computer KO

wrote:


True. I missed the first DQ and mis-translated the second. Full flub mode.

Verily.

That's cuz you're a Sun of a b.

That went PSA on me, Don, unless it meant "Do what I meant, not what I said/wrote."
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    [ ... ]

    Exactly -- with the last half implied.
    Enjoy,         DoN.
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06:06:54 -0700 typed in rec.crafts.metalworking the following:

    "Kids these days! Why when I was a boy, we had to stack the electrons ourselves, by hand!"

    Half of it is the need to conserve resources doesn't seem to be there, half of it is software engineers having to justify their employment by making "improvements". I've been drawn into battle with Word 2010 - my SO has to use it, because the school is convinced it is "good". Her question boils down to this: am I here to learn about Creative Writing - or how to us MS Word?" I agree with her. What Win7 does to Wordpad is ... insane. Feature creep. I'm not looking for "Word Lite" so much as a bare bones word processor - I enter text, minimally edit it, minimally format it, save it and print it. No graphic options, no hyperlinks, no "ribbon" getting in my way.     I think I could make a mint with a WP package called "My Typewriter" - and that is all it does. "You can have any font you want, as long as it is Times New Roman, Courier, or Arial, in 8, 10 or 12 point."     Arrgh, it is way late, and I should be asleep - let alone merely in bed.

    thousand lines of batch file to "fake" a menu program. -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
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pyotr filipivich wrote:

Too bad you were too lazy to sort out the Positrons from the Electrons, first! I swear, it's a wonder you didn't destroy the planet when you were a kid! ;-)
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On my first homebrew I initially had to manually enter in the 32-byte bootstrap loader with the address and data toggle switches, so it could read in a Teletype tape.
Boy did I tire of that fast! First I wired up an octal keypad, then I scrounged two 5101 CMOS static RAM samples (256x4!) and kept them alive with NiCads.
Assembly programming lost its challenge when the 2Kx8 6116 came out. jsw
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    [ ... ]

    My first machine was an Altair 680b kit, which came with a monitor program in EPROM (a 1702 -- 256x8). But there was a jumper on board so if it were in one position, all the monitor would do on the CPU receiving the reset was set up the stack and then branch to a specific address -- 0x0000 IIRC. You could put the programs in the RAM, and examine the contents with front panel switches and LEDs. The original system came with all of 1K RAM (8 2102s) -- and while that could be strapped to live anywhere in the address space except where the EPROM or the I/O ports lived, the default was starting at 0x0000, and stretching all the way to 0x03FF. The stack was set to 0x00FF by default -- sometimes a nuisance.
    The clock was pulled down to a mere 500 KHz, because the 1702s would go no faster, and they did not implement a clock-stretching option to allow running at the full 1MHZ with the slow EPROMs. (There were sockets for four of them, and at one time I had all four populated.)

    The 16K SMB (Static Memory Board) made a big difference, along with a minimal editor and assembler, or an 8K BASIC interpreter from our long-time nemesis -- Bill Gates of Microsoft. :-) Eventually, the 1K got re-strapped to live well above everything else, to be a buffer and variable storage for the digital cassette tape interface which I made, which was fast enough to save either BASIC or the assembler/editor with an image of the whole of the 16K RAM, so I did not bother implementing the ability to save a program by itself. Save it embedded in whichever so it was easier to get started on the project the next day.
    Floppys, and later hard disks, with SSB's DOS-68/DOS-69 or OS-9 were a tremendous improvement. And I learned a lot of tricks from things like how the SSB OS stored files on the floppies, and kept track of unused sectors.
    Very different from either how unix did it, or the MS-DOS FAT filesystem.

    No real experience with the 6502 instruction set, for all that it was pretty close to the 6800 one. But my CNC lathe, an Emco-Maier Compact-5/CNC did it all with a 6502. No surprise that it is rather kludgy.

    They were useful substitutes for the 2Kx8 EPROMS to test how well a program would work there before committing it to EPROM.
    And my final memory card for the 6809/OS-9 system was a board of nothing but those and some glue logic, including bus driver/receiver chips. Ran a lot cooler, and did not oxidize the Molex bed-of-nails bus connectors nearly as rapidly.

