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Re: [cosmacelf] cosmac elf question

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  • Dave Ruske
    Emulators are limited in a way that a real ELF isn t: you can wire anything to a real ELF. An output that blinks a light can also drive a speaker or be
    Message 1 of 9 , Dec 8, 2004
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      Emulators are limited in a way that a real ELF isn't: you can wire
      anything to a real ELF. An output that blinks a light can also drive a
      speaker or be connected to a relay to run a motor, light a furnace, or
      fire a thruster on a satellite. Similarly, inputs can be receive data
      from photoeyes, gyros, thermocouples, limit switches, etc.

      Of course, with an ASCII input and output device like a teletype, you
      can do more desktop computerish sort of things such as simple text
      editing or interactive software development. Add a graphics chip, and
      you have the makings of a primitive video game system, like RCA's old
      Studio II.

      On its own, the ELF is a very simple computer that excels in teaching
      computer fundamentals. The hardware is fairly straightforward, and the
      1802's instruction set is about as clean as a microprocessor gets,
      making machine language coding accessible to beginners.

      The 1802 may not be suited to rendering special effects for the next
      bad Star Wars sequel, but with a bit of imagination there's quite a lot
      that it can do, and has done.

      Dave

      On Dec 8, 2004, at 7:52 PM, craigsherenow wrote:
      > hello i am working on building a elf my self but right now all i
      > have is a emulator but i was wondering other than making lights
      > flash what can you do with a elf
      > thanks
      > craig
    • sbirdasn
      ... Wow, what an open-ended question. Answer: Whatever your imagination can dream up. But seriously, the 1802 is an excellent processor for doing simple
      Message 2 of 9 , Dec 8, 2004
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        --- In cosmacelf@yahoogroups.com, "craigsherenow"
        <craigsherenow@y...> wrote:
        >
        > hello i am working on building a elf my self but right now all i
        > have is a emulator but i was wondering other than making lights
        > flash what can you do with a elf
        > thanks
        > craig

        Wow, what an open-ended question.

        Answer:

        Whatever your imagination can dream up.

        But seriously, the 1802 is an excellent processor for doing simple
        control and monitoring functions that do not require lots of sub-
        millisecond response times.

        It all depends on what kinds of hardware you decide to hook up to
        your Elf.

        My VIP manual (a glorified Elf with 1861 built in) gave a good list
        of fun ideas, but is woefully incomplete.

        Here are a sample of what was found on page 26 of the VIP user manual:

        4. Monitor burglar alarm switches.
        5. Monitor water level and temperature in fish tank and regulate
        automatically.
        6. Measure motor speed with photocell.
        7. Monitor and control experiments in home, school, or lab. Use video
        display for real time bar graphs of multiple variables.
        8. Provide a crystal-controlled, programmable pulse generator, clock,
        or timer.
        9. Provide a programmable sequencer for light shows, advertising
        displays, holiday lighting, etc.
        11. Model railroad controller.
        12. Battery-operated toy or robot controller.
        13. Detect tape-player tones and control slide projector.

        Some of my own ideas:

        A. Battery recharger/cycler.
        B. Maze mouse. OK, a type of robot, but with a specific goal. How
        clever can you get with very limited memory space and processor speed?
        C. Model Rocket telemetry/data logger- Altitude, acceleration,
        rotation, temperature, etc.

        Now, you could do all of the above (and much more) simply by using a
        more modern microcontroller. Modern uC's are quite fast, have lots of
        I/O built-in, often including A/D converters and even D/A in some
        cases, numerous timer/counter/PWM hardware, UART's, etc.

        Some even include LCD drivers to make the task of display easy on the
        designer while keeping the current consumption down.

        The down side to modern uC's is that they are in many cases rather
        difficult to expand on, as only some expose some part of their
        internal buses to allow easy hardware expansion (often at the cost of
        1/3-1/2 of their inherent I/O).

        Your basic Elf is a dream to expand on. High fan-out CMOS logic, with
        high noise immunity and low current draw keep power consumption down
        and interfacing to real-world sensors easy.

