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Location:
Land of Oz
Registered:
June 2004
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My really old computer
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Tue, 05 April 2005 12:06
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Hi,
I've just had a blinder and exceeded my own expectations in building a circa-1976 computer. 
This baby is running at a whopping 2.048Mhz and has 8K EPROM and 4K of RAM, a comms port and 3 parallel ports (8 bits each).
The CPU is an old National Semiconductor SC/MP processor, that is so crude and weak that it's almost fun trying to get it do anything useful.
Anyway, I've just finished completing the hardware build and it's currently running a comms test. Now the fun part begins 'cos I've got to develop a monitor/debug for it. However, that will have to wait 'cos some dudes on another forum want me to finish off my 6502 system first.
I think I'm better at doing maths in binary/hex/octal than decimal! I love this old shit. 
seeyuzz
river
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Location:
sydney
Registered:
August 2003
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Re: My really old computer
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Tue, 05 April 2005 12:14
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haha nice work 
the oldest comp i got is an atari 520ST and i actually found that at a garage sale. too bad i didnt ahve the $$ to buy the commodore64 there too
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Location:
Rockhampton QLD
Registered:
July 2004
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Re: My really old computer
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Tue, 05 April 2005 12:20
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so whats the go with these old computers, if they aint useful are they just fun to muck around with?
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Location:
Epping, Sydney
Registered:
April 2003
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Re: My really old computer
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Tue, 05 April 2005 12:30
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I have a Macintosh 512k 
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Location:
Land of Oz
Registered:
June 2004
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Re: My really old computer
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Tue, 05 April 2005 12:57
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Hi,
| 86DRFT wrote on Tue, 05 April 2005 22:20 |
so whats the go with these old computers, if they aint useful are they just fun to muck around with?
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Yeah, they're fun. I can get these old things to run more stuff, like servos, relays and other stuff than you can with the latest gear. Sure, the latest gear could do it, but you don't see too many add-in cards that can do the things that you want - and at a reasonable price.
Besides, it's good (and fun to sicko's like me I s'pose) to design from scratch a computer, build it, then develop your own OS all from nothing.
Most of these tasks (servo, relay control etc) are now done with microcontrollers such as the PIC and AVR chips, and they offer a single chip (or minimal chip) solution. I build and program these chips too, but I prefer playing with microprocessors.
I got some old Intel 8080 chips (circa 1974) to build my oldest computer. But, that's gonna have to wait until I clear out a few other projects and shit.
seeyuzz
river
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Location:
NSW
Registered:
October 2003
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Re: My really old computer
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Tue, 05 April 2005 13:16
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Is this stuff very technical? I work in a computer shop and have never heard of anyone doing this before.
Ah well good luck in your future old compter building.
Cheers,
Mitch.
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Location:
Land of Oz
Registered:
June 2004
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Re: My really old computer
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Tue, 05 April 2005 21:18
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Hi,
Yeah, I guess it's technical.
In a computer shop you get the various motherboards and bits and peices such as video-card, CD/DVD, RAM modules etc and you make a system out of these bits. If something doesn't work you do the swap-jockey bit to find the bad component and chuck it (or return it to the manufacturer, who probably chucks it).
I build my own systems from the actual chip level. This includes the design of the system, the chips required, the wiring between the chips, often I build the power supply from scratch also - but there are a lot of cheap PC/AT type power supplies so I often just use them. or a plug-pack for a small system.
If it doesn't work I got to trace my wires in case I've hooked up something wrong, or search for a bad chip. This usually involves using a logic probe/pulsar, CRO, frequency meter and multimeters to find the culprit.
After it's built and, from the hardware perspective, it is operational, I then have to develop my own software. For a general purpose system this means writing a monitor - sort of a silicon-operating-system that allows me to check/edit memory and the CPU registers, run programs, download programs. Then I usually add in debug software to provide breakpoints, single-step the system and such stuff.
I write the software on a normal PC that has cross-assemblers that convert my code to the appropriate CPU and I then download the code into the system. If it all works then I burn the code into an EPROM and fit the chip and she's all done!
I also repair/upgrade old pre-PC (ie 1974-1980) computers that were made by companies (ie not one's I built), such as System80, S100 stuff, Intel MDS and SBC, Exidy Sorcerers and other older stuff where they don't have GAL/PAL and/or surface mounted chips.
All this knowledge..... yet, for modern day stuff, totally useless!
seeyuzz
river
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I Supported Toymods
Location:
Casula
Registered:
January 2005
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Re: My really old computer
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Tue, 05 April 2005 21:25
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| Lench wrote on Tue, 05 April 2005 22:14 |
haha nice work
the oldest comp i got is an atari 520ST and i actually found that at a garage sale. too bad i didnt ahve the $$ to buy the commodore64 there too
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LOL I still have an old commodore64 in my shed.with the 500 upgrade and programs and all.
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Location:
Liverpool
Registered:
February 2005
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Re: My really old computer
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Wed, 06 April 2005 00:29
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I just looked up the word "geek" in the dictionary and there was a picture of Shane next to it...........Go figure. 
