NABU PC – A 1984 Z-80 Computer You Can Buy Today

Want to hack on brand new 8-bit 1980s hardware? Until recently you needed a time machine, or deep pockets to do this. All that has recently changed with the NABU PC. A retro machine that can be bought brand new for $59.99, (plus shipping) no time machine needed.

[Adrian] has one in his Digital Basement, and breaks it all down for us. The NABU PC was a Canadian computer.Β  Designed to connect to the cable TV network, the standard system had no internal secondary storage. You read that right; the NABU used the cable network to download and play games, view documents — just about anything you’d want to do with a computer. Cable modems back in the 80s — maybe someone did have a time machine?

Unfortunately, the NABU network failed. Not due to the PC’s hardware, but because the cable system back then was not designed for bidirectional data. While the NABU PC did see a limited release in Canada, was never widely successful. When production was shut down, the machines couldn’t be liquidated, as they didn’t do anything without the network. So in the warehouse, they sat, until this month, where can find them being sold on eBay.

So what’s inside a NABU? It starts with a Z-80 CPU sporting 64 kB of RAM. A TMS9918 handles video, while a General Instrument AY-3-8910 does the sound.Β  There are also two UARTs. An 8251 for serial io to the keyboard and joysticks, and a high-performance UART chip to handle comms with the network adapter. The keyboard is loaded with good old ALPS switches, and [Adrian] found it rather impressive.

That’s all well and good, but what can you actually do with a NABU PC? Right now, not much. The ROM software comes up and looks for the network adapter, then complains when it doesn’t find it. This means it’s hacking time! An army of retrocomputing enthusiasts are already working on bringing back the NABU computer. Check [Adrian]’s video description for all the documentation links, and check here on Hackaday for the latest updates!

This isn’t our first time watching this sort of liquidation — remember the HP touchpad?

62 thoughts on “NABU PC – A 1984 Z-80 Computer You Can Buy Today

    1. YouTube videos appear to show the TMS9918A VDP. It’s better than the TMS9918 but still has the 2 colors per 8×1 pixel horizontal segment limitation. MSX1 game artists learned to so some pretty good graphics with that limitation. A full bitmap mode where every pixel could be individually set to any of the 15 colors or transparent would have required more VDP RAM, and DRAM was very costly in the 80’s. So TI didn’t bother to give the 99nnA VDP series a full bitmap mode because nobody would’ve used it in a home microcomputer.

        1. Al Charpentier and Charles Winterble almost got it right in the VIC-II. They allowed you to scroll screen 7 pixels up/left for free, but that 8th pixel required copying 2000 bytes to manually shift text and color ram :( Big oversight considering C64 can only copy ram at <120KB/s with all the tricks. Smoothly scrolling screen at full framerate will use all of the CPU on the PAL model just to copy data around with nothing to spare for game logic.
          What was missing was another register to define starting character offset. That way scrolling 8 pixels up would just require rewriting 40 characters/80 bytes, sideways 50 bytes. NES had that and more.
          Very late after C64 heyday scene coders started discovering fiddly tricks forcing VIC-2 to do exactly that. VSP ("Variable Screen Placement", also called DMA Delay), FLD, Line Crunch, AGSP ("Any Given Screen Position"). Its all ugly, exploiting silicon bugs, prone to causing ram refresh corruption and computer crash if done badly/having unlucky hardware, and invented way too late. Afaik the only C64 game that ever used it is 1993 "Mayhem in Monsterland" and it looks and plays FANTASTIC, pretty much Sonic the Hedgehog lever great. :(

    2. The TMS9918 can pass through a video signal, which allows it to do text overlays. A rather handy function for a box intended to hook up to a cable service. I don’t know if the V9938 preserved the pin for that functionality. (and not all the TMS series VDPs had it either, the TMS9928/A and TMS9929/A did not)

      Sega’s VDP in the Sega Master System and Game Gear is a step up from the V9938 in some ways while being architecturally similar. And the Sega Genesis/MegaDrive’s VDP is even more advanced, and maintains compatibility with the SMS (but not the GG).

      I think my ideal fantasy Z80 PC would be a TMS9918 overlay on top of a Motorola 6845 PC-style CGA. Assuming I even want composite output in this day and age.

      1. “I think my ideal fantasy Z80 PC would be a TMS9918 overlay on top of a Motorola 6845 PC-style CGA. Assuming I even want composite output in this day and age.”

