Wanted: V9990 chip for hardware development

By FarmerPotato

Supporter (5)

FarmerPotato's picture

04-01-2020, 17:47

I want to buy a single V9990 chip for development. I am building my own computer with a V9958 already, and want to add V9990 superimposed.

From China I have a quote for MOQ 50 pcs @ $24 each. Realistically, I only need 1-2 pcs for development. I also don't know if this source has genuine V9990.

Does anyone have a supply? Can you sell me one or two?

Again, just the chip! I don't need a GFX 9000 cart (since removing the chip might damage it).

I would love any help in finding a supplier.


Here is a concept design of the computer:

Geneve2020 pics

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By sdsnatcher73

Prophet (2340)

sdsnatcher73's picture

05-01-2020, 05:27

I don’t have a V9990 for you. But those pictures show a lot of I/O (suggesting a Pi is used) and you mentioned real VDP. So that makes me wonder what you are building here, meaning please tell us something more Wink

By jltursan

Prophet (2561)

jltursan's picture

05-01-2020, 12:34

Hi and welcome FarmerPotato, I've seen your developments in AtariAge Wink

Let me guess, is it a Geneve 9640 evolution?, if so, it's uber-cool!. Any specs?.

By FarmerPotato

Supporter (5)

FarmerPotato's picture

05-01-2020, 18:23

Hi sdsnatcher73 and jltursan,

Yes, it's a follow-on to Geneve 9640. A tough goal is to be 100% software compatible (or 95% plus workarounds, or whatever it takes.)

My design goal is to use real chips wherever I can. I'm using one Lattice ICE40HX8K FPGA for all the compatibility magic, but two real CPUs, a V9958 and so on. I'm not interested in MAME-in-a-box. There is a "Pi" connector but it refers to attaching a "TiPi" bridge to use an external Pi3 for telnet, http, and file server. This is an established peripheral for the TI-99/4A.

I've been working on prototype PCB layout over the holidays. When I post that update it will be more clear how all the I/O is handled.

I would appreciate input from the MSX community, especially about using the FM chips (most likely using OPNA, or OPL3.)

If I can get a V9990 solution, that will be added as extra video modes in addition to the V9958 (needed for compatibility!)

Here are the specs so far:


I've been working on a design that I call Geneve 2020. This is a standalone TMS99105 computer with the ability to host MDOS and run Geneve software, but it is all original TI and Yamaha chips, to the fullest extent possible. It is not emulation! There will be a modern "gate array" FPGA that provides the memory architecture of the Geneve 9640 on top of the TMS99105 computer.

== Hardware

TMS99105 at 6MHz, full 16-bit operation, up to 6x performance of the
TMS9995 in Geneve 9640.

V9958 (MSX-Video) for original Geneve graphics, same analog RGB 15kHz plus VGA sync
(use new Acer G276 or an old monitor)

F18A socket for optional VDP, switchable or 2 monitors at once

up to 32MB of no-wait state RAM in 2 user-swappable SIMM 30-pin slots. Supports 2MB, 8MB, or 32MB.

2 SD card slots for main storage

TMS9901 for real 4A keyboard and joysticks

TMS9995 I/O coprocessor for PS/2 keyboard/mouse, Hexbus, serial.

TMS9902 x4 for two standard RS232 ports, one high-speed 115200 bps, one
31500 bps MIDI IN/OUT.

YM2608B x2 for 12-voice synthesizer:
Yamaha's OPNA 4-op FM synthesis as heard in Sega Genesis (YM2612)
Other audio capabilities in the YM2608B are 8kHz PCMCIA player, drums, AY-8910-3 (Intellivision)
Possibly YMF-262 x2 (OPL-3) (Sound Blaster) or YMF-278 (Moonsound)

TSM5220C for speech (slight incompatibility.. or get your original chip out of your TI Speech Synthesizer.)

SN76489 x4 - not actual chips, but no-wait state soft cores in FPGA, for 12 voices

All audio streams mixed digitally in FPGA. CS4344 for digital-to-analog stereo out.

Actual cartridge slot for running 4A carts

256K EPROM, 256K Static RAM

== Connectors

PS/2 keyboard and mouse

VGA(RGB 9958), or DP (F18Amk2)

5V regulated power (or maybe 7.5V unregulated)

Two SD card slots (one for boot, one for user)

RS232, PIO

TIPI connector for Internet (external Pi3, not used for any onboard functions)


Stereo phono out, RCA left/right jacks


Switchable TI or Atari joysticks

Cartridge Slot

== Software

Supervisor OS kernel, in EEPROM, patches MDOS for compatibility as needed

MDOS as a user application: 2MB memory space

GPL under MDOS

SAMS support under GPL

== What's FPGA synthesized, not real chips

74LS610 Memory Mapper
General memory map emulation, 16-to-8-bit bus routing
DRAM refresh controller
I2C and SPI interfaces to peripherals
SN76489 (x4)
Digital sound mixing and SPI interface to CS4344 audio DAC
TMS6100 Speech vocabulary ROM
TMS9901 for legacy keyboard/joysticks/timer (but real 9901 also used)

== Final

I'm acutely aware that there have been several vaporware Geneve projects. I update the status thread regularly with design documents and progress reports, especially pretty pictures, to let you know that it's alive.

Geneve 2020 Discussion Thread in TI-99/4A Development


Geneve owner from 1988
TI-99/4A owner from 1982