        You can really get down-on-the-metal understanding of what's going on
        inside your project, since all of the hardware interfaces are exposed
        for your examination. Development tools are at best rudimentry, but
        the typical Elf is quite simple and slow. Even a logic probe can
        provide vital troubleshooting information, if an oscilloscope is not
        available. Depending on your version of Elf and possible
        modifications, single-stepping, cycle-stepping or even single-
        clocking an 1802 is possible.

        And don't get Lee started, man, he's got all kinds of fun ideas.

        So, you were saying: What can I do besides blink lights?

        Gee, I dunno, use your imagination. And have fun doing it. It's
        really about the journey, not the destination.

        Tony Naef.
      • rileym65
        Hello Craig, depends on what you hook it up to, for example, i have built an interface to connect my elf to an IDE disk drive, and wrote an operating system to
        Message 3 of 9 , Dec 8, 2004
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          Hello Craig,
          depends on what you hook it up to, for example, i have built an
          interface to connect my elf to an IDE disk drive, and wrote an
          operating system to use it, or, with a little bit of extra hardware
          you can make a simple rs232 port so that you can connect up a terminal
          to it,,,i have some software that would work from rom that would allow
          you to write FORTH and LISP programs. What you can do with the Elf is
          only limited by what you hook up to it and your imagination. :)
          Beautiful machines these Elfs! :) so easily expandable and adaptable
          to whatever you want.
          Mike

          --- In cosmacelf@yahoogroups.com, "craigsherenow" <craigsherenow@y...>
          wrote:
          >
          > hello i am working on building a elf my self but right now all i
          > have is a emulator but i was wondering other than making lights
          > flash what can you do with a elf
          > thanks
          > craig
        • erd_6502
          ... with a elf ... Yes, but a common one these days. Almost everyone I showed my Popular Electronics Elf to had the same question - what can you _do_ with it.
          Message 4 of 9 , Dec 8, 2004
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            --- In cosmacelf@yahoogroups.com, "sbirdasn" <sbirdasn@y...> wrote:
            >
            > --- In cosmacelf@yahoogroups.com, "craigsherenow"
            > <craigsherenow@y...> wrote:
            > > i was wondering other than making lights flash what can you do
            with a elf
            >
            > Wow, what an open-ended question.

            Yes, but a common one these days. Almost everyone I showed my
            Popular Electronics Elf to had the same question - what can you
            _do_ with it. For me, the task was about building it much more
            than running it (since I have more than one 1802 machine already).

            One of my work buddies described it as "building ships in bottles".

            Considering how limited the I/O is with the 1976 design, I am
            inclined to agree. Either the MicroElf or the Elk 2K are of
            substantially greater "use" - with 32K of SRAM, ROM, easy to add
            mass storage, etc.

            > My VIP manual (a glorified Elf with 1861 built in)..

            I'd say the VIP is more than a glorified Elf... it's more akin to
            the 6502 SBCs of its day... video, keypad, couple of expansion slots,
            etc. Not that an Elf _couldn't_ have those things, but by the time
            you added them, the VIP would probably have been cheaper in the
            first place. To me, the VIP is more of a simple general-purpose
            computer, and the Elf is more of a demo board - good for learning,
            but limited enough that it might be better to start with a different
            platform (same CPU) than to add everything one needs to turn it into
            a general purpose computer. Not to say it's impossible, but that
            another tack might be easier and perhaps cheaper.

            A friend of mine did turn his Quest Elf into the control center for
            a home-made robot by just adding one input and one output port
            (on Radio Shack 44-pin prototype cards)... probably a dozen CMOS
            chips and some Darlingtons to drive the relays for the motors. He
            didn't expand or latch the memory, so it would eat away at its own
            program as it stored stuff above 0x0100 (meaning it started storing
            new stuff at 0x0000 and up...)

            So it's true with minimal effort, one can take the basic Elf
            design and do interesting things with it, the original board
            can do little except count, etc., _except_ for the Q LED... I
            think one of the coolest applications I've seen for that is a
            darkroom timer - one toggles in the exposure time, and presses
            the IN button to control the exposure - the control itself is a
            simple relay driven off of a transistor off of the Q line. A
            trivial upgrade to the Elf, but a real-world use... presuming
            you are into B&W photography.