    O.K. Sun used to use a CMOS RAM and a TOD clock chip with a coin cell potted into it to keep data -- for up to ten years. A lot better if you kept the system on full time, so the line power kept the memory and clock chip fresh. Two critical items were stored in there, the HostID, and the ethernet MAC address. If it lost those, you had to get a new one, and come up with fake values which were still valid enough so the OS configured itself properly for the hardware in the system board. :-) They now have SEEPROMS which need no backup power for that, or cards which plug in from the front with that, so you can switch licenses (if any) to a new box if the old one dies.

    Yep -- the lithium cells can deliver unpleasant surprises. We were using them to power some experimental night vision devices, and one of them exploded on a conduit bus box running around the room supplying outlets. It certainly startled the fellow in the room. :-) I don't know what extra hazards they might provide in a closed environment like that -- aside from the damage and sudden failure of critical equipment. :-)
    Enjoy,         DoN.
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A problem I didn't consider hard enough in advance is that a custom machine could run ONLY custom software. I had no clue how to structure a text editor and had to invent my own; same with the assembler and the paper & cassette tape storage system.
I put all the free space in the text buffer at the cursor, with the text before and after pushed into the ends, so that a typed letter went into the next free byte and DELETE simply backed up the cursor pointer. A side effect was that I could UnDelete EVERYTHING in free space by advsncing the cursor, whether or not I had entered it.
[start]This is the head[cursor]^%$#%*())_)(&%$#[next] and this is the tail.[end]
The assembler was built on a table of mnemonic codes with the numerical opcode as the index, which works fine for the simple 8080 set. It assembled line by line as an editor lookup and replace function, and also disassembled the same way, regardless of what was actually in the file. I had to watch closely and stop and reverse it when it spit out junk.
When I was done I had a large collection of useful editing primitives and subroutines. I still haven't seen a more capable macro facility than it had for reformatting text. jsw
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    :-)
    I used (for the digital cassette tape drive) the Motorola hex format, which was fine until I started doing random updates of data files, and the summer temperatures (no AC in the house at the time) changed the tape speed relative to the clock speed, so I wound up replacing a record with another with the same number of bytes, but shorter on the tape, so the next read hit the end identifier (s0 was the header, s1's were the data records, and s9 was the end of file), so it repeated the previous record which was still in the buffer. :-)
    Made floppies really nice when I got them. :-)

    Interesting!

    No practice of replacing the deleted character with a null? That would have lost the undelete function, but would have avoided gibberish. Did you start out by nulling the whole buffer before entering the first data?

    The 6800, which I started by hand assembling, had relative branches -- either intentional, or as a result of a test condition, which could go ahead 127 bytes, or back 126, and these had to be calculated from the target address to the current one (well, the location after the current instruction and its operand, which could be one byte or two, for something like comparing the index register to a constant). So, for hand assembling, you had to put in a marker until you had asssembled your way to the target location, then check whether the offset could be held in a single byte. If not, you had to go back, make the opposite test, and branch over a jump instruction which would take you to the final target. With all the code in a single 1702 EPROM, it pretty much *had* to be within range.
    Oh yes -- there was also a "direct page" addresses between 0x0000 and 0x00ff could be accessed with a single byte. The 6809 addeded a direct page register, so your current direct page could be anywhere in memory.
    But finally having an assembler to do the bookkeeping made life a lot easier. :-)
    And my first serious project was translating ASCII to Freiden Flexowriter codes -- a non-trival project. It took an entire 1702 EPROM for the look-up table, and a good part of another for all the code (I think -- it was done back around 1976 or so, so memory fades a bit. :-)

    Sounds nice.
    Enjoy,         DoN.
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I was given a digital cassette drive and warned that it might break tapes. Instead I built an analog FSK modem and managed the files manually from the tape counter on a standard audio recorder, with big gaps between files.
I looked into using a WD1771 floppy controller and fooling it into believing there was only one long track of 256 sectors, each containing 256 * 16 bytes. STEP would rewind the tape.

Nope, I assumed I wouldn't confuse whatever I had entered with random noise. The funny thing was that there could be four files in memory simultaneously and I could undelete text left by a previously opened one. It looked normal so I had to be careful.
As a prank I could make the computer appear possessed, undelete revealed eerie warnings the user hadn't typed. I got the idea from a programmer whose screensaver occasionally flashed REPENT, THE END IS NEAR!
That was disconcerting the first time you're walking past and it suddenly calls out to YOU!

