+jedimatt42 Posted February 17, 2019 Share Posted February 17, 2019 Ok, so I understand the SID Master 99 is mapped into the 0x4000 - 0x5FFF space when no other DSR roms are mapped in. Does someone know by what mechanism that is done? Is it that it decodes cru bit 0 of all card spaces ( effectively every 128'th cru-bit ) and tracks if anything else is on? Assuming only one will be on at a time? Then is the remaining address space shareable if additional device memory addresses are fully decoded? --- Also, I've seen that cards could use crubase's below 0x1000 as long as they don't need to be found by a DSRLNK routine. Were any such devices ever produced? If there is no ROM it is seems to me it requires community convention to allocate crubases do not collide, or memory addresses within a shared crubase that do not collide. --- I've got a YM2413 (OPLL) FM synthesizer chip I'd like to hook up to the 4A... I'm just trying to decide how I want to make it addressable. The minimum requirement is 2 memory mapped write-only bytes. -M@ 1 Quote Link to comment Share on other sites More sharing options...
Tursi Posted February 17, 2019 Share Posted February 17, 2019 As it was explained to me, it pages in when there is a CRU access less than >1000. The idea was that then it was always available in (for instance) Extended BASIC, because the keyboard scan would switch it in. 3 Quote Link to comment Share on other sites More sharing options...
+helocast Posted February 17, 2019 Share Posted February 17, 2019 Ok, so I understand the SID Master 99 is mapped into the 0x4000 - 0x5FFF space when no other DSR roms are mapped in. Does someone know by what mechanism that is done? Is it that it decodes cru bit 0 of all card spaces ( effectively every 128'th cru-bit ) and tracks if anything else is on? Assuming only one will be on at a time? Then is the remaining address space shareable if additional device memory addresses are fully decoded? I agree with Tursi as I don't see much on the card in the way of decode, but I did find a small snippet of what I'm assuming is the manual: 2 Quote Link to comment Share on other sites More sharing options...
+jedimatt42 Posted February 17, 2019 Author Share Posted February 17, 2019 Oh, $@#$@, that is (possibly) a bit more intrusive than I imagined... So, I've just observed that running around in Easy-Bug where I commonly enable TIPI, the Sid Master 99 turns off for a moment, but then of course Easy-Bug prompts me again which (must) re-enables it... So technically I have 2 devices in the same address space right now. (from a high-level point of view) Luckily write-operations and read operations further divide address space electrically... or can, anyway... ok, so technically that answers the question about what crubases below >1000 are available... none... -M@ Quote Link to comment Share on other sites More sharing options...
+jedimatt42 Posted February 17, 2019 Author Share Posted February 17, 2019 Ah, with Helocast's data, I am overlapped when I debug TIPI in mini-mem, as tipi's output registers are at 0x5FFD and 0x5FFF.... my SID probably goes nuts very quietly when I'm manually testing TIPI... -M@ 2 Quote Link to comment Share on other sites More sharing options...
apersson850 Posted February 18, 2019 Share Posted February 18, 2019 My own internal (in the console) RAM expansion uses CRU addresses at >400 to enable and disable banks of that memory. I can enable RAM in the DSR space (and everywhere else) with a CRU access based at >400. This is just to prove that such assumptions as the SID Master 99 does are always dangerous. As is my own assumption, that CRU address >400 will not interfere with anything. 1 Quote Link to comment Share on other sites More sharing options...
+Vorticon Posted February 18, 2019 Share Posted February 18, 2019 Great info on the SID card. I have one and have never used it... It's a damn shame if you ask me, particularly since it can be easily accessed from almost any language. I wonder if an external version could be made so as not to require a PBox... Quote Link to comment Share on other sites More sharing options...
+TheBF Posted February 18, 2019 Share Posted February 18, 2019 What does a SID 99card do? Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted February 18, 2019 Share Posted February 18, 2019 What does a SID 99card do? This from Marc Hull’s website: What is SID Master 99? Sid Master 99 is a PEB interface cards that integrates an MOS 6581 or MOS 8580 SID chip into the architecture of the TI99/4A as a memory mapped device. It can be accessed through any language that allows normal CPU memory access such as assembly language, Extended BASIC etc. If you can do a CALL LOAD or equivalent then you can access the SID chip. A new vista of never before heard sounds can now be played through your TI99/4A. No sound cables required. It is completely compatible with the existing sound chip on the computer and plays through your monitor or TV. ...lee 1 Quote Link to comment Share on other sites More sharing options...
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