            -ethan
          • Lee Hart
            Hi Craig! Welcome to the list. ... Good heavens! This is like asking what you can do with a microcomputer! To most people, computer means the PC sitting on
            Message 5 of 9 , Dec 9, 2004
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              Hi Craig! Welcome to the list.

              craigsherenow wrote:
              > other than making lights flash what can you do with a elf?

              Good heavens! This is like asking what you can do with a microcomputer!

              To most people, "computer" means the PC sitting on their desk. For all
              their power, they are really just an appliance. It only does what the
              manufacturer wants it to do, and it only runs software that someone else
              wrote. Now, there is a *lot* of hardware and software out there for it
              -- maybe all you care about. But, what if you wanted to do something
              different?

              Think of a PC like a radio. A super-duper radio, that can receive any
              station, anywhere in the world! You can listen to thousands of programs!
              Even save them, to listen later, again and again! Any music you want,
              any time, as many times as you want it! What reason could there be to
              have anything else?

              But, what if you are musician? You want to *create* new music, not
              listen to someone else's music. You want a musical instrument, like a
              guitar; not a computer. Now, a guitar is vastly simpler than a computer.
              But in the hands of skilled artist, you can make great music, much
              better than that which comes out of the tinny speakers on your computer.

              The 1802 is like this -- it's a musical instrument for "playing" with
              the hardware and software. You use it to do things that are NOT done by
              conventional PC. By being vastly simpler than a PC, you can get right
              down to the most basic level. Things become easy that would be horribly
              difficult and complicated on a PC.

              So... what'dya want? A radio or a guitar? :-)
              --
              "Never doubt that the work of a small group of thoughtful, committed
              citizens can change the world. Indeed, it's the only thing that ever
              has!" -- Margaret Mead
              --
              Lee A. Hart 814 8th Ave N Sartell MN 56377 leeahart_at_earthlink.net
            • sbirdasn
              ... Exactly. It s the journey, not the end result that we love about Elf s and their kin. There is little that an 1802 can do that a modern microcontroller
              Message 6 of 9 , Dec 9, 2004
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                --- In cosmacelf@yahoogroups.com, "erd_6502" <erd_6502@y...> wrote:
                >
                > --- In cosmacelf@yahoogroups.com, "sbirdasn" <sbirdasn@y...> wrote:
                > >
                > > --- In cosmacelf@yahoogroups.com, "craigsherenow"
                > > <craigsherenow@y...> wrote:
                > > > i was wondering other than making lights flash what can you do
                > with a elf
                > >
                > > Wow, what an open-ended question.
                >
                > Yes, but a common one these days. Almost everyone I showed my
                > Popular Electronics Elf to had the same question - what can you
                > _do_ with it. For me, the task was about building it much more
                > than running it (since I have more than one 1802 machine already).
                >
                > One of my work buddies described it as "building ships in bottles".
                >
                > Considering how limited the I/O is with the 1976 design, I am
                > inclined to agree.

                Exactly. It's the journey, not the end result that we love about
                Elf's and their kin. There is little that an 1802 can do that a
                modern microcontroller can't do more simply and with fewer parts, and
                lots cheaper. Even the 1802's static current consumption is not out
                of reach if you are selective in your uC choice.

                Heh, that's no different than the little box with a blinking light.

                Q. What's it for?

                A. It just blinks.

                Q. That's it? (puzzled look)

                A. Well, yes (he just doesn't get it, shrug).

                > Either the MicroElf or the Elk 2K are of
                > substantially greater "use" - with 32K of SRAM, ROM, easy to add
                > mass storage, etc.

                But this is mostly a matter of convenience. It's hard to build
                a "true" stock Elf with only 256 bytes of RAM these days. Assuming
                you hook up all of the address lines, that is. My parts box has 2Kx8,
                8Kx8, and Oh_my_goodness,_what_to_do_with_all_these_
                extra_address_lines'sized SRAM chips. Nearly anything I do these days
                is going to have gobs of memory to play with. It's just too easy.

                Back when Elf's were young, RAM was hard to come by, and expansion
                RAM projects rapidly get out of hand for wiring complexity. Now,
                adding some RAM is as simple as two chips, and boom! Massive amounts
                of RAM.

                Even a wire-wrapped Elf with lots of RAM is a cinch these days, while
                very painful/expensive when they first came out.