        The overlay functionality was used for Laserdisc support at some point, too, I think.

        CGA.. Oh my goodness. Don’t you mean Plantronics? I wrote a few programs for CGA and I find it sort of interesting, yes..

        On a real CGA or an SVGA card (ISA bus) in emulation mode, all the palettes and intensity modes are accessible via the register writes. Playing with them is/was sort of fun, too.

        However.. TV out on CGA is NTSC/60 Hz only, no PAL/SECAM compatibility. MSX VDPs existed in various flavors, by comparison. Allowing pass-through of 50 Hz signals. Which wouldn’t be compatible with 60 Hz CGA. :(

        Ok, while RGBI output exists on CGA, matching monitors do not anymore. Even SCART TVs with analog RGB inputs are on decline. And VGA, too.

        Also, Composite CGA was like Apple II video and was the most eye-friendly of them, I think. Unless you used a monochrome video monitor, hah. ;)

        CGA also has various shortcomings, I think. A 4 color, 640×200 mode is/was technically possible with the CRTC, but the address decoding on the IBM CGA was incomplete/defective and prevented it.

        Then, the memory consumption for an 4 colour image is/was 16KB, but the addressing has a bug, thus taking up 32KB instrad (same data is doubled/mirrored). AFAIK.

        There’s a semi-popular 640×400 mode monochrome mode on Olivetti M24 that’s a CGA superset, also. It was supported by 16-Bit Windows and GEM. And implemented by various PC emulator boards for Atari/Amiga. Unfortunately, the Motorola 6845 cannot display 400 lines..

        1. “Unfortunately, the Motorola 6845 cannot display 400 lines..”

          Sorry, I have to correct myself here.

          What I was thinking of was both CGA and 400 lines in progressive mode (400 lines on TV would require interlacing).

          The 6845 was also used for MDA/Hercules, which use 720×348.

          And a C64 emulator for Hercules exists that uses a non-standard 640×400 mode.

          Here’s more information about the CRTC:

    1. Actually, you did not.. I went and picked up mine in person this afternoon, and the seller has nearly a thousand of these left.. he is just having a hard time processing the mass influx of orders in the last few days, so he turned off the listing while he can get caught up.

      He said that as of right now, he has 440 orders pending, some of which are for multiple units, so around 500 units to label and ship.. then he will relist the remaining ~1000 in smaller batches so that he can keep up with the demand.

      1. There was only 71 sold in his last batch… if you look at his prior listings you will see that there was a batch of 200 that sold out, and another batch of 298 that also sold out..

        The boxes are fairly large and heavy, depending on where you are in the world, I can see there being a $45 shipping charge. He is just one guy selling these out of his garage.. not some big warehouse with a shipping receiving department and big courier discounts.

    2. Surplus sales of Nebraska has some in stock on their website for $16 plus shipping, selling them as metal project boxes.

      The description makes no mention of the keyboard, but it sounds like the machines are new and everything else is included.

        1. “The logic module includes 4 socketed chips: a TR1865CL-04, a full duplex UART, a SC87253P 8 bit microprocessor, a N8X60N FIFO I/O controller and a pre-programmed ROM. The remainder of the parts on this board are numerous 74LS series logic ICs.”

          Wait a minute. So the main unit RF box is just a modulator. The really interesting part, the cable modem, is this “NABU adaptor”. Im much more interested in someone reverse engineering this cable modem part than another Z80 computer!

          1. It’s essentially a modem. It converts the encoded data sent down the TV cable to a serial bitstream which the NABU computer loads via the high speed serial connection to the cable adapter.

            The original intent was to have two way communication but in most places NABU was available the cable systems never implemented that. So they had to publish program schedules where a selection of software would be made available and you’d select from a menu. If the cable company wasn’t “showing” the game you wanted to play, you couldn’t play it.

            Think of it as Netflix for software, with a very small selection at any time, and the selection changes several times a day. I could see using that as a way to not have games available after school when students should be doing their homework.

            With two way communication the system could theoretically have all the software available all the time. The menu transmission would list all the programs. When the user selected one the NABU would send a command to send back the selected program. But that would require switching hardware installed by the cable company to direct the selected software to individual NABU boxes. A pretty tall order for mid 1980’s analog TV cable systems. If they ever had that working I’d bet it was very costly for a cable company to install.

