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FarmerPotato

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About FarmerPotato

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  • Birthday 01/01/1971

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    TI-99/4A. FORTH. Verilog.
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  1. You could do it with a battery. A coin cell will run an LED for about a day. (no resistor needed to limit current). Two AAs will also do it.
  2. To get the resistor value, test them out with an external power source starting with 330 ohms. SW1 +5V -o_|_o----+------------------------ | | R1 R2 | | --- --- \ / LED1 \ / LED2 --- --- | | GND ----------+--------------+------- 1. See this easy guide: https://learn.sparkfun.com/tutorials/light-emitting-diodes-leds/all To avoid any math, that guide says "start with 330 ohms resistor, then adjust." There is a voltage drop across the LED. It depends on the color. In my experience, red is the least, blue or violet is the highest (I don't remember white) sometimes too much for a coin cell battery to provide. With math, Light up the LED using that 330 ohms, get out a voltmeter and measure the drop across the LED leads. Call this V_led. If you like this brightness, compute the current I_led: Assuming VCC is your test power voltage, then I_led = (VCC - V_led) / R. If you tested with one VCC, like 3V or whatever, and the console will provide 5 or 12V, you need to recalculate a different resistor to keep this brightness the same. 2. Doing it another way, work backwards from that current, OR the current listed on the package (that assumes you got a package, not just piles of random LEDs from China.) Your LED might need around 20 mA. Solving for R, assuming VCC=5 and V_led = 1.5, then R = (VCC - V_led) / I_led = 3.5 / 0.020 = 175 ohms. You would grab a 150 or 180 from your assortment of resistors. To understand where those standard ohm values come from: http://www.resistorguide.com/resistor-values/ 3. In the 4A, I dunno where to best hook them up, but any VCC pin will do, preferably close to where the power connector hooks up. One thing though: connect each LED with its own resistor. Each LED+Resistor goes in parallel, like the schematic above. If you put them in series, the sum of voltage drops will be too much. If you put all the LEDs in parallel after just one resistor, some won't turn on. 4. Much bigger project: TI makes a great LED driver chip, the TLC5940, which even lets you calibrate each LED's brightness and save it in EEPROM. I use these to drive an array of tiny laser pointer red LED lasers - which all have different V_led (and worse, they die easily if they get too much current.) At run-time you can set value for each brightness. The TLC5940 doesn't care how slow your input is, so it could be interfaced using 3 of the 9901 pins (the essential signals are XLAT, GSCLK, and SIN.) GSCLK can be connected to the 4A's PHI3 clock, or the 3.5 MHz clk out of the 9918A. One TLC5940 drives 16 LEDs, so you could have a bank of LEDs on the function strip. Software could turn the on individually or blink them. http://www.ti.com/lit/ds/symlink/tlc5940.pdf Search eBay for TLC5940 DIP because apparently the DIP is no longer offered.
  3. https://www.theverge.com/tldr/2020/2/25/21147389/jif-peanut-butter-giphy-settle-gif-pronunciation-debate
  4. For others following along, we do have a lot of good documentation in the CC-40 Editor Assembler manual here: http://ftp.whtech.com/hexbus_cc40_ti74/CC40 Editor-Assembler/ Here are a few facts from chapter 6: 0000-007F Register File (R0 is a byte at 0000, R127 is at 007F) 0080-00FF Unused 0100-01FF Peripheral File (Memory Mapped Devices) P0 to P127 0200-07FF Unused 0800-0FFF Built in 2K RAM 1000-4FFF Built-in RAM, up to 16K (Cartridge RAM can be paged on top of this) 5000-CFFF Cartridge ROM or RAM up to 16K D000-EFFF System ROM (8K pages from 32K total) F000-F7FF Unused F800-FFFF Processor ROM (onboard TMS70C20) Examples of Peripheral "File" registers: >104 is a read byte from keyboard rows >106 is the keyboard col selector >11E and >11F interface to the LCD display >119 System ROM bank# (2 bits) and cartridge bank# (2 bits) Addresses D000-EFFF would be the OS in 8K pages. Routines are documented in the manual. The 2K of processor ROM is the "BIOS" which initializes the system and enables all the memory banks. The manual is unclear about the differences in paging the two cartridge memory areas. Pages 6-15 and 6-16 are missing, presumably saying more about interrupts and the timer.
  5. Mike Dudeck has one more NIB Memo Processor. I’m re-colllecting HexBus items, so I bought one. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F372913095491 for those who don’t yet know, Mike has been selling NIB items and accessories for 20+ years. a lot of people got NIB p-boxes that way. I understand he (long ago) bought out LL Conner or Joy Electronics, who used to advertise in Micropendium. .