                > > My VIP manual (a glorified Elf with 1861 built in)..
                >
                > I'd say the VIP is more than a glorified Elf... it's more akin to
                > the 6502 SBCs of its day... video, keypad, couple of expansion
                slots,
                > etc.

                So what does that make the Netronics Elf II with pixie graphics
                standard and its five expansion slots? Now if you include one 4K
                memory board and a Giant board, you now have more memory than a stock
                pre-assembled VIP (2K RAM).

                The Giant board gives you a mini-monitor program with all of the
                basic features of the VIP, including tape read/write routines. Total
                cash outlay if you were willing to do the assembly yourself was not
                much more than the VIP's cost, like %10 more or thereabouts. Sounds a
                lot like a VIP's capabilities to me.

                > Not that an Elf _couldn't_ have those things, but by the time
                > you added them, the VIP would probably have been cheaper in the
                > first place.

                But that's what a VIP is- a cost reduced Elf w/Giant board & newer
                RAM chips.

                > To me, the VIP is more of a simple general-purpose
                > computer, and the Elf is more of a demo board - good for learning,
                > but limited enough that it might be better to start with a different
                > platform (same CPU) than to add everything one needs to turn it into
                > a general purpose computer. Not to say it's impossible, but that
                > another tack might be easier and perhaps cheaper.

                And which Elf's fit into which catagory? Sounds like picking nits
                here. All Elf's are in essence "Single Board Computers", with varied
                expansion capabilities. The VIP was only middle of the road for ease
                of expansion.

                Now if you were a developer, then RCA had the CDP18S012 COSMAC
                Microtutor II, which is essentially an RCA-brand Elf in developer
                clothing. The microtutor comes with toggle switches, hex display, and
                256 bytes of RAM. Still sounds like a SBC to me though.

                And what about RCA's CDP18S020 COSMAC Evaluation Kit? The Eval. kit
                was much more serious: 4K RAM, ROM monitor, extra 32-byte RAM for
                register dump, etc. with an Assembler/Editor option, ment to be run
                from a serial terminal/teletype. Now that matches your SBC definition
                better than the more modest VIP.

                And thus was the beauty of the 1802-based Elf design. Those who had
                to scrimp, could roll their own, and cut every corner in the process
                to keep costs in line. Those who could afford it, would buy the PCB
                versions. I think all of the early PCB Elfs have some form of
                expansion capabilities.

                Besides, the VIP is still a Weisbecker brain child design. Knowing
                that the original hex displays were one of the big cost items in the
                Elf design, and recognizing that many Elfs ended up with pixie
                graphics and hex keypads anyway, he simply took advantage of the
                1802's excellent hardware/software trade-off capabilities and melded
                the two into a rather elegant and cost effective solution. RAM was
                now cheaper and higher density, so was more plentiful. Oh, and Chip-8
                along with many of the first VIP games were ripped off from the soon
                to be tanking Studio II design.

                There is little difference between the Netronics Elf II and a VIP in
                terms of chip count or the amount of glue logic used. If you were to
                smoosh a classic Netronics Elf II, Giant board and RAM onto a single
                card, a VIP-like design would be the logical result. The materials
                cost is about the same either way if you include keypad, pixie
                graphics, and some kind of expansion. If you are going to do Tiny
                BASIC stuff, then a Giant/memory equipped Elf II is what you need
                anyway.

                Weisbecker did have the advantage of being able to get mask
                programmed 1832's essentially at cost since he worked for the same
                company that made them.


                All of the above, including the eval. kits are very Elf-like, if you
                include what people on this forum have been doing with their Elfs-
                old and new.

                Now for marketing reasons, the VIP was pushed as both a games and
                learning machine, but it clearly has its roots in Elf-like
                capabilities. The fact that it came with an on-card 8-bit I/O port
                shows that experimentation was a central theme for VIP's design too.

                Cost-wise, if anything, the VIP suffered from RCA's marketing and
                infrastructure overhead.

                When RCA responded to my letter about VIP kits in November, 1978, the
                VIP kit (CDP18S022) was $219, without speaker, video cables, I/O
                chips or edge card connectors. While fully assembled versions
                originally were $249 for the VP-711 (CDP18S711), with everything
                populated including empty sockets for the second 2K of RAM.

