bbc_vidproc

Files
file	bbc_vidproc.cdl
	BBC microcomputer video ULA CDL implementation.

Detailed Description

Modules

module bbc_vidproc::bbc_vidproc	(	clock	clk_cpu,
		clock	clk_2MHz_video,
		input bit	reset_n,
		input bit	chip_select_n,
		input bit	address,
		input bit	cpu_data_in[8],
		input bit	pixel_data_in[8],
		input bit	disen,
		input bit	invert_n,
		input bit	cursor,
		input bit	saa5050_red[6],
		input bit	saa5050_green[6],
		input bit	saa5050_blue[6],
		output bit	crtc_clock_enable,
		output bit	red[8],
		output bit	green[8],
		output bit	blue[8],
		output t_bbc_pixels_per_clock	pixels_valid_per_clock
	)

Parameters

[in]	clk_cpu	2MHz bus clock
[in]	clk_2MHz_video	2MHz video
[in]	reset_n	Not present on the chip, but required for the model - power up reset
[in]	chip_select_n	Active low chip select
[in]	address	Valid with chip select
[in]	cpu_data_in	Data in (from CPU)
[in]	pixel_data_in	Data in (from SRAM)
[in]	disen	Asserted by CRTC if black output required (e.g. during sync)
[in]	invert_n	Asserted (low) if the output should be inverted (post-disen probably)
[in]	cursor	Asserted for first character of a cursor
[in]	saa5050_red	3 pixels in at 2MHz, red component, from teletext
[in]	saa5050_green	3 pixels in at 2MHz, green component, from teletext
[in]	saa5050_blue	3 pixels out at 2MHz, blue component, from teletext
[out]	crtc_clock_enable	High for 2MHz, toggles for 1MHz - the 'character clock' - used also to determine when the shift register is loaded
[out]	red	8 pixels out at 2MHz, red component
[out]	green	8 pixels out at 2MHz, green component
[out]	blue	8 pixels out at 2MHz, blue component