  6. I hoped to have a February progress report on 2/20/2020, but what I have is: 1. The V99958 board has been sent to OSH Park. ETA Mar 4. 2. Instead of sending the CPU board to OSH Park, I am laying it out again as 3 separate boards, with a nice clean bus. CPU has ports for FPGA bridge and 2 cards. Separate Memory and CRU cards. Memory module is interchangeable between a simple 128K BIOS, or a later bank-switched module with higher chip-count. Where does the VDP, Sound, and 2-32MB DRAM go? Those all connect to the FPGA board. I considered making it a 4 inch cube with backplane and 6 cards, but I'm sticking with lays-flat-on-my-workbench. This *is* just a prototype. Working prototypes will be open-sourced (as will the entire project). 3. Sound card (FM) will have at least two YMF262 OPL3, and SN76489. 4. Negotiating for some IP. 5. Delayed by puppies. 6 out of 7 puppies are adopted out. Remaining puppy ran off with a 4A transformer. Whew. Code name dictionary Sapphire - CPU module Garnet - Sound (FM) module Pearl - VDP module Steven - FPGA module Lion - Memory module Connie - CRU module + RS322
  7. Thank you for doing this. And it's awesome that your first PCB passes all the tests!
  8. After reading the Greenberg document, I had these questions: 1. Is Greenberg writing as the author of the BASIC interpreter source? Or just a consultant on the documentation? 2. How many ideas did he bring in from other BASIC interpreters? 3. When did DX BASIC become a product? 4. Did Greenberg write both documents? 5. Why no Section I of the Greenberg document? Ideas about DX BASIC in general From bitsavers, I see the BASIC 4.0 manual in 1983. http://www.bitsavers.org/pdf/ti/990/basic/ Since the Feb 78 TI-990 catalog has Item 243 BASIC in an essentially finished form, the June 1978 Specification is a description written long after the DX10 BASIC shipped. Item 244 Business BASIC has a different choice of features from the spec (see Subsetting p.160) http://www.bitsavers.org/pdf/ti/990/brochures/990_Computer_Family_Catalog_Feb78.pdf The Mar77 brochure also offers Multiuser BASIC (along with FORTRAN IV, COBOL, and assembly language.) http://www.bitsavers.org/pdf/ti/990/brochures/ Two hypotheses about Greenberg: Greenberg wrote a new BASIC interpreter described in his source documentation. Greenberg consulted on system documentation to support a extension or a port of the existing DX BASIC.
  9. I wonder how many copies of these files escaped TI? I wonder if it is the same version I know of? I know that the TI Writer and E/A GROM source walked out the door when TI Lubbock laid off a certain employee in 1984. Said employee spent his last few days making some diskettes that included all this, concatenated together. I recall the name Bill Brewer, but I can't be sure if that's the employee or a local sysop that knew us both. I sent copies to a few people such as Paul Charlton and Matt Beebe. Maybe you too? When I last looked, my disk copy had some bad sectors, but I sent them (on Facebook) to Susan Bailey anyway. She appreciated that. This is a cleaner copy.
  10. Some folks have overclocked the 9900 to 4MHz. Thierry has info about doing that: http://www.unige.ch/medecine/nouspikel/ti99/clockup.htm There was the SBP9900 which goes to 4.4MHz http://www.cpushack.com/2015/02/05/ti-tms9900sbp9900-accidental-success/#more-19685 I think this is the 4Mhz rated S9900 part for $20 here http://www.unicornelectronics.com/backcorner/ic.html
  11. In my experience the quickest way to test that your found 9995 is working, in wire wrap, is to add 1 EPROM, a LS138 decoder, and the SN76489 sound chip. Take some 99/4A sound or music-playing code - change the WS pointer and the >8400 pointer and it should run. (Oops, I forgot that I used the 60Hz VDP interrupt and INT1.. you could use a simple delay loop at least. Or test the internal timer.) I felt more confident after executing a program that writes sound list bytes to one address. Then move on to 9902 since you know that code executes correctly. Plenty of sample code is out there. Here's Thierrys documentation and sample code. If you need a new 2x20 wire wrap socket, I got this batch from eBay shipped from Canada, about $3 each. (I can share these and 9902.)
  12. Could it be a modem? Can you see if any of the 18-pin ICs are a TMS99532 modem chip? Other possibilities I can think of: a door entry panel, a radio tower remote controller. It seems to interface to a backplane through buffer chips.
  13. I have China 9902s from polida2008 (eBay). I can send you some. I have not tested them yet. You can follow Stuart Connor's design to use any MAX232 (TI even makes them) to make the signal EIA-RS232 levels. Or just get a TTL serial cable ("FTDI") to hook up to the RX/TX/CTS pins. Another idea, which I have not got to yet, is to divide down a 8.192 MHz oscillator and match 115,200 baud exactly. The 9902 with a 3Mhz input can't quite get it. Probably safer though, going with the TMS9995 3 MHz clock out and 9600 baud.
  14. Thanks for doing this. You have vivid memories of all of these? I'm glad you're here.
  15. Here is another diskful, found one by one on music disks from the MATIUG library (searching volumes 1-180) SAMMOORE3 : 419 used 301 free 180 KB 2S/1D 40T 9 S/T ---------------------------------------------------------------------------- DOG-GONE 38 PROGRAM 9315 B MAINSCREEN 17 PROGRAM 3925 B MOM_GOOSE 37 PROGRAM 9140 B MOONLIGHT 49 INT/VAR 254 12141 B 48 recs MORNING 40 PROGRAM 9879 B ORGAN 38 PROGRAM 9405 B PIANO 30 PROGRAM 7240 B R-BOOGIE 17 PROGRAM 4027 B ROBOT_JOKE 27 PROGRAM 6551 B SPACEGEM 11 PROGRAM 2379 B TRUCKER 23 PROGRAM 5598 B VENUS 26 PROGRAM 6297 B W-BOOGIE 26 PROGRAM 6257 B WAY-YOU-R 38 PROGRAM 9437 B Not all are music. Trucker is pretty funny. sammoore3.dsk
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