On 30 Jul 2007 at 11:26, Ethan Dicks wrote: Don't forget the IM6100/PDP-8 based kits. I don't know how readily available parts are, but there is certainly a bunch of software written for that platform. On a side, but related, issue--has anyone produced a MicroNOVA kit? And is software available for that platform--or has it been locked up? Cheers, Chuck

Ethan Dicks wrote: What is a F20?

Thanks Ethan. I do have a good soldering iron, a non variable Weller that my father got in the trash at AT&T about 20 years ago. Still works very well, although it could use a new tip. I just finished recently soldering connectors onto a board for an old pinball machine I have, which now works very well. I have also built two kits from Ramsey, an electrocardiogram machine and a color organ. My soldering skill is pretty good I think. I'm leaning more towards the KIM at this point, mainly because of all the documentation, as well as the expandability. I'd like to have something that I can eventually program on a CRT and keyboard. On 7/30/07, Ethan Dicks <ethan.dicks at gmail.com> wrote:

Ethan Dicks wrote: Also pick up spare tips for your iron too, you never know when you'll need a new one.

Thanks for your advice, Tony. To address question #1, I'm honestly not too sure. I figure ha wih the early micros, there is documentation, where as something completely homebrew, there is little, if any. What I need to find is a good resource for electronic circuit design. I have a book called "How to Build Your Own Working Microcomputer" that I bought for under a dollar at a thrift store. I still need to finish it, but it doesn't seem to be much help in that respect. As for your second question, I would find it to be really fascinating to build a computer out of TTL, but again, I need some kind of resource to guide me through it. All my knowledge on electronic circuitry is very basic right now. My father, an electrical engineer, tells be that he couldn't even do it after six years of college(although, he graduated 20 years ago), so I'm not very hopeful that I could. Third, commercial software would be nice, but I don't need it. I would very much like to learn machine code. I figure that when I start college interviews in a year going toward something in the technology field, I'd like to have as much pre-knowledge of computer science as I can. I figure that there's no better way than to build and program a computer. It will take me a long time, but it would be worth it. In addition to my trusty Weller Iron, I do have an old Hitachi Oscilloscope and a Hewlett Packard Digital Multimeter. If absolutely necessary, I could try and find a logic analyzer, but thats one of those things I don't quite have the money for. Finally, I would most definitely use chip sockets. I don't want to risk heat damage to components if I can just solder in sockets and install the actual ICs later. It may not be as good for reliability, but it is better for ease of design and construction On 7/30/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:

2007/7/31, Dave Dunfield <dave06a at dunfield.com>: Wow(!!) :)

On Jul 31, 2007, at 11:30 AM, Roy J. Tellason wrote: That's absolutely correct, because most HR drones don't actually look for people who know anything about computers. If Joe wants to learn something about computers, as opposed to learning only what's guaranteed to get him a job in a suitly company, then I very strongly recommend that he pursue the path that he discussed above. Joe...As for your not being hopeful about building a TTL-based computer from scratch...The knowledge required to do it is readily available. If you REALLY want to do it, you can. Your father's assertion that he couldn't do it after six years of college is really irrelevant here...not many college EE programs teach anything about low-level computer architecture, and sadly, even fewer CS programs do. Learn about boolean algebra, learn about Karnaugh maps and other minimization techniques, learn about combinatorial and sequential logic...not only will you be able to design and build a TTL-based computer, but you'll end up knowing more about *computers* (as opposed to "how to install Microsoft products on PCs") than most anyone churned out by today's colleges. Further (also directed at Joe)...As you already very obviously know, it's actually possible for one to learn something without it being spoon-fed in a school. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007

On Wednesday 01 August 2007 18:18, Tony Duell wrote: Indeed. That sure sounds familiar... :-) TTL can be fun. I breadboarded a three-chip setup once with a 555, a 7400, and a 7474 that sequenced four LEDs. Stuff like that... Over and over again I see newbies struggling with what they're trying to do and what the simulation is telling them should be happening, which isn't necessarily all that connected to the real world. that's all they seem to cover in there--- m$ products, to a few different levels. Nothing beyond that. It's downright scary at times. As do I. :-) That's why I'm doing what I'm doing just now, a very non-technical job, but at least it's helping to pay the bills.... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Hi, As an assembly language programmer of some 29 years experience (not to mention some 31 years experience of electronics....I started young) I agree with that in spades! The last time I had a job as an assembly language programmer was 16 years ago, and even then those types of jobs were damn thin on the ground (now they're non-existant) - since every idiot these days seems to think "C" is the way to go....which it isn't.... :-( TTFN - Pete.