                I was a poor high school student who washed dishes for my spending
                money and went the kit route.

                Two years later, probably due to pressure from Netronics and Quest,
                the VP-711 version cost $199. While a new gutted VIP (VP-111) sans
                power supply, blue plastic cover, I/O port chips, and only 1K of RAM
                sold for $99. For those writing histories, they should note that the
                VP-111 was a later model, and had the dark keypad, not the white
                keypad like the earler and more fully stuffed version.

                >
                > A friend of mine did turn his Quest Elf into the control center for
                > a home-made robot by just adding one input and one output port
                > (on Radio Shack 44-pin prototype cards)... probably a dozen CMOS
                > chips and some Darlingtons to drive the relays for the motors. He
                > didn't expand or latch the memory, so it would eat away at its own
                > program as it stored stuff above 0x0100 (meaning it started storing
                > new stuff at 0x0000 and up...)
                >
                > So it's true with minimal effort, one can take the basic Elf
                > design and do interesting things with it, the original board
                > can do little except count, etc., _except_ for the Q LED... I
                > think one of the coolest applications I've seen for that is a
                > darkroom timer - one toggles in the exposure time, and presses
                > the IN button to control the exposure - the control itself is a
                > simple relay driven off of a transistor off of the Q line. A
                > trivial upgrade to the Elf, but a real-world use... presuming
                > you are into B&W photography.
                >
                > -ethan

                Well, finding "doable" things with an Elf is exactly what appeared in
                the pages of "Popular Electronics" over the years. There were
                numerous articles on hardware expansion: RAM, I/O ports, Pixie
                graphics (that *was* an add-on for home brew Elfs, remember?), etc.

                Game programs and other software was also included in the mix.

                Lots of Elfs graduated from toggle switches to hex keypads, too.

                One project was an 1802-based model rocket altimeter data logger.
                Though it wasn't considered an Elf project at that point for
                packaging reasons.

                Tony Naef.
              • erd_6502
                ... My dad built one of those before I was born - a 3x3 grid of neon bulbs driven by an RC network, powered by a *large* battery (like 3 C cells fastened
                Message 7 of 9 , Dec 10, 2004
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                  --- In cosmacelf@yahoogroups.com, "sbirdasn" <sbirdasn@y...> wrote:
                  > Heh, that's no different than the little box with a blinking light.
                  >
                  > Q. What's it for?
                  >
                  > A. It just blinks.
                  >
                  > Q. That's it? (puzzled look)
                  >
                  > A. Well, yes (he just doesn't get it, shrug).

                  My dad built one of those before I was born - a 3x3 grid of neon bulbs
                  driven by an RC network, powered by a *large* battery (like 3 C cells
                  fastened end-to-end, with snaps rather than passive contacts). All it
                  did was blink.

                  > But this is mostly a matter of convenience. It's hard to build
                  > a "true" stock Elf with only 256 bytes of RAM these days...

                  True, but I happen to have a bit of older SRAM. I specifically used
                  that to build my Popular Electronics Elf - I was going for an exact
                  reproduction, not a modern functional equivalent. Those are just as
                  easy to build, but in my case, that wasn't the point.

                  > So what does that make the Netronics Elf II with pixie graphics
                  > standard and its five expansion slots? ...
                  > Sounds a lot like a VIP's capabilities to me.

                  I guess because I'd been playing with 1802 since the days of the P-E
                  article and the Quest PCB, I don't think of the Elf-II or the SuperElf
                  when I think of an Elf. Those are certainly much like a VIP.

                  > But that's what a VIP is- a cost reduced Elf w/Giant board & newer
                  > RAM chips.

                  I'd say the difference starts with the fact that the VIP depends on
                  the 1861 as its primary way of getting data to the human, that the VIP
                  doesn't use the LOAD mode of the 1802, thus its dependence on the code
                  in ROM to do anything useful. Those are fundamental differences
                  between the VIP and an Elf. Even the Elf-II uses LOAD mode from its
                  keypad. The VIP keypad is strictly a run-time I/O device, and there
                  are no hex or binary displays of the data bus as with the Quest Elf,
                  the Elf-II, the Super-Elf, et al.