    1. Of course your phone will still work, assuming you mean an Android device. Anything that relies on Google infrastructure/services will have limited functionality at best, though.

  1. Are there any hints that the cable-modem could coexist in a modern network? i.e. if a cable-network engineer wanted to play ball, could they carve out some frequences for NABU without taking down DOCSIS?

      1. Surplus sales of Nebraska sells cable modems for this as “Builder’s Project Boxes”. Google:

        >surplussales The logic module includes 4 socketed chips: a TR1865CL-04, a full duplex UART, a SC87253P 8 bit microprocessor, a N8X60N FIFO I/O controller and a pre-programmed ROM. The remainder of the parts on this board are numerous 74LS series logic ICs.


        >surplussales Builder’s Project Boxes

  2. It’s the TMS9918A, not the TMS9918. The A has some more features, and was the “A” in the TI-99/4A.

    Now if the F18A MK2 FPGA enhanced TMS99xxA replacement was available, the NABU would be an ideal candidate system to develop a new ROM to take full advantage of the video chip.

    There’s a video on YouTube posted by a guy whose father was apparently involved in the development of the NABU or peripherals for it. He’s working on NABU hacking and showed video he took of old computer parts he threw out when his father died, one item was a floppy drive controller for the NABU. At least the video he has of it is clear enough to provide some clues about what hardware was used in the floppy controller.

    1. You’re right, I think. Though the article at says that the “A” was dropped in later revisions for some unknown reasons.

      Personally, I’m a bit depressed that the system is limited to a 9918/A.
      So many missed opportunities..
      If it had a slightly newer 9938 VDP, which is backwards compatible, it would be possible to port SymbOS over to it.

      The 9918 was the reason that the MSX had games on ZX Spectrum level. With all the stuttering (scrolling issues) that goes with it.

      MSX2 standard used a 9938 VDP and the platform became a big hit in Japan.
      Unfortunately, here in Europe, MSX1 and the 9918 essentially ruined the MSX’s name.

      Which is a shame, because its heart, the Z80, was a very capable processor.
      Combined with a powerful VDP and various sound chips, it could really prove that it’s capable of handling multimedia.

        1. TI99/4A? I heard there was a huge bottle neck, because the main CPU had to access RAM through the VDP.. Later versions changed this, I vaguely remember.

          Anyway, I don’t mean to judge. Never had one myself. πŸ€·β€β™‚οΈ Closest I had was TO7/70. It had a weird video chip, too, with a similar graphics “quality”. And it had a light-pen, at least, which was fully supported in all programs.

          My father, however, had a TI99 or TI99/4A when it was new that he got rid off very quickly after he bought it.

          When I asked him why it’s nolonger here, he said it was essentially a useless machine. Nothing could be done with it, cassettes (cartridges, he meant) were needed for about everything.

          The manual and various schematics for its peripherals are still in the house (cellar)..

          1. The TI-99/4A was a very capable computer, when expanded with the Peripheral Expansion Box, 32K RAM card, RS232C/PIO card, floppy controller and 2 or 3 floppy drives. Plug a speech synthesizer into the right side then the PEB cable into that and it’s ready to run just about everything.

            The computer had 16K of video RAM and 256 bytes of CPU RAM. A strange setup but when used with Extended BASIC or programs compiled from assembly language it was very fast.

            What was extra clunky about it was TI created a programming language for their Video Display Processor. It was called Graphics Programming Language or GPL. (Long before the GNU Public License.)

            They were attempting to create a GPL CPU to execute GPL programs directly. Well that was a flop so they shoehorned their TM9900 16 bit CPU into the 8 bit computer. But they left the console BASIC in GPL. So console BASIC programs were translated to GPL *then* to 9900 machine code.

            Extended BASIC went directly to 9900 code so it was much faster. IIRC some of the cartridges produced by TI were in GPL so they weren’t as slow as console BASIC, only needing to be translated from GPL to 9900.

            The main cartridges one needed were Terminal Emulator II, which provided console BASIC with access to the Speech Synthesizer. Nobody used its serial terminal emulation. Editor/Assembler for writing and compiling assembly language programs and for loading and running compiled programs – especially all the cartridges that got ripped to load from disks. Disk Manager for managing files on floppies and formatting disks. Extended BASIC for writing and running Extended BASIC programs.

            Most of the time it would be E/A in the cartridge slot. There were several 3rd party disk manager programs it could load from disk.

