Jump to content
Have You Played Atari Today?
2600|5200|7800|Lynx|Jaguar|Forums|Store  

JayoK

Members
 View Profile  See their activity

  • Content Count

    213

  • Joined

  • Last visited

Posts posted by JayoK

  3. Posted

     

    I've done the 800XL clearpic mod but wasn't happy with it and backed most of it off.

     

    I suspect that NTSC mods don't necessarily turn out the same on PAL systems.

     

    But, I've added S-Video and 3.5 mm audio to the 130XE... a pretty easy mod. I went the S-Video route mainly because I run the Atari through my capture card and the S-Video wasn't being used for anything else.

     

    I'd recommend just a straight pair of RCA jacks for A/V for hooking to a 1084S or VCR (ie - you'd effectively be giving your machine the XEGS treatment). Just get one of those RCA splitter plugs to duplicate the mono audio for the dual speakers.

     

    If you're doing that mod, then it's just a simple case of grabbing the outputs you need straight from the monitor port.

     

    Or you can just build or buy an external adaptor.

     

    Thanks Rybags - I was going nuts trying to find this.

     

    Good point about the RCA jacks - I will probably throw a better cable together.

     

    Growing up, I was used to the 800XL on a TV screen over RF. Plugged it finally into a 1084S this year and couldn't believe how good the picture was. Years of a foggy image left me with low expectations. Looking forward to the upgade now.

  5. Posted · Edited by JayoK

    Ok from Mapping the Atari:

     

    BIT 2 [of SKCTL $d20f] is first set to zero to reset POT registers to zero (dumping the

    capacitors used to change the POT registers). Then BIT 2 is set to

    one to enable the fast scan. Fast scan is not as accurate as the

    normal scan routine. BIT 2 must be reset to zero to enable the

    normal scan mode; otherwise, the capacitors will never dump.

     

     

    I knew it was necessary to control this capacitance with paddles. Although you are reading this from the shadow register this shouldn't be a problem... I think it might be your circuit.

     

    Fast scan occurs in two scanlines normal scan occurs in one frame (228 scanlines). Not an issue unless you are doing high-speed sampling. Also fast pot scan is less accurare than a normal scan.

  7. Posted

    I am really trawling the long term memory now, but I believe that the fast pot scan is to do with sampling the value without allowing full-discharge or something like that... cannot remember the exact details. As I've just moved house De Re Atari is packed away at the mo.

     

    I think the problem you are experiencing those is that the there is no where for the charge to go once the port is loaded (capacitance and all that). The paddle1 inputs were designed to read potentiometers (sp?) not variable resistors.

     

    BTW I still then the latch is a way to get more inputs, I used this method to get 16 in a band switching fashion.

     

    Right time for me to find De Re Atari then...

  9. Posted · Edited by JayoK

    I want to use the paddle input to detect when a switch is closed to ground. I've used up all the port and trig inpus already - so I can't do it that way. The way I have the circuit set up is one end of a 4k resistor to +5v and the other to paddle1 input, then 1 end of switch to ground and other to paddle1 input. Then I do a LDX $271 - CPX #228 - BEQ routine. This work most times but sometimes gets stuck <> 228. Is there a more reliable way to do this - fast pot dump, or checking a register before I read it.

     

    Just looking at your post again - is your circuit ok? I think paddle1 input isn't discharging quick enough after the initial load. I would try a design like this:

     

    +5v - 10k - | - 10k - GND

    |

    -- Switch - GND

    |

    Paddle1

    input

     

    I did try something like this a long time ago and remember having to using a similar circuit as above.

  10. Posted

    I want to use the paddle input to detect when a switch is closed to ground. I've used up all the port and trig inpus already - so I can't do it that way. The way I have the circuit set up is one end of a 4k resistor to +5v and the other to paddle1 input, then 1 end of switch to ground and other to paddle1 input. Then I do a LDX $271 - CPX #228 - BEQ routine. This work most times but sometimes gets stuck <> 228. Is there a more reliable way to do this - fast pot dump, or checking a register before I read it.

