" of computers that some of the old fogies here will rattle on about from their comfy chairs.... punch cards, paper tape, etc. Golden era my ar*e  :lol:



You're barely dry behind the ears then Ade  :lol:
Andrew Mawson
East Sussex

Offline AdeV

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Re: Adventures in old 80s computers.
« Reply #51 on: August 09, 2014, 05:57:47 AM »
I will take that as a compliment - one has to take everything one can get at my age  :D
Cheers!
Ade.
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Offline DavidA

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Re: Adventures in old 80s computers.
« Reply #52 on: August 09, 2014, 06:05:05 AM »
In the eighties Bradford College was still using punched paper tape to feed the Bridgeport in the engineering department.

My earliest data storage was on audio tape cassettes. Do I miss that 'Screeeee' of data transfer ?  No ,  not really.

Dave.

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #53 on: August 09, 2014, 06:25:07 AM »
My first NC (not CNC) was a Moog Hydrapoint 1000. It used paper tape (or console) input but used air blown through the holes to read the tape !

No balls screws, or feed screws of any kind, positioning was done by hydraulic servos, there were binary coded sliding steel plates, the code being detailed by holes in the plates. The servo system homed in on the one hole that lined up through all the plates. Plate positions were set up with pneumatic activators through the paper tape, or air switches on the console.

My crowning achievement with it was to make a PC parallel port to 24 bit pneumatic interface using pneumatic pilot valves to mimic the paper tape (which was read in three stripes at a time hence 24 bits).

When I got it the free standing console umbilical cables had been separated from the machine by hack saw. They were 3" flexible conduit packed with 3 mm nylon pneumatic pipe. All the same colour and no documentation  :bang: Got there in the end.

Like the picture below, but mine had a tool changer carousel.

Did I say I like a challenge  :ddb:
« Last Edit: August 09, 2014, 01:07:02 PM by awemawson »
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Adventures in old 80s computers.
« Reply #54 on: August 09, 2014, 12:30:26 PM »
I'm sensing a certain parallel theme, Andrew, dating back a long way prior to the Traub.  :dremel:

I think you ought to quickly grab the domain name LazarusCNC.com and open for business!
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

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Re: Adventures in old 80s computers.
« Reply #55 on: August 09, 2014, 01:05:47 PM »
Steve, I just think it says 'MUG' across my forehead. I see these insoluble problems and convince myself that they are soluble given a bit of head scratching  :lol:
Andrew Mawson
East Sussex