            The biggest stumble TI made was never producing a double density floppy controller. They left that up to the aftermarket. TI’s original Disk Manager cartridge didn’t do double density, but they did release a Disk Manager II cartridge that worked with double density 3rd party controllers. There is a mod for the TI controller to make it use 720K 3.5″ or 5.25″ 80 track drives in single density to use them as 360K. IIRC some of the 3rd party disk manager software can copy between those disks and normal 40 track double density 360K, with a 3rd party controller of course.

            The most genius part of the TI Home Computer was how they *didn’t* try to put support for anything and everything into the console like many other 1980’s micros. The console operating system knows nothing about any hardware other than what is built in plus the joysticks and audio cassette.

            What it does is on power up it scans a section of the memory space divided into ‘ports’ where peripherals can connect. Built into the peripherals is a ROM containing a Device Service Routine, what we call a driver for PC and Mac systems. The DSR seamlessly patches into the console system, providing all the commands, device names etc to operate the peripheral. For example, if your system doesn’t have an RS232C/PIO card installed and you attempt to send to PIO (parallel input output) you get a standard error message. The PIO isn’t there and the console doesn’t know *what* isn’t there. Same with trying to access DSK0 (or DSK1 etc) without a floppy controller.

            Remove a peripheral and all the code for it is gone, like it was never there. That made the system extremely flexible and open to building all kinds of new hardware nobody at TI could have envisioned. It just needs a DSR that works with the method it uses to extend the core operating system. One such item was a USB 1.1 and Smart Media card. Unfortunately that was introduced only a month or two prior to the demise of Smart Media, when Olympus pivoted to XD Picture Card. There was a floppy controller with MFM hard drive support, and the ForTi MIDI card with four of the sound chips used in the console. A user group called SNUG designed and built a whole set of PEB cards that when all plugged in eliminated the need to have the TI console.

            Unlike so many other 1980’s Micros, the TI didn’t have any port or connector “for future use” in a future that never came for them. TI made it future proof, then killed it dead in a literally last minute decision while they had a prototype of the 99/4A’s successor waiting to be rolled out at a big trade show.

            One big problem was internal to Texas Instruments. Their microchip division was charging the Home Computer division *full retail prices* for the CPUs and all the other TI made chips. Nevermind they were all the same company and at worst Home Computer should have been using their most generous wholesale chip prices in their bookkeeping.

        2. I forgot to thank you for the link of that cute demo. Thanks a lot!
          Just did finish reading the comments on, there’s even a photo of a physical cartridge! πŸ™‚πŸ‘

        1. It depends on the point of view, I guess.

          Your comparisons are a bit on the extreme to my taste, I think.

          a) the Famicom was the *THE* game console. Not just in Japan, but in most developed countries. Even Russia loved it (Dendy in the 90s).

          Merely Europe and Brasil had a heart for its later rival, the Sega Master System. Which had a somewhat better VDP than MSX1 or TI99/4A, by the way.

          b) the NEC PC-98 was a platform similar to the IBM PC in the west. Memory layout was different (and got CBUS vs ISA), but it also ran on x86 processors and a special vetsion of MS-DOS. It was a serious matter, used by business. Had a reasonable 640×400 resolution with 16 colors minimum.

          On top of that, it was compatible with its 8-Bit predecessor, the NEC PC-88. The company’s own NEC V20/V30 processors had 8080 emulation mode built-in. Some of the later PC-98 machines had both an 80386 and a NEC CPU built-in, I vaguely remember.

          And then there were all those NSFW/Hentai games for PC-98.. πŸ˜…Same story of success as with VHS, I think.

          In comparison to these things, MSX2, MSX2+ and Turbo R did quite well. Better than FM-7, PC-6001, Sharp MZ series etc, at least. And it has a community that still is alive. πŸ™‚πŸ‘

    1. I was thinking a Pico W.
      Once a stream connection can be established it’s just down to the protocol. Not sure if the specifications are complete on that though.

      Run a web server on another system, use the Pico to translate requests from the NABU and make REST calls to fetch and list programs. Could use it to add storage of its own too.

      I was interested, but the cost is likely ridiculous to acquire one for me. I just recently acquired a couple of Z80 cpus for a project though. I should get that moving instead anyway.

    2. I’m not exactly sure either, but if you go in that direction, you may as well put an CP/M emulator on it and then run it a lot quicker then the original hardware.

