Search found 39 matches

by Charles MacDonald
Sat Aug 23, 2008 11:33 pm
Forum: PC-Engine
Topic: HuC6280A Pin Assignment
Replies: 5
Views: 1691

Re: HuC6280A Pin Assignment

Here's all the custom chip pinouts. I'm cutting and pasting from my notes so excuse any spelling errors or obvious mistakes. :D HuC6280: ---------------------------------------------------------------------------- HuC6280 pin assignments --------------------------------------------------------------...
by Charles MacDonald
Tue Aug 19, 2008 9:25 pm
Forum: PC-Engine
Topic: Fun with BSY
Replies: 2
Views: 1246

Re: Fun with BSY

This is actually very interesting :-) I'm going to setup a PCE test bench and post my results. Thanks for sharing your findings! -Ki FWIW, I can't get point #3 to work reliably. Sometimes it delays for a scanline, sometimes it doesn't. The only thing that works consistently is the need to poll BSY ...
by Charles MacDonald
Tue Aug 19, 2008 9:23 pm
Forum: PC-Engine
Topic: VRAM -> VRAM DMA
Replies: 2
Views: 1353

Re: VRAM -> VRAM DMA

I can only answer #2: YES! ;D The DMA is greatly sped up when you go into 7.16 MHz or 10.73 MHz mode. I wrote a program that simulated vertical column scrolling using VRAM to VRAM DMA, and the number of scanlines used during the transfer went from 20 or so with $0400=$04 to about 3 with $0400=$06. A...
by Charles MacDonald
Wed Aug 13, 2008 3:57 am
Forum: PC-Engine
Topic: Fun with BSY
Replies: 2
Views: 1246

Fun with BSY

So at some point you probably have asked yourself what the BSY flag is for in the status register. The CPU already gets halted by the VDC when waiting for a chance to access VRAM, so having a busy flag seems redundant. I think this is how it works. When the VDC writes data to $0003, the entire word ...
by Charles MacDonald
Sat Jun 28, 2008 2:02 am
Forum: PC-Engine
Topic: VDC registers
Replies: 7
Views: 2236

Re: VDC registers

I have been running some tests, this is what is known so far: 1. Reading from $0002 or $0003 when register $04 is selected enters 'weird mode' where the VDC output going to the VCE is corrupt somehow. Garbage is displayed instead of proper background/sprite graphics data. 2. While in this mode, read...
by Charles MacDonald
Fri Jun 27, 2008 1:38 pm
Forum: PC-Engine
Topic: VDC registers
Replies: 7
Views: 2236

Re: VDC registers

Do you know if this chip was used in other devices? Maybe these registers were used on them. If only the datasheet or the hu7 docs were somewhere on the net :) It was used by Data East for the arcade version of Bloody Wolf, without a VCE. What they did was to connect VD0-VD8 to a SRAM which contain...
by Charles MacDonald
Fri Jun 27, 2008 3:37 am
Forum: PC-Engine
Topic: VDC registers
Replies: 7
Views: 2236

Re: VDC registers

There're no hints in the patent docs? I'm not even sure if this kind of information may have been available in the nec devkit. I checked and both the US and Japanese patents for the VDC make a point of skipping these registers in their descriptions, oddly enough. It may have not been officially doc...
by Charles MacDonald
Wed Jun 25, 2008 6:59 pm
Forum: PC-Engine
Topic: VDC registers
Replies: 7
Views: 2236

VDC registers

Going by equates in an include file, we have: VDC register $03 = "CTAR" VDC register $04 = "CTR" Now I'll just make stuff up: Maybe these are "color table address register" (address port, like MAWR) and "color table register" (data port, like VWR) for accessing color RAM in the VDC. While the VDC ha...
by Charles MacDonald
Sun Jun 22, 2008 5:19 pm
Forum: General
Topic: Aloha!
Replies: 5
Views: 4650

Re: Aloha!

Hello Mooz!

The forum looks very nice. Good job! :D