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#121621 11/28/22 02:26 PM
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I watched Adrian's Digital Basement video on the Nabu Network Computer. It's a z80 paired with a tms9918 that hooked up to a cable system and would download software from the cable. It had its OS downloaded to it that was based on CP/M.

It failed commercially, but it's getting new life thanks to a lot of NOS systems currently being sold.

York University has a recreation of the network, they call YUNN.

http://www.cse.yorku.ca/museum/research/NABU.htm
https://museum.eecs.yorku.ca/nabu


There's new efforts to software downloaded to it via it's RS-422 network interface.


It's interesting to find stories about nabu:

https://www.mslinn.com/resume/history/nabu/
https://ottawarewind.com/2018/12/02...s-coke-fueled-1980s-video-game-industry/

Just wondered if anyone else is fascinated by the Nabu?

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Yes; Luigi Thirty has been working on emulating it, and has even been posting WIP screenshots over on Discord.

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Thanks for the pointer, JD.

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I checked out Luigi30's repo and unfortunately I don't have the keyboard rom, but if I change it to NO_DUMP it will run without it:

ROM_LOAD("keyboard_rev_a.bin", 0x0000, 0x0800, NO_DUMP)

[Linked Image from i.imgur.com]

Awesome!

(The font is interesting, the K and R seem wacky, maybe it looks better on a television)

Last edited by Golden Child; 11/30/22 09:46 AM.
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Mesa no carrrrrrin' about the Naboo. The Naboo think they are so smarty. They think their brains so big.

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Vas Crabb #121635 11/30/22 12:01 PM
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Originally Posted by Vas Crabb
Mesa no carrrrrrin' about the Naboo. The Naboo think they are so smarty. They think their brains so big.

Wesa give yousa una Bongo.

Now... gooooo.

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Some silly fun, the nabu uses the same vdp and sound chip as msx1. So why not try to patch the msx bios rom to use nabu addresses?

The msx has the vdp on addresses 98 and 99, where the nabu has it on a0 and a1.

The msx has the AY-3-8910 on addresses a0/a1/a2 while the nabu has it on 40/41.

msx a0 is reg write nabu is 41 reg write
msx a1 is write data nabu is 40 write data
msx a2 is read data nabu is 40 read data

So if I take the bios from a canonv20e, and do a little search and replace with a hex editor:

change the sound io addresses:

d3 a0 -> d3 41 out ($41),a
d3 a1 -> d3 40 out($40),a
db a2 -> db 40 in a,($40)

change the vdp io addresses:

d3 98 -> d3 a0
db 98 -> db a0
d3 99 -> d3 a1
db 99 -> db a1

then substituting the modified msx bios for the nabu's rom, then starting up directly into the debugger and then performing a "load starblaz.rom,4000", "pc=w@4002", and then running it, it doesn't quite work. The starblazer code looks to address $0007 for the address of the vdp, loading that into the c register and then doing an out (c),a. If we patch that in the rom to address 0xa0, then star blazer will run:

Code
5967: 3A 07 00    ld   a,($0007)
596A: 4F          ld   c,a
596B: 21 30 E4    ld   hl,$E430
596E: 06 80       ld   b,$80
5970: 7E          ld   a,(hl)
5971: ED 79       out  (c),a

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

Unfortunately, it isn't playable because the roms access the hardware to read the joystick (msx reads the joystick from the sound chip register 14). It should be possible to patch the roms and bios to read and translate the keyboard and joystick.

But the sound and video seems to work ok.

Note that this only seems to work with 16k roms like mappy, galaxian, starblaz and pacman, and if there isn't a bunch of direct hardware access in the rom.

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So if you take the pictures of the Nabu keyboard that are on deskthority, and follow the traces, you'll find that they pretty much match the table in the rom.


[Linked Image from i.imgur.com]

Table at FC76 is the unshifted keycodes.

Key matrix Rows and Columns match the rows and columns in the table.

So the first row consists of ESC (1B), Right Arrow -> (E0), P, W, R, I, ]

You can trace the line that goes from ESC to W to R to I to P to ] and to Right Arrow (RGT E0).

[Linked Image from i.imgur.com]

Table at FCFE is the shifted keycodes.

[Linked Image from i.imgur.com]


I think I understand how the matrix is scanned. P1 data direction is set to 7F, so the low 7 bits control the scan. Lowest 3 bits are the column address and the next 3 bits are the row address. I think these must feed into 3 to 8 decoders to go to the matrix.

So basically, it counts from 0 to 42, and looks at the MSB being set on P1 to determine if the key is pressed or not.


[Linked Image from i.imgur.com]

STA $02 writes to Port 1.
LDA $02 reads from Port 1.


Special lines are #$40, #$41, #$42, must be for CTRL and SHIFT.

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I think someone's working on a driver for this, there's no need to deep dive it :-)

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Brijohn's stuff looks amazing:

I saw this today and am just dying to try it:




Got it working, I must say this is awesome...(thank you BriJohn and DJ Sures)

(the menu selection with the keyboard was a little wonky, but that's because the arrow keys are also mapped by default to the joystick so mapping the joystick to the numeric keypad avoids "double" moves where you're moving with the keyboard arrow and the joystick simultaneously.)

Last edited by Golden Child; 12/13/22 09:01 PM.
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