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Recent content by JGardner

  1. J

    Warning: Spaghetti Code...

    What's all this embedded code stuff, anyway? Why not just use GETMEM and read the code <from> the DATA statement into RAM? Because - The guy I wrote this for has a super-rare "Tiger-Stripe" CC40 pre- production model, with only 2K of RAM installed, & I'm hoping this 800 byte pgm will...
  2. J

    Fun with CC40s

    I've been poking around in ROM, trying to learn a bit more about Hook tables in System RAM. A few years ago Acadiel asked me to write a pgm to dump the CC40 system ROMs - I'd thought the 4-8K ROM pages @>D000-E000 were accessible in DEBUG with the "R" command, but this turns out to be...
  3. J

    Updated Ed Hallett CC40 cartridge port map...

    Items in brackets are my additions.
  4. J

    Fun with CC40's

    512 KB RAM, <and> blinkenlights... Does it get any better? :)
  5. J

    Fun with TI-BASIC - Is it a bug, or a feature?

    Piddling around with a 74 the other day, I noticed that invoking ON WARNING does not intercept the "W3 at ### Mismatch" warning thrown if you try to ACCEPT a null field into a numeric variable - What I was up to was trying to use ON WARNING ERROR to process the warning with a CALL ERR()...
  6. J

    Wafertape

    Some of you guys have these things - I've built a Wafertape emulator, which I'm hoping you'll help me test. AFAICT the device responds appropriately to Hexbus commands - If you have CC40 software that was supposed to work with a Wafertape and are willing to share, that'd be a great help...
  7. J

    Fun with TI-74s - Hamming codes

    Error-correcting codes are a fascinating subject, despite the occasional tendency for eyes to cross while enjoying their mathematical derivations... :) Richard Hamming also later gave us two classics, "Numerical Methods For Scientists And Engineers", and "Digital Filters" - By all means...
  8. J

    speaking of vintage computers...

    http://en.wikipedia.org/wiki/Apollo_Guidance_Computer Whatever we paid those guys (the crews) it was'nt enough... :) 45 years ago - Seems like yesterday. Well done, gentlemen!
  9. J

    W8.1 tablet / HP 200LX file transfer...

    Installed DOSBox .74 on the tablet, set Dosbox serial port config (run the Dosbox 0.74 Options batch file in Dosbox directory), mounted a directory containing CPACK FLOPPY files: http://www.hp200lx.net/cgi-bin/modsearch.cgi?Query=cpack (follow the instructions to create it). Connect a...
  10. J

    Fun with Ti-74s - I2C

    Many useful chips use the I2C com protocol; the '74 is quite capable of dealing with them. An example is the highly accurate DS3231 Real-Time-Clock eval board from Macetech: http://docs.macetech.com/doku.php/chronodot_v2.0. The chip is available in SOIC from Digikey, for those who deal in...
  11. J

    Fun with TI-74s

    A Use for DATA statements not found by RTFM... BASIC is handy, and believe it or not, many of the I2C & SPI peripherals out there these days can be interfaced to the '74 with PEEKS & POKES alone - This is usually so slow that you'll quickly see the point of assembly language subroutines...
  12. J

    TI-74 BASIC profiler

    Ever wonder how you might break down where your code is spending time, or how long an individual task takes? If you have access to a scope, or better yet a logic analyzer, it's easy (A cheap PC-based logic analyzer works great.) The idea is to toggle a pin in the Dock-Bus I/O port when the...
  13. J

    Rs-232

    For perverse reasons, I'm bit-banging serial async on a HP 200LX. I've done this many times before with microcontrollers - Disable interrupts, send your start bit, wait for the next bit frame, send b0, wait for next bitframe, send b1, and so on. Pretty simple. But it seems that globally...
  14. J

    Doc-Bus protocol...

    Logic analyzer screenshot of [ OLD "100.Boo.pgm" ] ...
  15. J

    fun with TI-74s...

    Default user memory "partition" in a Basicalc is at >4000, aka 0x4000h among the heathen... >4000 & up is cartridge memory, >3FFF & below is "System" RAM. 8K Cartridge memory can be appended to system RAM with [ CALL ADDMEM ]. Executing CALL ADDMEM with a 32K cartridge appends 8K - The...
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