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About FarmerPotato

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  • Birthday 01/01/1971

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    Austin, TX
  • Interests
    TI-99/4A. FORTH. Verilog.
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    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 spent May working on IceTea 0.2, now while I wait for boards from OSH Park I started laying out: Gemini - A Twin 9958 board to replace 9918. I started wondering how to best move data between screens, some kind of DMA maybe... I got the crazy idea to use 128K DRAM on each 9958, but, make the expansion 64K switchable. The first 9958 would use a block copy to move its data from main RAM to the expansion 64K. When the command finishes, the CPU would switch all the access lines to the other 9958. Hopefully this doesn't hurt the refresh cycle of the DRAM. The second 9958 would move from expansion RAM to the frame buffer in RAM. This would provide a way to flip a big chunk of data from one 9958 to the other. It's been 25 years since I programmed the 9938, so I forget whether there even is a block copy to expansion DRAM. Oh yeah, V9938 MSX-VIDEO USER'S MANUAL p 62 4.3 HMMM (High-speed move VRAM to VRAM The HMMM command transfers data in a specified rectangular area from the VRAM or the expansion RAM to the VRAM or the expansion RAM.
  2. Fest 99/4ATX will be held Friday August 9 to Sunday August 11. Details again: Dates are Friday August 9 to Sunday August 11. Costs for the event are: * A nominal charge for the 99/4ATX cartridge name badge, raffle ticket, snacks and drinks. * Breakfast or lunch on Saturday: group order of breakfast tacos and BBQ (County Line BBQ). * Otherwise open to free public walk-ins (I would expect others from the hackerspace and the local C-64 group.) Venue: ATX Hackerspace 9700 Dessau Rd, Austin TX. Has air conditioning, a kitchen, and wi-fi. Classroom and lounge for the weekend, at no cost. Guided tours of members only areas like 3D printing, metal shop, lasers etc. Format: BarCamp style. Attendees set up systems in the classroom or lounge or lobby. Anyone can schedule a presentation slot in the classroom or lounge, otherwise free form. Security: we can put gear in a locked room overnight. The building is keyed entry. Hardware: I can provide some P-Boxes, 4A consoles, monitors so you can travel lighter. Electronics lab available. Classroom has projection screen, whiteboard, giant monitor. Lodging: Super 8 near ATXHS is as low as $58. Marriot $118. There are a lot of options. Airport: Austin-Bergstrom airport ATX (sometimes AUS) Transportation: Volunteers can help with airport pickup; Uber is around $35. Food: Saturday: Breakfast Tacos. Lunch: barbecue delivery. Dinner: trip to Chuy's (Tex-Mex.) Lottery: badge holders only. One Dragon's Lair cartridge. Swap: bring items to sell or trade!
  3. Another thing. The 9958 has 15KHz analog RGB output. Monitors to display that on are scarce. I wonder if there is an inexpensive IC that would do the job of converting analog RGB to DVI? This one costs $45: https://www.analog.com/media/en/technical-documentation/data-sheets/ADV7403.pdf Old $4 TVP7002 from TI takes analog RGB (multiplexed! superimpose!) but outputs 24 bit digital color. You need another chip to code that into a DVI signal.
  4. Those are all good reasons to build this! I bet we could get Doug to patch MG Explorer to use two screens. I looked on page 104 of the V9938 manual, External Synchronization. I don't understand how to build the GenLock. I get that it is a PLL circuit. VDP1 HSYNC is input to the PLL. I don't get where the VDP2 crystal goes (is HSYNC from VDP1 already fXTAL=21.48 MHz? No, it's fXTAL/2.) Is there a suitable PLL IC you can just buy off the shelf? I see TI makes a bunch under $2. The SN74LV4046ANSR is a PLL and VCO . Combined with LT1675 high bandwidth switch, that seems to be a modern solution to external superimpose, for $10 in chips. Internal superimpose seems to be much easier. You need a single clock oscillator, but, according to this thread on msx.org So I imagine the following Superimpose use cases Twin 9958: superimpose VDP2 over VDP1, giving extra scrolling planes and sprites, or titling Video Production: superimpose VDP2 over external RGB for titling (No superimpose) These can combine with mirror and dual mode which are: Mirror Mode: VDP1 and VDP2 have the same graphics. Dual screen: VDP1 and VDP2 showing independent graphics screens. in either case, VDP1 is the console's default VDP.
  5. Executive decision gets made today. I have all the inputs in a spreadsheet. I'm considering the Texas replies and a slim majority favor Aug 10. "Official" Sloth of Approval has been requested from Amanda, Chief Sloth of Operations (originally Chief Sloth of Communications for our Bricklink.com store). Amanda will be doing logistics and really important stuff. She also does surface mount soldering and laser cutting.
  6. In the US, the film adaption aired on PBS as The Adolescence of P-1.
  7. I watched this game a lot as a kid. Mostly because no good at it. There was a cocktail version in the restaurant atop Pyramid Plaza in Lubbock TX. (My mental map had a lot of neurons devoted to where the arcade games were.) Sunware/Exceltec had an office on the ground floor. I like to think they came upstairs to play Omega Race.. but shipped Space Patrol.