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Location:
Land of Oz
Registered:
June 2004
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Re: My really old computer
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Wed, 06 April 2005 00:37
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Hi,
| Farkurnell wrote on Wed, 06 April 2005 10:29 |
I just looked up the word "geek" in the dictionary and there was a picture of Shane next to it...........Go figure.
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Yeah.... but at least I'm an old school geek
I'm not into this new throw-away computer shit. Can't fix these down to the level of the old shit. SOrta like the newer cars as opposed to the older ones.
I can geek myslef and fix VCRs, TVs, amplifiers and heaps of electronic stuff.
If I could do intercoolers I'd be around your place like a shot, eat your bbq food, drink your beer and we can wax long and lyrical about the good ol' days,
seeyuzz
river - old school geek.... but never a nerd
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Location:
Liverpool
Registered:
February 2005
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Re: My really old computer
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Wed, 06 April 2005 02:30
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True Shane, it's always handy being able to fix all the gadgetry in the home to save a quid. I myself have kept the washing machine and fridge going well beyone their years. I fix most things electrical around the house but when it comes to cars, I can no longer do it, after years and years of maintaining all my cars it's painful having to pay someone else to do it.
Thanks for the offer anyway, shame you don't know your way round an intercooler like you do the old computers.
Cheers, Greg.
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I supported Toymods
Location:
Sutho/Hills NSW
Registered:
September 2002
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Re: My really old computer
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Wed, 06 April 2005 03:18
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| river wrote on Tue, 05 April 2005 22:06 |
Hi,
I've just had a blinder and exceeded my own expectations in building a circa-1976 computer.
This baby is running at a whopping 2.048Mhz and has 8K EPROM and 4K of RAM, a comms port and 3 parallel ports (8 bits each).
The CPU is an old National Semiconductor SC/MP processor, that is so crude and weak that it's almost fun trying to get it do anything useful.
Anyway, I've just finished completing the hardware build and it's currently running a comms test. Now the fun part begins 'cos I've got to develop a monitor/debug for it. However, that will have to wait 'cos some dudes on another forum want me to finish off my 6502 system first.
I think I'm better at doing maths in binary/hex/octal than decimal! I love this old shit.
seeyuzz
river
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reeeeeeeee mmmhoyyy
SEEYUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
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Location:
Adelaide, SA
Registered:
May 2002
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Re: My really old computer
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Wed, 06 April 2005 03:29
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river you are the sheik of geek!
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Location:
Madrid - Spain
Registered:
August 2002
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Re: My really old computer
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Thu, 07 April 2005 00:20
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So you finally got round to making that computer for the 18rg. Is this computer just gonna run the electronic ignition or are you gonna go for an electronic carby as well?
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Location:
melbourne
Registered:
February 2005
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Re: My really old computer
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Thu, 07 April 2005 00:37
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we got some massive one at school...
dont know the specs (but if u go near it u get told off )
its like a mitre wide but like 800 high n has a little screen its funny as.. oh and dont forget the light has blinking lights.
funniest thing ever.. makes me feal like my comp is worth having
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Location:
Newcastle, Australia
Registered:
March 2005
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Re: My really old computer
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Thu, 07 April 2005 06:52
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I have two Amiga 500's working at home here, good for nostalgia My main machine is a PowerMac G5 dual 1.8GHz, and I have a PC for games etc, P4 3GHz. The Amiga still has some of the best games!
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Location:
Melbourne
Registered:
May 2002
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Re: My really old computer
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Thu, 07 April 2005 09:48
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I bet im the only one with an Amiga A3000UX (runs system V unix and the aust defence force paid $4500+ for back in 1991 (moohahha i got my taxs back ) and an Amiga A3000T with a 68060 @ 50mhz and CV3D graphics card (OLD S3 pci chip basicly)
I also have an Amiga 1200 with an 68030 @ 50mhz with full burst cache man that was quick but burnt a hole in my desk it ran that hot and an Amiga 2000B with a 68040... i allways wanted a PPC card for one of my amigas such a shame commodore went bust 
Allan
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Location:
Land of Oz
Registered:
June 2004
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Re: My really old computer
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Thu, 07 April 2005 11:23
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Hi,
The 68030 is too modern for me to play and design with. I think I got one or two of the chips around, but I usually don't build/design anything more modern than the original 68000. THe 68000 is a sweet design, but their earlier 8-bit 6809 was pure genius. I got a few of those chips and I'm etching to get dirty with it.
I'm doing a 6502 design at the moment and things are looking grim and I'm gonna have to get out the 'scope on this baby to sort her out.
Gold28, yeah... I designed and built a comprehensive car-alarm using an old processor. It worked great for 10hrs before the battery was flat. I decided to keep electronics away from the car after that. Besides, the 18RG doesn't need electronics... it's just perfect the way it is - pure, wonderful, NA mechanical goodness.
seeyuzz
river
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