I missed having short relative jumps that enabled relocatable code. All 8080 jumps were long and absolute. I had to link multiple programs by hand.
That's the main reason I discontinued working on the computer. It had served its original purpose of teaching me how to design computer hardware and I didn't really need to learn how to write an outdated operating system or imitate the controller that comes on a drive.
jsw
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    [ ... ]

    The tapes needed to have clear leaders so the BOT/EOT sensors would work -- or reflective tabs on the tape for the same function, depending. :-)

    The AT&T Unix-PC (a 68010 based machine) actually did that. Called it the "Floppy tape". It used a QIC-60 tape (DC-300 IIRC) and had four tracks. It reversed direction at the end of each track. I forget how many "sectors" it managed to get on there. IIRC, total size of the tape with that format was 23 MB, so 44,921 "sectors" total, or 11,230 per track. Not sure how it kept track of those. But it was deadly slow, because after writing a sector, it had to back up to re-read it (no waiting for the disk to complete a full revolution, there). I referred to it as a "head polisher". :-)
    The one thing which that was missing (for the day) was any kind of SCSI interface. There was one (prototype) in the hands of another member of the newsgroup dedicated to the system. It was called Unix-PC, 3B1, and 7300 -- the distinction between the latter two was that the 3B1 could handle a full-height 5-1/4" disk drive, while the 7300 only had room for the half-height.
    It was a great system for hardware hackers, after the AT&T "fire sale", since there was a book available which documented the whole of the hardware and the program's eye view of it.
    Maximum physical RAM was 4MB, as was the maximum virtual memory per process. Largest disk supplied with it was a 67 MB one, but information was spread around about a small hardware modification which would allow up to 190 MB (Maxtor or Priam full-height disks). The two limiting factors were the maximum number of cylinders, which was 1024 limited by the WD1010 controller chip, and replacing that with a WD2010 allowed going up to (and beyond) the biggest 5-1/4" MFM drive made. The other was a maximum of 8 heads/surfaces. A bit of wiring allowed accessing 16 heads instead. (There was a special jumper which told the OS that the mods were present.) Maximum of two drives (one external, of course). Floppy drive was built in and hidden behind the keyboard. It was a rather pretty looking desktop system -- a wedge beneath the monitor. A relatively primitive GUI called "UA". Green monitor. Built in modem and dialer, and software to keep track of Mr. Businessman's phone calls -- incoming and outgoing.
    And one of the *stupidest* defaults in the history of computing, especially given the target market. :-)
    The target market was the businessman. If you did not install an alternate editor (either vi with the optional development set, or a word processor), the default editor was ed(1). You click on a file and it fires up that editor, and loads the file into the editor. That one has no prompt, so you simply see a cursor blinking there. The only man page for it was the dead-tree one in the manuals for the (optional) development set. So -- Mr. Businessman is fumbling around with different keystrokes, leaving garbage in the file, and occasionally stumbling onto a command. He has *no* *clue* how to exit the editor, so he is likely forced into a reboot to get clear of it. :-)

    Yes -- a bit tricky.

    "Release key to detonate"

    :-)

    One of the reasons why I never went to the 8080. :-) I started out with a more friendly, and more regular instruction set. (Oh yes, there were a few undocumented opcodes, most of which did unreasonable things as the mirror image of reasonable things, like storing the contents of a register (8-bit or 16-bit) in the one or two bytes following the opcode -- a mirror of "Load Immediate" for A, B, or X.
    But the really weird one was one which got dubbed "HCF" (Hang and Catch Fire). It tri-stated the data bus, and sequentially put every address on the address but, repeating and repeating. (Kind of useful for debugging address decoding problems, as you got a train of square waves on each address line from fastest at the LSB to very slow blinking of the LED at the MSB. I actually burned an EPROM with a reset vector which pointed right at that instruction, doing nothing else -- for use when wire-wrapping various controller systems.