      There is however some kind of very vague border of what those people in the retro computing niche find fun, and what they reject. I don’t really understand the whole retro computing community but still wish them lots of fun with their hobby.

  3. I see someone already managed to print HELLO WORLD on it.

    However, I failed to see the significance of this project. There are maybe a few hundreds of them out there. The ones that are actively usable are far less. What is the point of hacking these when 8-bit machines from the 80s, like C64, are still widely available?

  4. NABU appears to be a smart terminal, what is today called a thin client, still marketed by the likes of Lenovo and Hewlett-Packard, but which eschews the coaxial cable for gigabyte ethernet.

    1. It was apparently very primitive, though.
      Even by 1980s standards. At least to me.

      Please have a look at the MUPID terminal from the 1981/1983.

      It was an intelligent BTX terminal made by our neighbors from Austria.

      MUPID II :
      Z80A @3MHz, 64KB RAM/64 KB VRAM/ 16KB ROM, RGB in/out (SCART), tape/joystick/modem/serial port, 480×250 pels maximum, 16 fixed colors+16 freely definable colors out of 4096 (CEPT specification).

      It could run Z80 code embedded in CEPT pages and even run CP/M.

      And store pages and programs (telesoftware) locally in battery-packed RAM (128KB permanent memory), if I’m not mistaken (our German C2D2 models).

      There were even two versions of CP/M available for it, even.
      One ran in the floppy drive, on the MUPID directly.

    2. In the 90s, we had something called “Channel Videodat” here in Germany.
      It was based on a technology from 1986.

      It was some sort of SatellaView, but for PCs.

      A Videodat decoder box attached to both a PC and a satellite receiver or cable tuner was used.
      It was an one-way road, just like that of NABU.

      But it allows receiving dozen of MBs of information for free.
      It was an interesting alternative to buying shareware CD-ROMs of the day.

  5. More information about the NABU can be found here:

    I’ve discovered this page by accident.
    It’s well made, IMHO, despite being under construction still.

    It also has manual scan and NABU ads.
    Very interesting little machine, yet unfinished (no 9938 or 9858 VDP, no MONITOR in ROM as with Sharp MZ series).

    There’s even a screen shot of Q*bert running on NABU! πŸ˜ƒ

    Unfortunately, it’s not nearly as cute as MSX1 Q*bert.

  6. This guy has his NABU booting and loading software just like it did in the 1980’s. A guy who worked on the system in the 80’s sent him what looks like the entire NABU software library.

    They had plans to have the NABU service for Commodore 64, MSX, and PC. One commenter said he worked at NABU and had the interfaces for all three on his desk, complete and functional, when he left the company.

  7. Turns out NABU terminal was designed by Benny Lau, one of ATI co-founders :o :)

    “I went to a company called anti-com
    which at that time they were acquired by
    a bigger company called Nabu
    which they developed
    they were ahead of their time they were
    actually developed developing a terminal
    and that is a computer that hooked up to
    a the cable through a cable modem
    so the idea was that there wasn’t any
    internet at the time
    so they were they have this idea of oh
    how about
    like that the head end of the
    cable company they store all the
    news and stocks quotes and
    games that people if you buy this
    terminal hook up to your cable
    and you can download this game news and
    whatever and then you can then play with it
    and use it so _I developed that terminal for them_
    and like they are they basically
    almost like the shell company they
    acquire a lot like say
    they acquired a company in ottawa that
    specializes in making cable modem
    and anti-com specialize in designing computers
    so they acquire all this company with
    expertise in different pieces
    and they put them into together
    to provide to provide such a service
    but the problem with the company at that
    time was they they spend money
    as quickly as they they
    raise the money the company the little
    company has about 40
    something vice presidents
    i don’t know why when they go to a
    convention in toronto they send
    40 vps
    so they’re burning money like crazy so
    so uh at that time
    my my like my manager and some of the
    at anticon they decided to quit”

    no longer NABU went bankrupt, 40 VPs :)

  8. Don’t really see the point of these. There were a buttload of Z80/TMS9918A computers made back in the day. Even if the community perfects getting data into it you’re still going to have an MSX1 style computer in a nice case.

    1. There is already an internet adapter software since some time…. you just connect it on your computer to an RS422 adapter and away you go…. it can load library of software that originally ran as well as some new stuff.

      Is it still pointless yeah. Is it retro yeah… that’s all that matters. And it is a hack.

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