NABU PC – A 1984 Z-80 Computer You Can Buy Today – Hackaday
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. 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 64kB of RAM. A TMS9918 handles video, while a General Instrument AY-3-8910 does the sound. 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?
Fortunately the German version, the NADU is still available. But reserved to Germanophones.
It’s really cool, except for the video processor!
It’s the same lackluster processor as used in the MSX1 standard!
Which had a few gems, but largely a lame game library compared to the MSX2. 🙁
https://www.msx.org/wiki/Texas_Instruments_TMS9918
If it had something like a Yamaha V9938 or similar, it could be so much better.
Things like SymbOS could be ported to it, maybe.
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.
The most limiting thing on a TMS9918 is the scrolling, sadly. Have to use all sorts of tricks to make something that scrolls anywhere near decent-looking.
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.
There’s a mention in the comments about the other half that connects to the cable. It really was ahead of it’s time regardless of current feelings towards dependencies.
yes a pity that cable was practically unidirectional at the time. The WebTV would be a decade later, and the NAPLPS was also the basis of Prodigy network some years later.
I seem to remember some being download via cable, and upload via dial-up.
Bought one dirt cheap a couple of years ago, simply for the sheet-metal case, which is eminently re-usable.
Already all sold out. Apparently I missed my chance!
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.
Thanks for the update! I’ll set an eBay notification and get a couple on the next round.
71 sold. Small warehouse? $45 shipping. Bah Humbug!
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.
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.
Those are the network adapters, not the NABU computer.
“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!
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.
Thank you for the answer. This makes it a lot less exciting. Adrian’s description certainly insinuated two way transmission.
If Google shuts down will my phone still work?
If Google shuts down, they will take much more than phones down with them.
I’m sure even 007 is afraid to take on those super villians.
Here’s a video of a guy who dumped the NABU rom and converted it back to assembly, he also put it on his GitHub page.
https://www.youtube.com/watch?v=w77_ruzXJPk shows uploading code to the NABU.
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?
“This equipment provided the interface between the 117 MHz cable signals that were exchanged between the DEC server and the user’s TV.”
Nope all gone around US. Saw some without keyboards, just the other day.
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.
You’re right, I think. Though the article at msx.org says that the “A” was dropped in later revisions for some unknown reasons.
https://www.msx.org/wiki/Texas_Instruments_TMS9918
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.
The TI-99/4A is pretty capable. I wonder how much of this demo is the 16 bit CPU and how much is the TMS9918A? https://www.youtube.com/watch?v=ZhSUhE03XFw
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. 🤷♂️ 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)..
I forgot to thank you for the link of that cute demo. Thanks a lot!
Just did finish reading the comments on pouet.net, there’s even a photo of a physical cartridge! 🙂👍
MSX2 wasn’t a hit in Japan. It did sort of okay, but was completely eclipsed by the Famicom (as a game machine) and the PC98 series (as a personal computer).
I wonder how much job to get a cheap ESP32 to function as a faked cable network+modem but with the required storage to “broadcast” the programs.
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.
apparently underway by a son of one of the engineers, and soliciting for contributors
https://youtu.be/FFaWJu3hDP4?t=810
Full technical specs including memory map and programming guide for the NABU, about midway down this page:
http://dunfield.classiccmp.org/nabu/index.htm
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?
The point is because you can take something that doesn’t work and make it work.
Please be kind and respectful to help make the comments section excellent. (Comment Policy)
This site uses Akismet to reduce spam. Learn how your comment data is processed.
By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more