    I learned a lot from mine, and moved on to more complex systems, starting with the same CPU family -- and then cousins, uncles, and aunts. (6800, 6809, 68000, 68010, 68020). :-) The 68000 system was my first unix box -- v7 unix, as virtual memory was not supported until the 68010. These days, I'm using CPUs that I have no idea how they are doing what -- the UltraSPARC-III ones. :-)
    The 6502 is lurking in my little CNC lathe, and I really need to replace that with something smarter and with more storage capacity. Say an open-source LinuxCNC (used to be called EMC (Extensible Machine controller) before a storage company of the same name threatened lawsuits. :-)
    Yes -- way off topic, but beats political flame wars. :-)
    Enjoy,         DoN.
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wrote:

The company bought an 8080 microprocessor training kit for the lab techs to try out. I was the only one to get through it, and they gave me an 8080 chip set and some used wirewrap proto boards. We could sign out other components for home projects, code 20, as long as they were educational and relevant to the company's products; no HBO decoders.
The better source was parts we had experimented with, which became 'unclean' and had to be kept out of the production area so I took them home after lab cleanups, for instance the precision resistors I checked the megger against.
I found a simpler way to measure diode breakdown voltage with it. The diode and parallel voltmeter solidly indicate the meter's 10 Meg input resistance when the diode isn't conducting at low cranking speed. As I speed up the crank to increase the voltage the resistance begins to drop when the diode leaks. The DVM reading when the needle dips is the reverse breakdown voltage at a few microamps, an important and otherwise hard-to-measure parameter for expensive high-power components bought second-hand.
The 8080 was fine with ROM code but needed improvement to run a general-purpose PC, and soon received it as the 8085 and 8088. The register architecture, memory model and little-endian syntax conventions were definitely worth learning as they have survived into the latest processors http://en.wikipedia.org/wiki/X86 "Many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility."
"The instruction set is not typical CISC, however, but basically an extended version of the simple eight-bit 8008 and 8080 architectures."
It never bothered me that the registers weren't fully orthogonal, neither are my fingers. Limiting the capability of some registers allowed exclusively 1-byte opcodes.
jsw
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    Useful and enlightened.

    Hmm ... those resistors I would be tempted to mount on a wall hanging between two binding posts, with the legend
    Caution, Extremely High Impedance
in very visible letters. :-)

    Hmm ... my favorite for determining PIV was a curve tracer. The first one we had (Tek 575, IIRC) would go up to 1.5 KV in both directions. I've got a plugin for my 7000 series 'scope which doesn't go that high, but also doesn't take up a ton of bench space or a cart. :-)

    The 8088 was really the 8086 trimmed down to operate on an 8-bit bus, The 6809 had as much claim to being a 16-bit processor as the 8088 did.
    The fact that the original 8080 multiplexed the address bus through a single set of 8-bit pins is one of the reasons the S-100 bus is so scrambled. MITS made the original design before the address demultiplexer support chip was available, so they did it in random logic, and things came out from this cloud of chips in a weird enough pattern so they just routed each address pin to the nearest bus pin, with no attention to the logic of the layout. Same for the data bus, with 8-bits outgoing on one set of pins and 8 bits incoming on another.
    MITS' later machine, which I have, the "Altair 680b" had the address pins running in a logical sequence from one end of the bus connector (same 100-pin connector, but a different offset to keep someone from mixing boards from the two systems, which would not work. The data bus was a simple 8 bidirectional pins. Made it a lot easier to wire-wrap custom boards, such as the interface to the Oliver Audio optical punched tape reader, or the custom cassette interface. (And the expansion board for the bus was a vertical board which plugged into the 100 pin connector on the CPU board, and had three sockets for horizontally mounted boards. And a bit of examination showed that the traces continued to the top edge of the board, so you could solder another 100-pin connector on there, and plug in a board -- or another expansion board -- along the top. I used that for the Oliver Audio reader, which was not needed once the BASIC interpreter was loaded, in the pre-cassette days. I would take the cover off, plug in the board, transfer control to the punched tape loader which lived in another 1702A EPROM, start the reels running by pressing down on one of the tension-sense arms on the spooler (it was *fast* compared to the other ways to do things then), and once the tape reached the end, release the arm, switch the CPU to "halt", ease out the board, reclose the case, and switch back to run and hit reset to transfer control to the BASIC itself. (It offered me the choice of throwing away the trig functions if I didn't need them to maximize program space. (My first exposure to a commercial self-modifying program. :-)

    Well ... yes -- but the 6800/6809/68k family all use big-endian, which matches the "net order" for numbers. The SPARC family is also big-endian, and the Power PC (Mac for a while, and still IBM's AIX) had a software switch to decide whether it was going to be big-endian or little-endian -- normally set by the OS when it is loaded.