                  > I think all of the early PCB Elfs have some form of
                  > expansion capabilities.

                  The Quest Elf has a 32x8 PROM socket; that's it. My buddy who made a
                  robot controller out of his installed a wire-wrap socket to easily tap
                  off the necessary control lines and data bus to add his I/O ports. I
                  think everything after that _did_ have expansion capability.

                  > Cost-wise, if anything, the VIP suffered from RCA's marketing and
                  > infrastructure overhead.

                  Sure... I never got one until _years_ later (1984?) when I found one,
                  with manuals, 4K, blue cover, etc., for $35 at the Dayton Hamvention.
                  Snapped it up right away!

                  > ...VIP kits in November, 1978, ... (CDP18S022) was $219...
                  > fully assembled versions originally were $249 for the VP-711
                  > (CDP18S711)...

                  I remember they were way out of my reach, but I didn't remember how
                  far. Also, at the time, I didn't have a B&W monitor, so the 1861
                  would have been useless to me, as would a VIP itself (since it rather
                  depends on video).

                  > I was a poor high school student who washed dishes for my spending
                  > money and went the kit route.

                  I got my Quest Elf PCB when I was about 14 or so, and spent months
                  scrounging up the parts to stuff it from Radio Shack, and our local
                  electronics dealer that happened to handle RCA parts.

                  > Two years later, probably due to pressure from Netronics and Quest,

                  > Well, finding "doable" things with an Elf is exactly what appeared
                  > in the pages of "Popular Electronics" over the years. There were
                  > numerous articles on hardware expansion: RAM, I/O ports, Pixie
                  > graphics (that *was* an add-on for home brew Elfs, remember?), etc.

                  Yes... I happen to have an original mag with the 1861 add-on. I built
                  my P-E Elf last year with that from the get-go (since it was a common
                  enough add-on, and I happened to have a spare 1861... what I'm still
                  looking for is a genuine 74L00 for the oscillator circuit - I have a
                  74LS00 there for now).

                  I agree that I'm probably splitting hairs. It's hard to make
                  generalizations about the early 1802 designs since there were so many
                  of them. I still put the VIP in its own class, perhaps because it was
                  less of a hobbyists version than any of the ones that appeared in the
                  pages of Popular Electronics magazine. I happen to have the Elf-II
                  issue, complete with PCB layout... I frequently entertain the notion
                  of burning that one myself - I've done small boards, but _that_ one
                  would be a hard one to do... I think the only thing that has really
                  kept me back was that I don't have a good source of compatible keypad
                  switches - everything else is somewhat easy to get, even if it is $5
                  or more for some bits.

                  -ethan
                • sbirdasn
                  ... newer ... VIP ... code ... Yes, fundamental differences, but still sensible changes in the evolution of small experimenter computers. A manual LOAD mode is
                  Message 8 of 9 , Dec 10, 2004
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                    --- In cosmacelf@yahoogroups.com, "erd_6502" <erd_6502@y...> wrote:
                    >
                    > > But that's what a VIP is- a cost reduced Elf w/Giant board &
                    newer
                    > > RAM chips.
                    >
                    > I'd say the difference starts with the fact that the VIP depends on
                    > the 1861 as its primary way of getting data to the human, that the
                    VIP
                    > doesn't use the LOAD mode of the 1802, thus its dependence on the
                    code
                    > in ROM to do anything useful. Those are fundamental differences
                    > between the VIP and an Elf. Even the Elf-II uses LOAD mode from its
                    > keypad. The VIP keypad is strictly a run-time I/O device, and there
                    > are no hex or binary displays of the data bus as with the Quest Elf,
                    > the Elf-II, the Super-Elf, et al.

                    Yes, fundamental differences, but still sensible changes in the
                    evolution of small experimenter computers.

                    A manual LOAD mode is essential for a CPU with no off-line storage or
                    any kind of bootstrap ROM. It is useful for small sequences of bytes,
                    but painful beyond several hundred bytes. Same goes for toggle switch
                    data entry, binary discrete data/address displays, etc.

                    Now add several thousand memory locations, and the threshold of pain
                    is too great for the average user, no matter how enthused.

