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TMS9918A Retro Video Chip Reimplemented In FPGA, With VGA Out
acadiel writes "Matthew H from the AtariAge.com TI-99/4A forum has finalized a design of a TMS 9918A replacement (with VGA out) for classic computer systems such as the ColecoVision, TI-99/4A, SpectraVision, MSX1, SpectraVision 128, and Tomy Tutor Home computers. This hardware project replaces the native video controller on these classic systems and enables them to have VGA output for the first time." (It's just under $100 to order one.)
there's actually quite a community for these old systems, and a lot of people who don't enjoy playing on emulators, or who want to recapture the original experience.
it's pretty cool that they've managed to do this, though I might prefer a different connection type... my current TV does have a VGA input, but I doubt my next one will.
Of all the chips that one on the Commodore 128/128D is a pain to convert to anything modern as it uses the old CGA/RGBI interface. All the CGA adapters ive found dont handle the intensity signal, they are more RGBA compatible.
"Enjoy what you're doing! If it becomes drudgery, you're doing it wrong!" - Jim Butterfield
he'd better do an HDMI version quick as VGA seems to be on the way out as a connector :-P
Except HDMI is a closed standard and buying HDMI chips requires signing over your first-born to Satan.
It not excessive. It's about supporting widely available monitors.
Except that you're still upconverting a signal from 240p to 480p. By going directly to VGA you're at least getting a crisp 480p image (ie: 640x480). And no, doing this after the signal has been produced at the composite outputs is not going to be as pretty.
Except HDMI is a closed standard and buying HDMI chips requires signing over your first-born to Satan.
As someone who used to worship Satan as a kid (yeah, stupid), I resent that remark. Please do not insult Satan by comparing him to a vile media consortium.
The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
And no, doing this after the signal has been produced at the composite outputs is not going to be as pretty.
Unless you're using a program that relies on the artifacts in a particular video chip's composite output. The NES PPU's architecture was heavily inspired by the TMS9918, and I know a lot of NES games rely on interactions between luma and chroma to give the backgrounds more texture.
Better, perhaps, to ask "for whom?"
Please consider that just thirty-odd years ago, one could own a computer that wasn't the university's or corporation's. Whether one came fresh to it or from mainframe milieu, there was an immediacy, a power, a whole new realm of discovery. One no longer had to submit their deck of cards to an acolyte to the high priests of a Burroughs or CDC Behemoth only to get back a core dump due to an errant comma. Some, even now, for reasons of nostalgia or fun, continue their interest and enthusiasm - vibrant 8-bit micro communities are but a search away.
The TI-99/4A offered, amongst other things, 16 sprites with built-in collision detection. At the time this was nigh magical. Sprites were effectively independent of screen - they were a 'floating' layer above it and allowed for some interesting game and simulation possibilities. SCREEN itself was a defined device; one could PEEK and POKE 'most anywhere, and PUT and GET to any device. An entire screen could be represented with a string in memory, its contents readily changed on the fly. One could read data for a string from a DATA statement in program code or from (eventually) floppy; with several strings screen-swapping, almost animation, could be done. Graphics could accompany text adventures. Add sprites? Oh, my. And now with VGA?
You may have to ask "what for?" - others will not.
You're completely, absolutely, out of you mind deluded. Sorry. At work I use some test instruments, made by Tektronix and HP, where the date codes on chips are all in the 70s. They work beautifully, and I regularly "hack" on them. They are anywhere between 30 to 40 years old at this point. There's nothing fussy and temperamental about those systems, and some of them are so complex that a consumer-grade microcomputer or game console holds no candle to them. I'd say that all of the consumer systems that this chip replacement would go into are comparably simple. If you would really have a problem with them, then it's your problem, not a general one. If you want complex, take any modern PC and try replacing a BGA chip in it. I'd take a 30 year old piece of gear any day, I probably could do chip swaps in those blindfolded.
A successful API design takes a mixture of software design and pedagogy.
Actually, it was 32 sprites, with a limit of 4 to a line. It had collision detection but it was rarely useful. It had a single bit to tell you that any sprite hit any other sprite. To figure out what hit what, you'd have to walk the descriptor list and do the actual computation yourself. (Or, in the case of TI Extended BASIC, the interpreter had to do it for you.)
On the TI-99/4A, that meant actually accessing VDP memory, since there wasn't much other RAM in the system. That itself was pretty slow, because it wasn't memory mapped for the CPU. You have to write to the VDP's address register, and then do repeated reads after it fetched the byte. Depending on the display mode, that could be as long as 8us during active display (Graphics II mode -- everybody's favorite "bitmap" mode.). Fortunately, the address pointer auto-incremented, so if you were accessing a contiguous structure like the sprite descriptor list, at least you didn't have to keep reloading the address.
Not that TI Extended BASIC was necessarily able to do that, of course. (Read up on the abomination that was GPL. Not the license, but the interpreted language that much TI software was written in, including TI BASIC.) But if you wrote your own assembly code, you could make that optimization, which is probably how Parsec was able to do its soft-scrolling in the time allotted.
(Actually, VDP RAM isn't memory mapped on any platform that I know of. But other systems have CPU-addressable memory that you could store a shadow copy of data in at least. The paltry 256 bytes on the TI-99/4A, though, are far from enough in many cases.)
Program Intellivision!
I'm sorry you apparently fail at reading comprehension so allow me to break it down. What you have was NOT consumer crap, what you have was designed for business and engineering which had waaaaay better quality parts. the caps and chips used in CONSUMER grade crap was then as now simply not up to the quality of professional instruments which is why we have workstations and desktops with the desktops having significantly lower quality caps, PSUs,fans etc.
We're talking about stuff built for kids in the early 80s and you are talking about HP back when they were THE scientific brand, I'm sorry pal but you couldn't be any more off base if you actually tried and those that marked you interesting obviously don't know how big a quality difference there was between HP and brands like Coleco whose other claim to fame was fricking cabbage patch dolls.
ACs don't waste your time replying, your posts are never seen by me.