    Full backward compatibility, resulting in the rather klugy segmentation registers.
    Motorola bit the bullet when changing from the 6800 to the 6809, to give it a more powerful instruction set. And again, for the 68K family, which they kept with a standard instruction set (expanded as the part numbers grew).
    The 6809 had some features in the assembler which would emulate the instructions which had been dropped to make a more general set (e.g. replacing a number of set and clear bits in the status register with a single 8-bit word which would set them all in one instruction. This allowed assembling of any program for the 6800 into the 6809 which did not need to manipulate the stack and registers directly. This obviously excluded the monitor program, which needed to do a lot of that. But most other programs could be dropped into the assembler, and produce a functional (but slightly larger) program. The exceptions were things like one of the vendors' assembly-code implementation of something like nroff. The supplied full source code, but when I tried to port it to the 6809, it blew up. (It also blew up when I modified the banner to mixed case.) I later discovered that they had some code disguised by the comments. Which used negative offsets from the end of the program/beginning of data area to run a checksum on the banner so someone could not easily steal it. Also, there was another similarly hidden one which ran a checksum on the first checksum code block. Once I found those, and figured out the offsets, and checksum values, I was able to make it work -- until I moved to OS-9 from DOS-69. Lots of work running a disassmebler on the code and comparing it to the assembly source. :-)
    Also -- individual push and pull instructions were replaced by a single instruction which had an 8-bit operand in which each bit represented a register to push or pull, so a group would be saved or restored in a single instruction. (And as there were two stack pointers, it would always use the bit for the stack to save or restore the *other* stack.

    Yes -- which has held back Windows' progression for a long time, especially as long as they retained the ability to run all the old programs. :-) It also kept the number of security holes larger. :-)
    The 68K is a *nice* CISC, including single instructions which could access a two-dimensional array. You loaded one register with the starting address of the array, others with the X and Y dimensions, and yet another with how large an item was in the array (byte, 16-bit, 32-bit, or long strings. :-)

    The 6800 had some of those. The 6809 added some relative branch instructions which could hold the offset in the lowest 5 bits of the OPCODE. It also had the 8-bit offsets of the 6800, and full 16-bit offsets as well, to allow a fully position-independent program of any size which would fit in available memory. OS-9 took advantage of that, along with putting all the data on the stack so multiple invocations of the same program could co-exist. And *any* program in OS-9 could live in RAM or ROM -- your choice. You needed enough RAM to handle the stack and the data areas, of course, but the binary code could all live in ROM. (I had quite a bit of my system in ROM, but other parts could be loaded from disk at need.) Once a program is in memory, any number of invocation share the same space.
    Enjoy,         DoN.
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wrote in message

We wore out the Danger, 1 Million Ohms! joke quickly. The uninitiated avoided our ominous secret laboratory and techies knew better, so it had no target audience.

Mine too, but I don't have one at home. The spectrum analyzer already exceeds my quota for boat anchors. Even as the lab tech at Unitrode I didn't need a curve tracer often. I bought the megger to check the safety of old, disreputable motors and transformers and then looked for what else I could do with it. So far I've fixed one golf cart charger with its help. It showed that the transformer insulation was better than it looked and the NOS replacement ferroresonant capacitor could accept and hold 500V.
I can measure very low winding resistances with 1 Amp from a constant-current lab power supply and I think a Variac will find shorted turns, as abnormal magnetizing current.

I can't defend Intel's choices over Motorola's. I preferred the 68000 architecture too. The 8080 evolved from a calculator chip.
I have programming experience on the PDP8, LSI11, VAX, TMS9900 and its in-house TTL ancestor, 68000 embedded and in a Macintosh, PC\AT, and even the HP1000, designed a DRAM controller for the TMS320xx DSP, and I did a little with the PIC, MSP430 and Arduino. They'll all do the job, some aspects of it better than others.
The real question was which one(s) would be worth the effort to learn in more detail, both hardware and software. The Intel / IBM / Microsoft path was the widest, straightest and had the fewest thorns. The others were too narrowly focused.
I had to support the design engineer's religious preference, which was usually a PIC, TMS320 or an ex-front-office PC. They hogged the juicy Digital Signal Processor programming projects for themselves, but sometimes passed on the less interesting parts to me.
. I used that for the Oliver Audio

My bootstrap / monitor loaded in reverse order, top-down, so the final byte overlaid the Jump destination at the 00000000 reset location and started it running. Since assembled apps weren't relocatable one GO command started whatever was in memory. jsw
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On 22/06/13 15:08, Jim Wilkins wrote:

