| The TI-99 was pretty much the only
computer to use the TMS9900, just like the Cpu itself, the TI-99
wasn't designed like most computers - with almost all it's ram as
VRAM - it actually uses VRAM to store basic programs (which is not
as fast as 'proper' memory!!) Specs:
|
 |
ChibiAkumas Tutorials
Lesson H1 - Hello World on the TI-99
Lesson P1 -
Bitmap graphics on the TI-99
Lesson
P2 - Joystick and Key Reading on the TI-99 with the CRU
Lesson
P3- Sound with the TMS9919 on the TI-99
Useful Documents
1602000-9701_TM990_100M_Users_Guide_Dec78 - See Page 4-01 onward
TI Memory Map
| Address | Details |
| >0000 | Console / ROM / OS / GPL Interpreter / BASIC Interpreter |
| >2000 | �Low� Ram Expansion (8k of 32k) |
| >4000 | Device Service Routines |
| >7000 | Cartridge ROM / Page Flip |
| >8000 | RAM Memory Mapped Devices - VDP,GROM, SOUND, SPEECH. |
| >8000 | CPU Memory 256 byte block |
| >8400 | Sound Chip |
| >8800 | VDP Data Read |
| >8802 | VDP Status Read |
| >8C00 | VDP DATA Write |
| >8C02 | VDP Address Write |
| >9000 | Speech Read |
| >9400 | Speech Write |
| >9800 | GROM Data Read |
| >9802 | GROM Address Read |
| >9C00 | GROM Data Write |
| >9C02 | GROM Address Write |
| >A000 | High Ram Expansion (24k of 32k) |
TI VDP Memory Map
| Address |
Details |
| >0000 | Screen Image |
| >0300 | Sprite Attrib |
| >0380 | Color Table |
| >0400 | Sprite Descriptor |
| >0780 | Sprite Motion |
| >0800 | Pattern Generator |
| >1000 | Free Space |
| >3500 | Disk DSRs |
TI Default Charset
The Character set has no lowercase characters.
TI Key Map
To select a column of the Keymap we use CRU
Address 0024h, we can then read in from the address 0006h
We can read a whole column into R4 with ST
R4,8
We can test a single bit with TB n - where n
is the bit (offset from 0006h) to test
| CRU Address | Col 0 | Col 1 | Col 2 | Col 3 | Col 4 | Col 5 | Col 6 | Col 7 |
| 0006h | = | . | , | M | N | / | J1-Fire | J2-Fire |
| 0008h | space | L | K | J | H | ; | J1-Right | J2-Right |
| 000Ah | enter | O | I | U | Y | P | J1-Left | J2-Left |
| 000Ch | 9 | 8 | 7 | 6 | 0 | J1-Down | J2-Down | |
| 000Eh | fctn | 2 | 3 | 4 | 5 | 1 | J1-Up | J2-Up |
| 0010h | shift | S | D | F | G | A | ||
| 0012h | ctrl | W | E | R | T | Q | ||
| 0014h | X | C | V | B | Z |
Sound on the TI99
The TMS9919 uses memory mapped port 8400h for its sound control... This port takes a single byte of data - except for tones which take 2 bytesThe data we send is in the format below:
| Bits | |||||||||
| Command | Bit Details | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Format Template | L=Latch C=Channel T=Type XXXX=Data | L | C | C | T | D | D | D | D |
| Tone - Command 1/2 | C=Channel L=tone Low data | 1 | C | C | 0 | L | L | L | L |
| Tone - Command 2/2 | H= High tone data (Higher numbers = lower tone) | 0 | - | H | H | H | H | H | H |
| Volume | C=Channel (0-2) V=Volume (15=silent 0=max) | 1 | C | C | 1 | V | V | V | V |
| Noise Channel | (Channel 3) M=Noise mode (1=white) R=Rate (3=use tone 2) | 1 | 1 | 1 | 0 | - | M | R | R |
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| Please note: I wlll upload more content to these alt platforms based on the views they bring in |
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Learn 68000 Assembly  |
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Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!
Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!
Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!