CPROM: Difference between revisions

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The CPROM board uses a [[74161|74HC161]] (4-bit latch) and a [[7408|74HC08]] (quad 2-input AND gate), with a [[7404|74HC04]] (hex inverter) to unify the two RAMs.
The CPROM board uses a [[74161|74HC161]] (4-bit latch) and a [[7408|74HC08]] (quad 2-input AND gate), with a [[7404|74HC04]] (hex inverter) to unify the two RAMs.


== Disch's Notes ==
  Here are Disch's original notes:
  ========================
  =  Mapper 013          =
  ========================
 
 
  aka:
  --------------------------
  CPROM
 
 
  Example Game:
  --------------------------
  Videomation
 
 
  Notes:
  --------------------------
  This mapper uses 16k of CHR-RAM.  CHR-RAM is swappable.
  It also has bus conflicts!
 
 
 
  Registers (**BUS CONFLICTS**):
  --------------------------
    $8000-FFFF:  [.... ..CC]
      C = Select 4k CHR (RAM) page @ $1000-1FFF
 
 
 
  CHR Setup:
  --------------------------
 
        $0000  $0400  $0800  $0C00  $1000  $1400  $1800  $1C00
      +-------------------------------+-------------------------------+
      |            { 0 }            |            $8000            |
      +-------------------------------+-------------------------------+
== See also ==
== See also ==
* [http://kevtris.org/mappers/nes_discrete/NES_CPROM.html Kevtris's notes]
* [http://kevtris.org/mappers/nes_discrete/NES_CPROM.html Kevtris's notes]
* The [[NROM-368]] proposal is also compatible with this board.
* The [[NROM-368]] proposal is also compatible with this board.

Revision as of 21:24, 16 April 2015

NES-CPROM (no HVC-CPROM known) is a particular Nintendo cartridge board which uses discrete logic to provide up to four 4 KB banks of CHR RAM. The iNES format assigns mapper 13 to this board. Only Videomation, a paint program for NES, is known to use it.

Overview

  • PRG ROM size: 32 KiB (DIP-28 standard pinout)
  • PRG ROM bank size: Not bankswitched
  • PRG RAM: None
  • CHR capacity: 16 KiB RAM (in two 8KiB RAMs)
  • CHR bank size: 4 KiB
  • Nametable mirroring: Vertical
  • Subject to bus conflicts: Yes

Banks

  • PPU $0000-$0FFF: 4 KiB fixed CHR RAM bank (first page)
  • PPU $1000-$1FFF: 4 KiB swappable CHR RAM page

Registers

Bank select ($8000-$FFFF)

7  bit  0
---- ----
xxxx xxCC
       ||
       ++- Select 4 KiB CHR RAM bank for PPU $1000-$1FFF

Hardware

The CPROM board uses a 74HC161 (4-bit latch) and a 74HC08 (quad 2-input AND gate), with a 74HC04 (hex inverter) to unify the two RAMs.

See also