NEO-E0: Difference between revisions

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[[File:aes_e0.jpg|right|thumb|NEO-E0 chip found on a AES board.]]
[[File:aes_e0.jpg|right|thumb|NEO-E0 chip found on a AES board.]]


Also found on MVS boards, even those without memory card slots.
MVS specific chip.


==BIOS vector table swapping==
==BIOS vector table swapping==
When 68k A8~A23 = 0 and the [[BIOSes|BIOS]]'s vector table is chosen (by using {{Reg|REG_SWPBIOS}} or {{Reg|REG_SWPROM}}), A22I~A23I outputs are set to 1.  This makes the address appear to address decoding chips as a BIOS access instead of a [[P ROM]] access.
When 68k A8~A23 = 0 and the [[BIOSes|BIOS]]'s vector table is chosen (by using {{Reg|REG_SWPBIOS}} or {{Reg|REG_SWPROM}}), A22I~A23I outputs are set to 1.  This makes the address appear to address decoding chips as a BIOS access instead of a [[P ROM]] access.


==Memory card address latch==
On the AES, the AND gate is used for /SROMOE from /SROMOEL AND /SROMOEU.
On AES systems, BNK0~BNK2 are tied low. This makes the chip act just like a buffer ?
What are BNK0~BNK2 used for ?
 
 
The chip also ANDs the pair of 8bit output enable signals from the [[NEO-C1]] since there is only a single 16bit ROM used for the BIOS.


==MV2B @ G2 pinout==
==MV2B @ G2 pinout==

Revision as of 04:56, 14 August 2012

NEO-E0 chip found on a AES board.

MVS specific chip.

BIOS vector table swapping

When 68k A8~A23 = 0 and the BIOS's vector table is chosen (by using REG_SWPBIOS or REG_SWPROM), A22I~A23I outputs are set to 1. This makes the address appear to address decoding chips as a BIOS access instead of a P ROM access.

On the AES, the AND gate is used for /SROMOE from /SROMOEL AND /SROMOEU.

MV2B @ G2 pinout

OpenOffice Draw file: File:Neo-e0 mv2b G2.odg

  • A1~A23: 68k address bus
  • MCA0~MCA23: memory card address bus
  • BNK0~BNK2: memory card banking from NEO-D0
  • VEC: BIOS vector table swapping enable

MV2B @ F7 pinout

OpenOffice Draw file: File:Neo-e0 mv2b F7.odg

Acts just as a buffer.

  • s*: signals to both slots

Pinout

OpenOffice Draw file: File:Neo-e0.odg

  • A1~A23: 68k address bus
  • Y0~Y23: memory card address bus
  • BNK0~BNK2: comes from NEO-D0, memory card banking
  • VEC: BIOS vector table swapping enable
  • ANI0, ANI1, AND0: AND gate used to generate ROMOE from ROMOEU and ROMOEL
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