On Wed, 1 Aug 2007, Dave McGuire wrote: Got any good stories? I have one about a company that wanted a Z-machine to run on cell phones. At the time it seemed feasable, but then they started doing things like not paying the bills. -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

At 04:35 PM 8/1/2007, you wrote: Building and programming the Altair 8800, Altair 680, Kenbak, etc has done nothing but strengthen the skills I use at work too. I program AVR microcontrollers in both C and assembly. No matter what language, toggling in your code teaches (or scares) you to write efficient code. : ) Grant

On Thu, Aug 02, 2007 at 12:57:53AM +0100, Ensor wrote: When *I'm* interviewing prospective employees, I very much like to hear that they know their way around an assembler, even though most of our work is done in perl. If you've done assembler, you know programming from the *computer's* point of view, and I'm absolutely convinced that that gives you a significant advantage when it comes to debuggering, especially debuggering interactions with other systems, and a better understanding of the resources the computer makes available to your code. -- David Cantrell | A machine for turning tea into grumpiness Irregular English: you have anecdotes; they have data; I have proof

Hi, ROTFLAMO! I missed that when I read it.... :-) TTFN - Pete.

"Ensor" wrote: The last thing I want is 1600 posts to this list on a flame war about "c versus asm", so *PLEASE* don't respond to this over and over, but, as an anecdote, I recently hand coded a PPC algorithm in assembler, and spend 3-4 days working on it, got it all pretty and tight and when I benchmarked it, the hand written code was *SLOWER* than the C code. GCC is pretty good at generating fast code these days if - like any tool - you learn how to use it. Now I did hand-tune the c-code for a number of days, checking cycle counts on a simulator and moving things around to force the compiler to do things, did a lot of inline-ing and things like using constant array indexes and explicit if's where possible. So these days my feeling is that C is just a high level assembler, with a expression optimizer on top. don't get me wrong. I use assemblers all the time, for lots of different machines, but I was recently surprised to be beaten by a machine. I'll also note that this is a 32 bit machine. My comments only really apply to 32 bit machines with a reasonable pipeline and some amount of branch prediction. I've been able to do *much* better than the compiler writing assembler on super-super-scaler cpu's like the TI DM642. But trying to keep 6 ALU's going at one time can make your head explode. -brad

The book I certainly recoemnd is 'The Art of Electronics' by Horrowitz and Hill. It's expensive, sure. But I doubt you'll 'grow out of it' quickly. Put it this way, I consider I have some knowledge of electronics (and I trust eome others here agree with that), but I certainly don't know everything in that book. I still refer to it quite often. It starts from the 'what is a resistor' level, and goes on to microprocesors' It's a very 'practical' book, very little maths. There is also a 'lab manual' called 'The Student Manual for the Art of Electroics'. Certainly the second edition [1] contains a design for simple 68008-based microcmputer built on those solderless breadboard things [2]. There's no reason why you couldn't make it on stripboard or by wire-wrap, or... and/or expand it a little. I forget what's in the first edition of the book, maybe an 8085 or z80 baed design. [1] I like the books so much that I bought both editions of both books... [2] Personally I hate those things. Too many unreliable connections, too much stray capacitance. There's so much you can't do with them, you might as well solder the stuff up from the start! Thinking about it, I would suggest making youre first homebrew somputer using a normal microprocessor. You can get some experience of TTL circuitry my making interfaces for that. When you've got said experience, you will probalby be ready to have a go at ddesigning a processor. If/when you get that far, you might want to read some of the technical manauls and scheamtics for minicomputers, etc. Not to copy such a design gate-for-gate, but to see how things were done and learn a few tricks. I remember I learnt a lot from reading the CPU manual for the Philips P850 and then the one for the DEC PDP11/45 (Knowing what I do now, I'd not recomend starting with either machine, but it's what I had...) All I can asy is that I don't have any qulaifications in computing, electrical enginering or electronic engineering, and I've designed a simple processor. It's _possible_ I'm not sure how much good it will do you. Certainly the courses over here (UK) seem to have little, if any, hardware or machine code programming in them. But perhpas I've just been unlucky... TO be honsest, I doubt you'll get it all done in a year. This doesn't mean uoi shouldn't start, of course, and to be honest, I would consider what you learn from this to be a lot more valuable than the end product, and of course you'll be learning all the time so you will have something to talk to the interviewer about :-) I know that if _I_ was interviewing somebody I would be impressed if they were in the process of designing/building a computer., sicne I would realise all the practical stuff they must have picked up on the way. I've never overheated a chip by soldering it... But the real advantage of using sockets is that you can, say, pull a chip and force the pins to high and low states. You can pull your processor , ROM and RAM chips and check for shorts on the data bus with an ohmmeter. That sort of thing. One other point. Use decoupling capacitors. At least 1 0.1uF between power and ground close to each IC. That may be overkill, but I can assure you the cost of some disk ceramic capacitors is a lot less than your time in finding a nasty glitch. I speak from bitter experience here. -tony