I had the pleasure of learning assembler on the 68000 as that was what my computer used and then we covered it on my Mech Eng course but as the computers in the engineering department were BBC micros they taught us assembler on the 6502. That was painful going in that direction and always a pleasure to get back on the 68000. The Motorola article about the design philosophy behind the 68000 is an interesting read, found it here http://www.easy68k.com/paulrsm/doc/dpbm68k1.htm , http://www.easy68k.com/paulrsm/doc/dpbm68k2.htm , and http://www.easy68k.com/paulrsm/doc/dpbm68k3.htm .
Never got on with Intel assembler and fortunately had to use it very little, largely just examining the odd bit of assembler, the last time being sorting out what checksum calculation a software provider had used. I found the checksum code in the exe by placing breakpoints and narrowed it down and found the code and as like much of the rest of their code they had wrongly implemented a CRC8. I was able to produce C code to mimic the error in new code so that new software would talk to the old hardware.
A chap I used to know was an extremely competent professional assembler programmer and said that the 68000 was his 2nd favourite processor, the most favourite being an esoteric silicon valley processor. All Intel chips were at the bottom of the list with x86 being at the bottom and every new x86 being added at the bottom. The sort of thing he used to do was when he was programming on a PIC he used a 68000 macro assembler to do it having written the macros to generate the PIC instruction set op codes, IIRC he admitted to getting one macro wrong but quickly sorted.

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    O.K. We had a few new victims every so often.
    How about the illuminated sign "Release to detonate" turned on by a pushbutton? :-)

    As a plugin for an already in-house Tektronix 7000 series 'scope, it doesn't take up much room. And it is really light compared to the 575 (which was tube-based, for all that it was for testing semiconductors. :-) And at something like $65.00 at a hamfest, how could I resist?

    They're nice for matching pairs of transistors out of a mixed bin of a given type. If you want a push-pull amplifier, better to have them matched.

    O.K. The only one I have is battery powered -- maximum applied voltage is 50 V, and it runs from a 67-1/2V battery and a 1.5V D cell.

    I wound up with a nice digital multimeter from HP which has four-wire measurement for really low resistances. (Another hamfest item.)

    4004, 8008, 4040, 8080 (in some order, starting with the 4004, and ending with the 8080 -- before they started making pretend 16-bit CPUs. :-)

    Nice mix of systems/CPUs. All of my assembly-language programming was 6800/6809 (and a 6802 for a minimal system to interface some friend's PET computers to Diablo HyType I daisy-wheel printers. (It just *had* to be IEEE-488, of course. :-) I also used that for interfacing a Fluke HV supply with binary input to selct the voltage to a HP desktop computer (9826 was it?) 9815? Somewhen back in that period. :-)

    Better than nothing. I got to pick my CPUs at work, to play to what I knew well at home. :-)
    [ ... ]

    O.K. The 6800 put the reset vector in the top of address space (normally in ROM), and usually dumped you into a monitor if a general-purpose computer, or directly into ROM for an embedded one.
    The move from the PDP-11 instruction set to the 68000 one found a lot of bugs in BSD unix utilities. A lot of uninitialized pointers, which thus were pointing to address 0x00000. The PDP-11 apparently just shrugged and let you do it, but the 68000 slapped your wrist -- hard -- because that was where the various interrupt vectors lived. Fine for the OS to change them at need, but absolutely verboten for an application program. :-) So, over the years, as various applications dumped core, they found more and more of those uninitializd pointers. :-)
    Enjoy,         DoN.
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"DoN. Nichols" wrote:

7*** plug ins are dirt cheap on Ebay at the moment. I bought a 7B85 for a $5 starting bid & shipping to see just how hard it would be to duplicate the frame. Others are starting at $1. & shipping. A 7A19 Vertical amp just sold for $1.
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    [ ... ]

    This may mean that the power supplies in the 7000 mainframes are starting to die off. I had to replace some electrolytics in mine to keep it going. (I've also got newer, lighter ones, but without the versatility that the plugins give. :-)
    There's a 7CT1N (my curve tracer) for $650.00 right now -- but that includes a 7613 'scope mainframe a 7A18 vertical and a 7B53A horozntal plugin as well. Also a 'scope cart. And the mainframe is one with storage, too.
    But no 7CT1Ns by themselves. :-)
    Enjoy,         DoN.
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"DoN. Nichols" wrote:

