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Lee Stewart

Member Since 7 May 2011
ONLINE Last Active Today, 3:43 PM

Posts I've Made

In Topic: "Programme fuer den TI-99/4A und TI-99/4"

Sat Apr 20, 2019 6:28 PM


(Is it possible to play with keyboard on Classic99?)


Yes.  For details, see §5.2 “Joystick” in the Classic99 Manual:  From the menu, select “Options-->Options...”, then mark ”Enable Joysticks” and click each joystick you want to control through the PC keyboard.  The arrow keys are the directional keys and Tab is the Fire button.



In Topic: Satellite tracking program for TI-99/4A

Tue Apr 16, 2019 3:17 PM

I use John Walker’s (founder of AutoDesk, Inc. and coauthor of AutoCAD) Home Planet, available from his website, Fourmilab, based in Switzerland.  The Home Planet C source code (Visual C 7.0/Visual Studio .NET) is available on the site, as well.  It might offer some insight for an energetic programmer.



In Topic: now that I got my Ti going, what's the most optimal upgrade path?

Sun Apr 14, 2019 3:54 PM

NanoPeb is still out of stock correct?
finalgrom is also?


Arcadeshopper.com has them.  The nanoPEB is currently out of stock, but periodically comes back in.  They sell out fast.



In Topic: Thierry Nouspikel

Sun Apr 14, 2019 3:40 PM

Sending PM in a sec.



In Topic: CALL FILES/subprogram >16 code

Sun Apr 14, 2019 1:09 PM

Lee, I wrote some code for updating the file buffers at the top of the VDP RAM that I erroneously called PABs.  But now where are these "linked PABs" of BASIC that >833C should point to?  That address contains 0 after entering BASIC.  EDIT: Is the OPEN command in the DSR handling this?


I also had another look at the TIFC, and for that device at least >16 and FILES are identical in function.


Again, the DSR knows nothing about a linked PAB list.  The PAB that TIB or XB sets up for a given file has all the information the DSR needs for OPEN or any other file-dependent opcode.


When TIB or XB start up, there are no PABs, so >833C contains 0, signalling that such is the case.  This (0) is the same value as contained in the list-link-pointer address (first two bytes) of the last PAB in the chain, signalling the end of the chain.  The PAB chain starts after the space allotted to the Value Stack, whose base pointer is >8324 and top-of-stack pointer is >836E.  TIB and XB probably have a hard-coded start address for the start of the PAB list.  On page 302 of the E/A Manual, there is a suggestion that this address for TIB is >0FAB.  Based on the different sizes of the first two PABs, I would guess TIB and XB reserve space for a file’s data buffer immediately following its PAB.