Well done! This is true, and it's one reason for knowing how to use simple test gear effectively. I have debugged a lot of things that way, watching the brightness ot the LED to see if siagnal is stuck high, 50-50 (possibly a clock waveform) or something else :-) On the other hand, I once spend a sunday afternoon tracing a non-fault in the memory arbitration circuitry of a Whitechapel MG1, using a simple logic probe. I nearly went sane (!). The next day I sent off almost all the money I had and bought a LogicDart.... The reason I san non-fault is that the thing reported a multi-bit DRAM failure, and it appeared the CPU wasn't finding any RAM at all. That's why I thoguht it was a control/arbitration problem, not a memory chip failure. In fact, there was no fault at all. The boot ROM needed more RAM than was on the mainboard -- IIRC it needed a pair of memory expansion boards too. Nowehere was this mentioned... Why? I would have thought having known-good connections and low-impedance power and ground connections (neither of which tends to be the case on a breadboard) would be very helpful in only having to find the _real_ faults.

Hi, <GRIN> What, like a logic probe...? I don't actually have a logic analyser myself (annoyingly), and tend to reach for my logic probe long before I resort to digging out my 'scope. I find mine indispensible. If the OP is in the UK, then Maplins do a nice one for ?15 (which is less than I paid for mine back in 1980). TTFN - Pete.

Thanks for all the information everyone. I'm really looking into everything now, as far as building a computer from an off the shelf CPU such as a Z80 or 6502. One thing that has occurred to me is that I will likely need an EPROM Burner. Where can I get such a device for a modern PC? On 8/3/07, Chuck Guzis <cclist at sydex.com> wrote:

Chuck Guzis said: Not the best choice, IMHO, a better one you might find at www.willem.org. There are commercial clones as well, like the one from www.silvotronic.de (board, kit available through ePay for instance). I have bought a kit from them and they work fine. Another choice could be to use EEPROMs like 2816 or 2864/65; a very simple but useful device for the PC parallel port is from Chris Ward at http://home.freeuk.net/c.ward/6502/programmer.html. -- Holger

Chuck Guzis said: it does not make sense any more to user the three voltage EPROMs. Not only that they require quite a different programming method, the three supply voltages need to be applied in correct order (namely GND/-5V first, then +5, finally +12) otherwise they can easily be fried. Managed this more than once in the past, result was to rewire the circuit to use the less sensitive 2716s instead. -- Holger

On Aug 5, 2007, at 12:17 PM, Chuck Guzis wrote: Sorry to jump in, but I'd like to add my opinion. I have a few reasons why someone might use UV EPROMs. If you've got the right equipment, UV EPROMs are cheap, readily available, highly standardized, predictable, and generally pretty bulletproof. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007

Hi, That wouldn't be the "Sunshine" brand unit by any chance? I've got one of those too (along with their PAL programmer from around the same time) and it won't work in anything newer than an XT. :-( TTFN - Pete.