The only 7000 series I ever used was a 760x with a spectrum analyzer & the CATV preamp plugin. I had to repair the power supply in it, back in the early '80s. That was fun, with no manual.
I currently have these Tek items:
Scopes: 324 ($20 + a half pound of mud to remove after it was dug out of the ground in a scrap yard), a 453A, and the 2465A.
Vectorscopes: Two 1720 (bought for $10 each)
Waveform monitors: One RM529 ($200, bought in the late '80s) Two 1730 and two 1730D (bought for $10 each)
Video test set, which is a waveform monitor & vectorscope in one package. It may be the only thing Tek ever built with two CRTs . ;-)
Video waveform generator: TSG170 ($40)
7B85 Delaying Time Base Plug-in ($5)
I also have a military scope built by Magnavox (from Freecycle), and another waveform monitor built by HP. ($35, bought in the late '80s)

Save a search, if you really want one. I have 15 saved at the moment, and had a few others that finally turned up what I wanted at an affordable price.
Here are a few current searches:
Tektronix 324      Tektronix 7A
Tektronix 7D      Tektronix 7K      Tektronix 7L
I had one for a Fluke FLUKE 8920A 20 MHz True RMS voltmeter that got me three damage meters for $30. One meter was made out of the pile, instead of paying $250-800 for one.
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    Easier today. Almost all Tek manuals can be downloaded from a number of sites.
    Bad caps?
    760x would be 100 MHz bandwidth (IIRC), with two vertical slots and one horizontal one -- and no storage capabilities. (That '0' would be a '1' or '2' depending on how fancy the storage was. :-)

    [ ... ]

    O.K. *That* one is for a 7000 series mainframe -- and one of the later ones, IIRC.

    Was that one which was made as a clone of one of the 5xx series Tek 'scopes?

    [ ... ]

    I *have* one -- from a hamfest perhaps ten years ago. I think that it cost me something like $65.00 at the time. A friend more recently got one after seeing mine.
    As for the other Tek stuff:
    7623 storage mainframe
    7913 storage mainframe with power supply problems still.
    7603 out in /dev/barn -- I think that it also needs power supply     work.
    7B53 timebase (horizontal)
    7B52 timebase (horizontal)
    several single and double vertical input preamps which I won't     bother to go down and look up to list. :-)
    7D?? (digital analyzer (16 bits in) and the 7F?? display formatter to go with it.
    454 (portable scope, no plugins, but bandwidth to 150 MHz at the probe tip. It was all solid state except for the CRT, and Nuvistors on the two vertical channels and the one external trigger channel. Made it a *lot* more rugged than the 453 (FET front end) which we zapped a time or two with hour HV stuff in the lab. :-)
    RM-454 (same thing in a rack-mount adaptor).
    22?? (lightwight portable scope, no plugins, something like 60 MHz bandwidth I think.
    Lots of probes.
    And a third-party spectrum analyzer plugin for the 7000 which needs fixing.
    [ ... ]

    HP DVM -- rack mount with lots of resolution.
    Portable modular HP DMM with GPIB deck in between. Also     serves as a frequency counter.
    GR Strobotac (nice for speed measurement of machines, and     watching cycling machines to see what is going wrong)
    GR decade boxes.
    GR decade attenuator boxes.
    GR sound level meter and calibrator.
    Fluke model 27 Handheld DVM (I had a 77, but the continuity beep was too high pitched for my hearing, so I sold it.
    Various lab type power supplies, including three Power Designs 2005 units. (Dial in voltage with four knobs from 0.000 to 9.999 and a switch to add 10.000 volts to it. Crystal oven around the voltage reference. With current limit.
    Power Designs 3650 (I think -- 0-36V, 0-5A With current limit.
    And certainly a number of other things that I've forgotten, (Including a relatively new function generator.)
    Oh yes -- Tek TM-500 mainframe/power-supply and two plugin (so far) -- digital multimeter, and three output power supply -- 5V, and dual outputs 0 to +15 and 0 to -15V which track with a common knob, or independent adjustment. Nice for mixed logic and op-amp circuit development. :-)
    And the TM-500 lives on a shelf below the 7623 on a cart beside my electronics workbench.
    Enjoy,         DoN.
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wrote:

221? 5mhz
Had one stolen. I actually miss the hell out of it
http://www.metrictest.com/product_info.jsp?mfgmdl=TEK%20221
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