                    With lots of memory, some kind of off-line storage is more than just
                    a convenience, it's a necessity. You *could* battery-backup a 256
                    byte Elf, but retention time was only decent if you had CMOS RAMs.
                    Expanding to larger memory sizes was typically done with NMOS parts,
                    and they were power hogs. It would take a massive battery pack if you
                    expanded to say, 4K of NMOS 2114's (400-500 mA or more).

                    So, now you have a boat load of minimum system requirements:

                    1. Hex keypad entry.
                    2. Full hexidecimal address display.
                    3. Hexidecimal data display.
                    4. Cassette storage.
                    5. Some kind of primitive monitor for data entry/examination.
                    6. Graphics display standard.
                    7. Keep hardware costs down.

                    Now, do you still need LOAD mode? You do if you have to enter a jump
                    address at the beginning of RAM to gain access to the monitor program.

                    But why force the user to go through such hoops and jumps? Programs
                    are going to get much more complex, so there is going to be a lot
                    time spent using the monitor program. Why not make it easy to get to
                    by the user? Thus, the VIP's automatic running of the monitor ROM
                    *every* time, which checks for something special to force entry into
                    the monitor when the RUN switch is flipped. Many RCA development
                    systems have a "RUN-UTILITY" switch to do this sort of thing. Yet
                    another switch cost.

                    Creating lots of Pixie graphics programs? Single stepping won't work.
                    Have to use some other form of debugging. Getting access to the
                    internal CPU register contents would be very handy now.

                    The VIP answered all of the above concerns in a rather clean manner:

                    1. Video is close at hand -> free display of address and data.

                    2. Scan keyboard in software to keep keypad cheap. Monitor program
                    just spends most of its time spinning anyway. Clever reuse of keys
                    keeps the keypad size at 16, no need for a really custom keypad or
                    additional switches.

                    3. Easy access to monitor program, so LOAD mode and single-stepping
                    is a luxury. Drop them. Saves a bunch on switches and status LEDs.

                    4. Built-in cassette data/program storage, so memory protection is
                    not so important. You can recover a errant program's scribbles on
                    itself with just a few keystrokes.

                    5. Borrow that big brother developer card's trick of dumping CPU
                    register contents to RAM. It can just be squeezed into the modest
                    sized ROM, so go for it.

                    6. Add one 8-bit I/O port. With all that memory, some built-in I/O
                    makes sense. Handy debugging tool in a pinch too.

                    And the VIP managed to cram all of its monitor functions in a svelte
                    0.5K bytes of ROM. And much of the contents was reusable for user
                    programs too. A rather clever bit of code, if you ask me.

                    Now look at these new ELF creations. Plentiful EPROM storage makes
                    powerful monitor utilities and remote program loading a snap. I would
                    guess that the typical ELF2K will spend little time in LOAD mode. How
                    often will single-stepping be used? Hard to say, but if Tiny-BASIC,
                    FORTH, or other ambitious programs are running, seldom, if ever.

                    > I still put the VIP in its own class, perhaps because it was
                    > less of a hobbyists version than any of the ones that appeared in
                    the
                    > pages of Popular Electronics magazine.

                    True, it is going in new directions, but remember, the video game
                    craze was exploding at that time. Many of us jumped at the chance to
                    make our *own* video games, even if they were primitive compared to
                    arcade versions. Saved money in the long run too, if you could wean
                    yourself from emptying your pocket change into those quarter-hungry
                    consoles. ;)

                    More substantial computers were quite out of our league in those
                    days. Elfs and VIPs were pretty much the only game in town for a cash-
                    strapped would-be computer owner. There were many other single board
                    computers much more capable in those days, but by the time you added
                    displays and other necessities, the cost was just too much. Even
                    going the VIP route, I was forced to buy my own cheap 9" B&W TV and
                    an RF modulator kit. Taking over the only other TV in the house just
                    was not going to fly long term.

                    Even a few years later with the introduction of Atari 800's and C-
                    64's, the initial costs of those machines were too rich for my
                    pocketbook. It was several years later before prices came down and I
                    could afford such machines. Even then, it took a year or so before I
                    could afford adding a disk drive for my Atari.

                    Ah, the memories. Those were the days...

                    Tony.
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