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FarmerPotato

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About FarmerPotato

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    Dragonstomper
  • Birthday 01/01/1971

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    Male
  • Location
    Austin, TX
  • Interests
    TI-99/4A. FORTH. Verilog.
  • Currently Playing
    Last year: Port Royale 3, Pocket Trains, Minecraft, Master of Orion II, PacMan 256, Katamari Damacy, We Love Katamari, NY Times Crossword
    This year: Katamari Damacy Reroll, Settlers of Catan Universe, Chisholm Trail, NY Times Crossword

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  1. I don't have a Genesis, but I have Saturn. So I looked up the schematic for those. https://gamesx.com/controldata/saturn.htm It has two 74153 chips to select 4 of 16 inputs. https://gamesx.com/grafx/saturn.gif My understanding is the TI joystick port can output -0.5 (active) or +5V (idle) on one select line at a time. http://www.unige.ch/medecine/nouspikel/ti99/joystick.htm Pins TI Saturn NC 1 VCC 8 2 D1 Down, C 3 3 D0 Up, B 7 4 S0 (TI Joy#1 active) 2 5 S1 (TI Joy#2 active) NC 6 presence detector 9 7 D3 Right, Start 5 8 D2 Left, A ? 9 GND I don't see where you get a GND from on the joystick port. I guess this kills the idea. At least on the Genesis it's possible to ignore the mutiplexer chips and still get usable functions. For VCC I think you could charge up a capacitor+Schottky diode from TI pin 7 or 2. This avoids an external +5V. Then with the two Joy Active lines, you could select either of the rows ABCSt or UpDnLtRt. But not XYZR (can't activate both outputs at once). With no joystick select, you get the Left trigger. In all you get joy + 3 fire buttons + the Start button. Maybe the left trigger. SS Reads 00 Z Y X R 10 B C A St 01 UpDnLtRt 11 - - - L The 4A would need custom code to read the buttons. By default, it would work as a 4 way joystick with no fire button, but the buttons would read as directions on joystick#2. One area I don't have my head around is what happens when a joystick has a chip that actively drives an input? The 4A expects passive switches. The L trigger could interfere with keyboard scan - probably acceptable. But as I said, this seems dead if there is no GND pin, the multiplexers would go haywire.
  2. Seems I wrote a more detailed reply than I intended. And it's tough reality, not in the spirit of this "I wish for" thread. When choosing a PLD for my various projects, I looked at the whole ATF family. My goal was to reduce chip count without raising cost. Hence, the $1.33 22LV10. The ATF750 and ATF1500 are overkill for simple projects. It is a waste to use a 1500 as a line buffer (you would consume its 32 I/Os in pairs.) The 4A has 16 address lines, 8 data lines, and 6 control lines to buffer. The 1504 barely covers this. Using more PLDs removes the product ever further from "I can see what it does by looking at it" principle. In favor of the 1500: 1. Available for $3 2. PLCC44 3. Elegant capabilities and registers. It is a pretty good match at being a logic chip (in the SAMS it would replace a bunch of chips.) 4. The 1504 is an upgrade to it for a few cents more. The drawbacks of the 1500 are: 1. Requires a $300 investment in a programmer to use the 1500. It is not supported by the cheap TL866. 2. Horrible programming tools stuck in the Windows 95 era and never debugged. So, the 1500 barely makes sense, if 1 or 2 22LV10s can do the job. The 1504 looks better but has those drawbacks too. The 1508 has all the above and more drawbacks: 1. High cost ($12) compared to what you get. MachXO2 and ICE40HX CPLDs for the money give 10X to 100X the capability, also replacing the LS612 in software. Overkill for the job. 2. Monster size. PLCC84 is the smallest. The only advantage the 1508 has over chips that cost less than $12 is being more 5V safe.
  3. I took the 4x7" figure as a challenge. Here are my rough sketches for a 1MB SAMS on the JediMatt42 connector, which fit into 100x100mm for DIP, and 70x100mm for some surface mount. The logic chips are condensed into one ATF22LV10C. This uses my favorite parts. The 100x100mm is the magic figure for DirtyPCBs $2 per board. I know there are some things missing - I said it was rough. BOM - $25 using some SMD. 2 PCB 4 LS612 2 LVC245A x 4 10 AS6C4008 x 2 2 ATF22LV10C 2 2x20 Long Pin Female socket 1 PLCC-28 socket 2 misc == 25 Then I found some LS612 for under $1 too good to be true in PLCC44 - and thru-hole PLCC44 sockets are easy. So here is an iteration. 2 PCB 7 LS612FN ? 2 LVC245A x 4 10 AS6C4008 x 2 2 ATF22LV10C 2 2x20 Long Pin Female socket 1 PLCC-28 socket 1 PLCC-44 socket 2 misc == 29
  4. Only $78 to go! Anyone want to donate a mug or a tote bag to our next donor?
