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27 March 2010
Posted in
Document Library -
Atari Memos and Documents
Video Disk Hardware Specification
_________________________________
(For Playland, Road Runner, Temple of Doom, Firefox?)
VIDEO BOARD
___________
> Playland Sync Chain
> Motion Objects *
> Alphanumerics *
> Scrolling Playfield (without averaging)
> Priority RAM *
> Color RAM *
* more detail to follow
Motion Objects
- 56 (approx.) 8 X 128 pixels
- 4 bits deep
- interlaced
- 8 picture nos./M.O. (each picture no. specifies 8 X 16 object)(see note 1)
- 2 banks M.O. RAM
- H & V reflect
- 1024 8 X 16 pictures in 4-27128's (see note 2)
- disable bit - blanks all M.O.'s but preserves both RAM banks
NOTE 1: 8 X 16 objects will appear square in interlaced format
NOTE 2: actually 4 banks of 256 pictures -- all 8 pictures in a
single M.O. must come from the same bank
Alphanumerics
- 2 bits deep
- non-interlaced (double scanned lines)
- 8 X 8 pixels per stamp (square aspect ratio - approximately)
- 2 banks of 256 pictures in 1-2764
- approx. 46 X 30 stamps on screen
Scrolling Playfield
- 8 X 8 stamps
- 4 bits deep
- non-interlaced (double scanned lines)
- approx. 46 X 30 stamps on screen
- Horizontal and Vertical scroll registers
- 2048 pictures in 4-27128's
- H & V reflect on stamp by stamp basis
- no pixel averaging! (this means approx. 18 stamps horizontal scroll
buffer and 2 stamps vertical scroll buffer)
Priority RAM (PROM?)
- 1K X 4
INPUTS - 4 bits motion object video
- 4 bits scrolling playfield video
- 2 bits alphanumerics
OUTPUTS - 2 bits priority
- 2 bits pallet (or palette) select
- I will make it a PROM unless someone objects (profusely)
-2-
Color RAM
- 1024 X 16
- 4 banks of 256 X 16 (banks are optional)
- 4 priorities
- 4 pallets per priority (16 registers per pallet)
- Outputs (proposed)
- 4 bits RED
- 4 bits GREEN
- 3 bits BLUE
- 3 bits INTENSITY
- 2 bits MIXING
CPU BOARD
__________
> 6502 or 6809 (master) -- selectively stuffed (one OR the other)
> 6502 Sound processor (slave) *
> parallel disk interface (master)
> serial disk interface (slave)
> RAM *
> ROM *
6502 Sound Processor
- NMI'd prot for communication with master
- 6532
- IRQ timer
- external IRQ from serial port
- IRQ timer
- IRQ's from 6532
- Quad Pokey
- TI speech
- stereo
RAM
- 4K bytes in one of two configurations
1) 4K fixed
2) 2K fixed
2K in 256 byte banks (128 bytes in Z-page, 128 bytes in page 2)
ROM
- 256K bytes (16-27128's)
- 44K program address space
- Configurable as
40K fixed + 4K banks
OR
12K fixed + 32K banks
- Suggestions for implementation of configurable address space:
- configuration PROM or RAM (downloaded from fixed ROM)
- seclectively stuffed address decoders
Memory Map Usage
Video Board
Motion Objects 2K
Playfield 4K
Alphanumerics 2K
Color RAM 2K
Misc. 2K
__
12K
CPU Board
RAM 4K
ROM 44K
Misc. 4K
__
52K
Total 64K
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