Re: 16 bit data bus on a 6502.

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Mon, 12 Oct 2020 22:44:10 +0200 Message-ID: <7f188e1c-b2d4-468a-22f3-90becdfd03ce_at_laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

On 10/12/20 10:32 PM, tokafondo wrote:
> Thanks. I'm going back to the first proposal I made to Bill Mensch.
> 
> So, would...
> 
> CLC
> XCE
> REP #$20
> LDA #$ABCD
> STA $1000
> SEP #$20
> LDA $1001
> STA $ADDRESS_OF_PARALLEL_PORT_CONNECTED_TO_MSB_OF_16BIT_MEMORY_CHIP
> LDA $1000
> STA $ADDRESS_OF_16_BIT_MEMORY_CHIP_BEING_LSB_OF_PARALLEL_PORT_VALUE
> 
> ...work?

You don't do it this way when talking to a 8Bit I/O-chip. 16Bit-CPUs 
have commands that only output 8 Bits. If the I/O-Chip is 16 Bit wide, 
then all 16 Bit will be transfered at the same time with 16 Bit I/O command.

  Gerrit