  5. Would there be interest in a custom arcade-style controller box? I have made one with real arcade joystick and 2 buttons. It would be feasible to manufacture a kit for about $50. One or two joysticks. Two buttons, your choice of colors. I imagine a switch to assign both buttons to joystick#1, or #1 and #2. The arcade joystick is the most expensive part. The sides and top are wood (1/8" baltic birch color with laser-burnt edges) or some color of acrylic. The bottom is removable. There is a second plexiglass layer on top. You can put custom artwork under the plexiglass (I put Dragon's Lair.) The DB9 connector is screwed flush into the side. A DB9 extension cable is used to connect it to the 4A. All the wires inside the box have push-on spade contacts to the arcade joystick and buttons. The hardest part of assembling mine was crimping the DB9 pins. I would not do that again. Solder cup is much easier. However, making a litttle circuit board would make it even easier for the end-user. Repeat, these would offered with some-assembly-required. For wood, you need wood glue, and you paint it yourself. For acrylic, you need special solvent (I guess I could glue acrylic for you... bigger shipping box though.)
  6. I see we have $178 to go to reach the goal to pay for the conference rooms! I will MATCH the next $50 in donations. So step up, make a donation! Go here: https://locu.li/CTIFriday
  7. I have a double that I can share. It is Friday, Saturday and Sunday nights. Opry99er gets first dibs. BTW. the group rate only shows King (single) available in our block. But the Hilton Honors program can get you a double reservation for the same price as our group rate. I did that.
  8. BlackIce MX has fewer GPIO pins (48), and replaces static RAM with SDRAM. So you need some more code before you can get RAM up and running. The BlackIce II went out of stock more than a year ago. MX is about the same price. MX was created to be more friendly to builders who want to drop it into their own "carrier" board alternate to the simple one provided. I had a triple-PMOD on BlackIce II connected to the 4A side port, providing SAMS memory and memory mapped devices. I had to redesign it for MX to use just 16 pins, but I'm still using it on the II for the static memory.
  9. The 990 had a Memory Management module that added 3 segment registers to a process, but not to expand memory, rather to give each process up to 64K of its own protected memory in a 1 megabyte space. The vestiges are the 99/4 assembler support for LMM, LDS,LDD. IAQ is used in the 990/189 board to synchronize the release in hardware of a one-shot NMI with a 9900. A problem you solved in software. 9900 doesn’t identify arguments fetched with IAQ. Only the 99000 lets you separate code and data space through bus status codes.
  10. As I see it, any paged memory system in a cartridge is a unique scheme used by the software built into that cartridge. There's the case of 512K carts that say "FinalGROM required" but as far as I know they still use the Guidry bank scheme. The cartridge port is just too limited - it can't provide the main 32K CPU RAM, except as a one-off like Tursi mentioned where you add wires. Besides, putting a peripheral on the side port is easier. There's no demand for an "operating system" or extension that allocates pages, because there is no multitasking software for the 4A. Every program takes over the full hardware. SAMS Contest We already have a memory standard. SAMS cards have been available or made over the past 10 years. The AMS standard uses a mapping chip made by TI. What if we had an AMS contest in 2020? for hardware or software that use the AMS standard? So far, adamantyr is winning
  11. Talking about a display peripheral for CC-40... The ExelVision extended the CC-40's architecture of TMS7000 with the TMS3556 videotex processor. It reminds me of a VT340 terminal, but also with bitmapped graphics in 8 colors or greyscale. I spent a pleasant afternoon learning all about that chip when humeur posted the ExelVision thread. I found a thread indicating the TMS3556 appeared in the Roland S50 Sampler. http://www.vintagesynth.com/roland/s50.php https://www.ebay.com/itm/ROLAND-S-50-Sampler-Keyboard-Original-Main-Mother-Board-Works-Great/183926272091?hash=item2ad2dc305b:g:ENsAAOSwZF5ctZe9 Despite my childhood hours spent with the CC-40 I have no desire to work on it.. unless someone were to perfect a HexBus mass storage device, in which case I might get back into HexBus in 2021! I looked for the HexBus buffer chips, but they seem to have vanished in 1983 without ever going into wider distribution.
  12. Question: can a BML span 256 pixels wide? Or is 255 the limit? This is relevant to hiding 4 rows during scrolling and provide a non-scrolling status area with a little video running (not tile based). Or should I just use the scanline / GPU to turn off TL1 and 2?
  13. Yeah reverse thrust is malfunctioning . the flight computer barfs, math errors.. Try Joysticks?
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