Why is that a disdvantage _on this list_? Surely original IBM PC/XT machines are not hard to find (are they?) and they're certainly repairable... -tony

Hi This is usually a problem of timing loops. One can often do some reverse engineering and either fix the timing loops or figure hope to write ones own code to control the hardware. Dwight _________________________________________________________________ Puzzles, trivia teasers, word scrambles and more. Play for your chance to win! http://club.live.com/home.aspx?icid=CLUB_hotmailtextlink

On 28 Aug 2007 at 20:40, Ensor wrote: I dug mine out to see what might be causing the problem. It looks pretty simple--the "bus" end is pretty much an 8255A connected through a PAL (unlabeled, I suspect this is what it is) address decoder. It shouldn't be that hard to suss out why it doesn't work on a faster CPU. A curious thing is that CMOS 4040's are used as some sort of address counter (24 bit? Would mean that the design could potentially handle some big EPROMs). It's surprising how much I've forgotten since I've last had the box out. It has 4 28 pin ZIFs on the EPROM module (gang programming, I guess) and a note I made somewhen taped to it: "Note: National 27256Q is programmed as half of a 27512A". I don't even think I have any 27256Qs anymore. Cheers, Chuck

Gordon JC Pearce said: Which is not really a fault of the Willem, but rather market decision. There is Linux support meanwhile for any toilet flush device, but there does not seem to be any need (in that a programmer adapts the available source code to Linux) to port that thing yet. Personally, I have been a Linux evangelist for long, but that ideology does not lead to anything rather than adding unnecessary complexity to life. The lesson that you don't fix screws with hammers but with an appropriate tool has yet to be learnt in computing. So I use Windows where suited best, and Linux in other situations. -- Holger

On Aug 5, 2007, at 4:16 AM, Gordon JC Pearce wrote: That in itself is a good reason to avoid them, in my opinion. I have two or three useless PC-based EPROM programmers sitting in various boxes in the garage. They're useless because the manufacturer has orphaned them (or just plain gone out of business) and I either lost the software, or it only runs under some release of Windows that isn't easily available anymore. (and I'll be damned if I'm going to have a Windows machine here just to run an EPROM programmer!) Anything worth doing is worth doing right. Get a standalone device programmer, not one that pretends to be a computer peripheral...or worse yet, a "Windows PC peripheral". With a real device programmer, you won't get locked into the whims of the manufacturer (at least not as easily), or worse yet, the whims of Microsoft. Having an important tool depend on an unreliably, proprietary operating system from one manufacturer who is well-known for sleazy business practices sure doesn't sound to me like a smart way to run. I used a Data I/O 2900 for many years, and I absolutely loved it. I recently replaced it with a Data I/O Unisite...a big beefy one with a hard drive. It's Good Stuff(tm) and can program pretty much anything. When designing or repairing something, I never have to stop and worry about whether or not I can program a particular device. These machines have floppy drives, and can deal with DOS- formatted disks (which most anything can write) and understand literally dozens of different file formats. They can also be remotely controlled via a *STANDARD* serial port, and the protocol is simple and openly documented. Like I said...anything worth doing is worth doing right. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007

Hi What I'd really like is information on programming some of the older Altera eprom logic arrays. Since these are obsolete, the software and hardware to program these is no longer supported. These are potentially great experimenter devices. With out and specs on programming they are useless. Dwight _________________________________________________________________ Booking a flight? Know when to buy with airfare predictions on MSN Travel. http://travel.msn.com/Articles/aboutfarecast.aspx&ocid=T001MSN25A07001

On Saturday 04 August 2007 07:51, Dave Dunfield wrote: Speaking of running standalone, that Ciarcia programmer I mentioned in another post apparently has such capabilities, having a single-digit LED display and a couple of status (?) LEDs as well, plus a pushbutton or two. I have *no* info on this mode of operating the thing, though. Anybody know where I might find some? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Tony Duell said: I haven't so far reached the maximum # of programming cycles for EPROMs in any experiment. *) As I recommended you might use EEPROMs instead of EPROMs mainly because of their moderate capacity (you won't need PC FLASH ROMs with 1MB or more for an 8 bit system) and because they don't need erasing in the UV coffin. *) Maybe your and my programming strategy differs; now with SW emulators for almost any old CPU being available ona PC, I tend to test my code in an emulator, often with single stepping first before I make a HEX file to burn it; even with EEPROMs - the old turnaround cycle of change a byte, program, insert and test how far it works is still too long even with RAM boxes. Admittedly, in the old times, without PC emulation, I did a lot of paper testing work first before burning the stuff into an EPROM; this discipline meanwhile degraded... -- Holger

