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Showing results for tags 'TMS9918A'.
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Has anyone ever tried figuring out how old your beloved machines are going by the occasional date codes printed on the microchips used on the console CPUs and cartridge ROMs? For example, some Texas Instruments chips may have a date code in the format of year/week. One or more of these may have "8249" stamped on it, which means year 1982, week 49. I am sure there are other date code formats used on these besides. Have any of you discussed date codes of microchips yet? ~Ben
Hello fellow 99'ers... I have a bit of a proof-of-concept I'm mulling over... create a large full-screen (maybe just the upper two sections) scrolling map in full bitmap mode on the TI. I'm trying to figure out the best implementation for this. The first method I had in mind was to treat bitmap mode as it is, characters 0-31 along the top row, 32-63 on the next, etc. Moving in a given direction just rotates the screen table assignments and then loads new graphics patterns for the newly visible blocks. The problem I see with this method is you can't buffer anything. It's going to LOOK messy, with characters you just moved out of view re-appearing briefly on the other side until it fills in graphics patterns. Seems way too slow and awkward... The other method would be to have specific character assignments for given tiles (wall, floor, etc). This becomes much easier to implement, but you lose the flexibility of bitmap mode, and you artificially limit yourself to 256 patterns maximum. (My intent is to possibly have much more than that...) So the only thing I can figure on doing is a hybrid approach; treat some part of the character table set as fixed pattern, and then have any objects/tiles I want to be unique actually occupy their own character patterns. That lets me quickly build a new view in CPU memory and output it to VDP quickly. The main headache I can foresee here is that you're going to have to manage those patterns and figure out when a given pattern is available... could end up getting very annoying. Has anyone dealt with this, or has some insight I may be missing? Adam
Check out this thread from the Colecovision forum: http://atariage.com/forums/topic/216268-my-first-test-on-the-tms9918/ Maybe this can be used also on our system? Both systems share the same VDP.
Hey all, Here is a question... so the TI disk system reserves space at the top of VDP memory for file buffers. You can reduce this by from 3 file support to 1 by calling the FILES subprogram, but it still takes up space from about >3B00 onwards. My question is... can you safely wipe out this section, say if you wanted to put the sprite pattern table at >3800 onwards? Obviously it would trash the sprite pattern table if you had to do a file load later on, but if you could restore the data from CPU memory afterwards it seems alright. Obviously it would be stupid to try and do a memory image load INTO this section...