     

    Instead of CPX #228 how about detecting if it is between a range? I would imagine that with component tolerance, heat, etc that always detecting for 228 is too narrow. Also I do remember that the paddle input won't work particularily as a high-speed input. Also I'd read the hardware register not the shadowed one.

     

    As an alternative to the design, did you consider multiplexing the inputs, or maybe using a latch read method? Might be too complicated for the design.

  20. Posted

    Hi Sluggo,

     

    As for 800XL-A it could be anything, OS, keyboard, RAM, etc. If the chips are socketed and the systems haven't been used in a while check to make sure the contacts haven't oxidized (or maybe you've done that). It may also be wothwhile to disconnect the keyboard anyway to test the other machine.

     

    For my old XL I'd to do remove the socketed chips and clean the contacts (using nail polish remover!). Once re-inserted and off I went again.

     

    As for XL-B sounds like the KB, again check the contacts. You could though quite easily swap keyboards from A to B to test the function key theory. Do all other keys work?

     

    Let us know you you get on!

     

    Jayo.

  22. Posted

    And here I was plotting secretly in the back ground an A8 Bubble Bobble... little did I know that others were working on it :roll:

     

    Cancel that project.

     

    I need a little help here folks, I used program my A8 years ago and only recently returned and I would like a little project as a refresher - would any of you suggest something that I could work on that you would like to see?

     

    My plan with BB was an intro screen, music and just say 3 levels as a proof-of-concept type of thing. So I suppose something like that would be cool, any suggestions?

  23. Posted

    A delayed response I know, but just back from holidays and only getting to this now.

     

    As for the pin outs on the TT I assume you mean the 9-pin connector? Don't have them exactly but I can give you some help here. The TT pulls power from the +5V line on the joystick port and feeds back in the X and Y position using the pokey pots in. The trigger buttons are also made up of the PIA 0-3 or 4-7 lines. i.e.

     

    Placing the pen in the bottom in one corner should give a 0,0 (doing this from memory and I recall that the unit worked in reverse) on the POTS readout.

     

    If you are coding for this information bear in mind to allow for tolerance as the resolution of 255 in one axis is quite what this unit can do.

  24. Posted

    I know this is a little off the subject of what you were looking for, but out of point of note. I remember writing a Motorola 6800 emulator on the 8-bit back in 92. What was the point of that? Well I had to develop a 6802 system for a project and the cost of commercial emulators was outrageous. Based on DDT from Mac/65 this thing could step through the 6802 code and show the registers, memory locations, etc. Only thing was it only emulated 4k RAM and 4K ROM, but then that was all I needed! Worked fairly fast too.

     

    Another point of note I won five awards for the project as a result - including best development system! :)

  25. Posted

    Actually thinking about this some more.. this code could be very easily written. As a test you could do something like this in BASIC

     

    10 OPEN #1,6,0,"D1:PRINTME.TXT"

    20 OPEN #2,9,0,"P:"

    30 TRAP 80

    40 GET #1,A

    50 IF A=155 THEN A=13

    60 PUT #2,A

    70 GOTO 40

    80 CLOSE #1: CLOSE #2

     

    Ok, so the OPEN syntaxes may not be right but you get the general idea. For the P: driver you need to locate the IOCB table and the corresponding code for putting out a byte to the P: device. I would image that the code somewhere would have LDA BUFFER, STA POKEY_OUTPUT. You could circumvent this with a small patch. Replacing like this

     

    ** LDA BUFFER ** Removed

    JSR MODIFIED

    STA POKEY_OUTPUT

     

    .ORG $00D4 ;in page zero but could be anywhere

    ;don't use FP when printing

     

    MODIFIED

    CMP #155 ; is it Atari EOL?

    BNE RETURN ; Nope then just continue

    LDA #13 ; It is then replace 155 with 13 (EOL)

    RETURN

    RTS ; all done, return!

     

     

     

    So what have I done here? Got carried away, that's what! The code is not 100% accurate as I don't have any of the coding books with me at the moment but you probably get the general idea.

     

    One final option is to reprogram the HP printer character set, now that's a whole mountain of work. :)

AtariAge
Forums
Store
General
Follow AtariAge

Copyright ©1998-2021 AtariAge

×
×
  • Create New...