On Saturday 04 August 2007 17:42, Tony Duell wrote: Agreed. Unless you have a pile of EPROMs handy... :-) I remember seeing one magazine article for such a device, but I wasn't that thrilled with the design of it. It used some sort of counter chips to step through the addresses of the target RAM, and wasn't very flexible in its approach to things. I started giving some serious thought to building one of those boxes, but never did finish it. Do you know of designs on the web? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

On Sun, 2007-08-05 at 12:29 -0400, Roy J. Tellason wrote: You want to try it with drum machines that store samples on EPROMs. Spend five minutes blowing the ROM, plug it in, turn on, hit the pad, "Byyoommf" - nah, that sounds rubbish, try again... Gordon

woodelf wrote: If you're talking about eprom emulators, "back in the day" I used to use a device called a "PROMICE". It was wonderful. I did a few different boot proms with one. Very handy. It was made by (I think) Grammer Engine. Try www.promice.com. But gosh, they do seem more expensive now that I remember... I looked on ebay and didn't find one, sadly; I did find, however an "ostrich 2.0" USB eprom emulator which looks nice. www.moates.net Apparently there is a large community of people out there hacking engine ECU's. who knew? :-) -brad

On Wed, 2007-08-08 at 01:24 -0400, Roy J. Tellason wrote: There's also Megasquirt, where you can buy the hardware platform as a kit, and download the circuit diagrams and firmware source code. Gordon

woodelf wrote: My first eprom burner was scratch built on a Apple II project card, a bit of address decoding logic, couple buffers, and a dac with an opamp. Look around a bit and I am sure you will still find cheap and cheesy solutions, PC cards or something off the parallel printer connection. BTW hacking the EEC IV in my 91 Mustang passes the 10 year rule just fine. You can find a hack of the Bosch Jetronic EFI brain on ebay right now, its the way modern hot rods work.

Roger Merchberger wrote: They also have a Bi-polar prom adapter for $110, but I am not sure anymore if I can get 74SXX's parts that it programs.

Grant Stockly wrote: Unicorn Electronics has 1702's still* listed for $4.99. * Most likly about 1/2 dozen left in stock.

----snip---- Writing 1702A's is tricky. You need to be able to switch the data lines by about 50 volts. If one is actually interested in building one from scratch, look on Al Kossows bitsavers.org under the Intel section. There is a manual for the MSC4 that shows a schematic for a MP7-02 1702 programming circuit. This board could be driven from most any digital I/O source. Dwight _________________________________________________________________ Learn.Laugh.Share. Reallivemoms is right place! http://www.reallivemoms.com?ocid=TXT_TAGHM&loc=us

I haven't followed this thread, nor intend to, but there's a book put out by Tab ages ago called the eprom project book or some such. A search on Amazon would probably turn it up real quick. You can build a rudimentary bit banger for next to nothing. Just thought I'd throw that in. I bought an old "blinken lights" style memory burner at a computer fair earlier this year. It's insanely cool. Haven't had time to play with it though. I requested information about it on here, but no one bit. Can't even remember the name of the manufacturer at the moment (Spectrum Dynamics maybe). ____________________________________________________________________________________Ready for the edge of your seat? Check out tonight's top picks on Yahoo! TV. http://tv.yahoo.com/

Hi, Funny you should mention that....mine is actually the "Micronta" probe which Tandy used to sell! Cost me about ?30 at the time, and that was in one of Tandy's sales (ISTR list price was some ?50). Still working perfectly, as is the analogue multi-meter I bought around the same time. BTW Tandy, in this country at least, turned "sales" into an art form....Christmas sale, spring sale, Easter sale, summer sale, autumn sale, the manager's blowing his nose sale.... :-) TTFN - Pete.

Dave McGuire wrote: ...which you can get away with because modern processors have a few dozen registers ;-) -- Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/ Help our electronic games project: http://www.mobygames.com/ Or check out some trippy MindCandy at http://www.mindcandydvd.com/ A child borne of the home computer wars: http://trixter.wordpress.com/

Dave McGuire wrote: Indeed. A few months ago, I built a machine on a breadboard. Not including the breadboard, the price of everything I used, *combined* was less than $50. Peace... Sridhar

Roger Merchberger wrote: Ta-da - I have a wall of wall warts. :) Note. Only about 3 but I hate them. Also one good thing... surplus pc power supplies for home brew.