  8. Microsurgeon is one of my favorites! Great idea, its due for a remake.
  9. See these techniques: https://en.wikipedia.org/wiki/Stereoscopy https://en.wikipedia.org/wiki/Anaglyph_3D
  10. On an 80s workstation, a second display might have been a dedicated frame buffer, especially if the primary display was monochrome (or low color) and the second was 24-bit color. Imagine that the two VDPs start up in mirroring mode - they always show the same thing. Technically, in mirroring mode, VDP 2 would accept the writes to VDP 1 but do nothing on reads. It would always be up to date with the same image as VDP 1. Normal equates - call these VDP 1 VDPRD EQU >8800 ; VDP read data VDPSTA EQU >8802 ; VDP status register VDPWD EQU >8C00 ; VDP write data VDPWA EQU >8C02 ; VDP set read/write address Additional equates - VDP 1 only VDPRD EQU >8810 ; VDP read data VDPSTA EQU >8812 ; VDP status register VDPWD EQU >8C10 ; VDP write data VDPWA EQU >8C12 ; VDP set read/write address Additional equates - VDP 2 only VDPRD EQU >8820 ; VDP 2 read data VDPSTA EQU >8822 ; VDP 2 status register VDPWD EQU >8C20 ; VDP 2 write data VDPWA EQU >8C12 ; VDP 2 set read/write address Once there has been an access to VDP 1 or 2 specifically at one of the new addresses, mirroring mode ends, VDP 2 becomes independent and responds only at its own addresses. VDP 1 responds at both the base address or the new VDP 1 address. Imagine this demo: 1. A utility makes a copy of your favorite EA3 or EA5 program, substituting VDP addresses with VDP2. External references to E/A utilities like VMBW are replaced with VDP2 versions. You open your favorite program loader, load the program. So far VDP2 has been in mirrored mode, so it shows exactly the same thing as VDP 1. But as soon as the program starts, it begins writing to VDP2 so VDP2 enters dual mode. The image on VDP1 shows the program loader screen as if frozen while the program runs on VDP2. You quit the program. The TI title screen appears on VDP1 while the program you quit leaves a frozen screen behind on VDP2. 2. A special EA3 or EA5 program loader has an option to choose which VDP to use. See #1. 3. Screen dump. While VDP 2 retains a mirrored copy of the previous program output, you run a screen dump program that retrieves the image from VDP 2. This would work even if you didn't have a second monitor plugged in. For instance, Super Sketch or TI Artist runs in mirrored mode, then you push a button to freeze VDP 2, quit the program, and run a utility to retrieve the image from VDP 2. 4. A specially written program uses both VDP1 and VDP2 for different purposes. Examples: 4a. help is displayed on one screen. 4b. a picture viewer puts the image on VDP 2. 4c. the FORTH cursor runs on VDP 1 while bitmap graphics go to VDP 2. 5. User switch. After viewing one screen of a program, press a button to freeze that display and switch to the other one. It's the same program, just captured at different moments.
  11. I can't of a way that two VDPs would help you run two programs, except for TI BASIC which might be flippable between two programs (however PAD contains some important info.) Also I foresee that two VDPs would need to coordinate (for instance only one can return data to the CPU at a time). I think two identical VDPs on one board would be simpler to build.
  12. So Stuart sent me a 9958 with the challenge to re-create a plug in video board upgrade. I built a 9938+9995 standalone wirewrap 30 years ago, so this is just fun, but it has been done before (OPA SoB, Dijit.) I got to thinking, what about a DUAL 9958? The VDP RAM ports could be switched to mirrored, or just one screen getting focus, or operated independently as two ports. That's seriously weird. What would anyone do with it? Support for a second graphics screen would be easy to add in environments like FORTH. Imagine instead of split-screen bitmap mode, you had one screen for text and coding and another for graphics. Or two TI BASIC programs operating out of separate VDP RAM, switchable with a button. Or the ultimate, a Munch-Man with a super wide screen.
  13. I am going with PLCCs, not SOIC. I got a lifetime supply of PLCC20 and PLCC28 sockets. There was a TL866II bundle for $84 with 15 adaptors, including PLCC20 to 44. When it arrives I'll determine what the SOP adaptors really are. 3.3V PLD in PLCC28 ATF22LV10C-10JU-ND $1.47 DigiKey 5V PLD in PDIP and PLCC28 ATF22V10C-15PU-ND $1.66 ATF22V10C-15JU-ND $1.66 5V PLD in PDIP and PLCC20 ATF16V8B-15PU-ND $0.89 ATF16V8B-15JU-ND $0.89 "J" is PLCC (J lead) 1.27mm (0.05") and "P" is PDIP 2.54mm (0.1").
  14. That's 6 to 5pm Central, but we have the classroom all night, so you wouldn't be left out. I think I will set up Zoom for videoconferencing.
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