ajenner

10 ms·

31.
by ajenner 8y ago
I'm another person who regularly uses PSP (version 4 in my case) for most of my day to day bitmap editing tasks - it's fast, stable and has most of the features I need so I've never felt the need to upgrade!
32.
by ajenner 8y ago
Yes - I took a remote job partially so that I could live whereever I wanted. I've been living in remote South-West England (Cornwall) for 6 years now and I love it here! It does limit opportunities in some ways but it's beautiful
33.
by ajenner 8y ago
It's too bad there is no transistor-level model of the 8088 yet (at least a publicly available one). There have been some detailed die shots of the 8088 but only of the top layer, which misses out about half of the data in the microcod
34.
by ajenner 8y ago
My current emulator is quite a lot slower than other 8088 emulators, but still quicker than real-time - it gets about 12.9MHz on a 2.67GHz Core i7 920. There are probably quite a few more things that could be done to optimize it. My "c
35.
by ajenner 8y ago
I'm one of the creators of this demo. For the past several months I've been working on a cycle-exact 8088 emulator (that will eventually be able to run 8088 MPH properly). I don't have it hooked up to any audio or video outpu
36.
by ajenner 9y ago
According to http://www.faqs.org/faqs/fonts-faq/part2/ bitmap fonts are not copyrightable in the US, where the site is hosted.
37.
by ajenner 9y ago
The accesses causing issues here are not guaranteed to use SS - that only happens for effective addresses [ebp+...] and [esp+...]. If ESP is copied into another register first (which in practice will almost always be the case) then the acce
38.
Mentor Graphics releases GCC for 8088, 8086 CPUs(blogs.mentor.com)
3 points by ajenner 10y ago|0 comments
39.
by ajenner 10y ago
It doesn't, because there are lots of special-purpose x86 instructions that would be more trouble than they're worth to teach a compiler about. For example, instructions for accessing particular CPU features that the C and C++ lan
40.
by ajenner 10y ago
> you would never use U"hello!" in pre C11/C++11. I have seen real world code which does almost exactly that and which broke (fortunately with a compiler error rather than silently changed code) when compiled with a C++11
41.
by ajenner 11y ago
The video is a bit misleading here - most CGA composite games didn't use the 2bpp mode at all but instead used the 1bpp mode. This gave 15 reasonably nice colours distributed roughly evenly through RGB space, and was also more consiste
42.
by ajenner 11y ago
The Kefrens bars effect is the part of 8088 MPH that is most sensitive to the instructions being a cycle faster or slower here or there. The MCL86 doesn't claim to have perfect emulation of timing, so I would not necessarily expect thi
43.
by ajenner 11y ago
They did, and it worked! The RCA connectors on the IBM EGA card aren't connected to anything - they only work if an add-on daughterboard is installed (I don't know if that daughterboard was ever actually made).
44.
by ajenner 11y ago
Yes, if 8088 MPH was sent back in time to 1981 it would have been possible to run it on even the very first PCs. You'd need a pretty expensive RAM upgrade (640kB was a lot then - the first PCs had up to 64kB on the motherboard) a doubl
45.
by ajenner 11y ago
This is true for proper standards-compliant NTSC signals, but a comb filter won't help you for CGA since the CGA card generates an integer number of color carrier cycles per scanline (228, not 227.5). So the phase isn't reversed e
46.
by ajenner 11y ago
Cool hack! As with other non-composite CRTs, the 5154 doesn't actually have a pixel clock so you don't need to output pixels at exactly 14.318181MHz - the timings of the horizontal and vertical sync signals are the critical thing.
47.
by ajenner 11y ago
It's surprisingly straightforward - take your input composite signal C and multiply it by a sin wave and a cosine wave (both of frequency 3.58MHz). Then take the three resulting waveforms (C, C sin(f) and C cos(f)) and filter them to r
48.
by ajenner 11y ago
Not exactly... The Nyquist frequency is half of the sampling rate of a digital signal. There isn't really any sampling going on here. The CGA does generate a signal with a pixel rate of 14.318MHz, so the Nyquist frequency of that is 7.
49.
CGA in 1024 Colors – A New Mode: The Illustrated Guide(8088mph.blogspot.com)
93 points by ajenner 11y ago|11 comments
50.
by ajenner 11y ago
There's now a (less technical but prettier and easier to understand) writeup at http://8088mph.blogspot.co.uk/2015/04/cga-in-1024-colors-new... .
51.
by ajenner 12y ago
I wanted to make some pictures to go with the article, but I didn't have time (I wanted to get the article out quickly as there was so much curiosity and speculation about the methods we used). I just tried adding a quick hack to cga2n
52.
by ajenner 12y ago
Here you go: http://www.reenigne.org/misc/cga_1k_colours.png
53.
by ajenner 12y ago
I just tracked down MODEdit at http://www.pouet.net/prod.php?which=50179 . The documentation claims it needs a 10MHz CPU. I tried it on DOSBox and it was able to play through the PC Speaker, but when slowed down to 4.77MHz-
54.
by ajenner 12y ago
The 3D part used a more conventional 16-colour mode. Though it's a testament to how well Scali's code and VileR's palettes work, if they can be mistaken for the 1K colour mode!
55.
by ajenner 12y ago
The CPU usage isn't that bad compared to some of the other things we did in the demo - with some help from interrupts it could be done with maybe 20% of CPU. There is also a much easier ~500 colour variant which doesn't take any
56.
by ajenner 12y ago
It runs on top of DOS, using INT 0x21 to spawn the effect executables. The loader doesn't read the executables directly, it just decides when to start and stop them, plays music and bounces some text up and down while the effects are l
57.
by ajenner 12y ago
The first part of my technical writeup is now at http://www.reenigne.org/blog/1k-colours-on-cga-how-its-done/
58.
by ajenner 12y ago
Totally deterministic. I think there's even an emulator which models it (though without a cycle-exact emulation of the CPU the snow won't be in the same places as on real hardware).
59.
by ajenner 12y ago
I wanted to do some more impressive animation with the 1K color mode, but ran out of time unfortunately. One tricky part about doing animation with this mode is that it suffers from the "CGA snow" bug (visual glitching when writin
60.
by ajenner 12y ago
I can't speak for the other authors, but I for one plan to release the source code for the parts I wrote (it needs a bit of cleaning up first, though, and I want to get the technical write-ups done first).

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