CJ wrote on 13.02.09 at 21:32:47:


Yes.  I have PSP4 here, ...all 4MB of it.  GIMP (Linux) for everything else.  Can't stand Windows now having used it on and off, it's so bloated and laggy.

PSP4 also does the Amiga format, .IFF I think it is.  So you can easily convert graphics and alias on a modern PC to the ST.   

CJ wrote on 13.02.09 at 21:42:36:


Noooo!!  You're 6-feet tall and with a washboard stomach.  You all are.

Yes that's fine.  I can't complain can I, you wrote it for me in your own time!!    

Ultimately I intend to use it as a template and recompile it.  That's where I'll go next.

It's main purpose for me is to hook up these JeSTs when the PCBs arrive.  At the moment with PeST, I use sysinfo which recognises right clicks and brings up the help menu.

I'll likely put a counter in there too, hooked up to the clock timer, which counts how fast the autofire is running.  Then there will be another which counts how fast the left right left right (joystick waggling) is running.  I can go upto about 50-times a second, but if the ST falls over at 20-times a second..  The mouse for example will go all over the place if you clock it too fast.  Just to pull out as much conceivable information about the port.  But that's for another day when I have all of these other jobs out of the way.

The 4-bytes, yes.  I'm used to viewing data like this when working with a scope.

God no, I'm not complaining.  You know I once used to and was really volatile, but you just kind of reach a point where it achieves nothing.  Far far easier and less stressful to just get on with everyone and fit in.

The attached file, ...when I find it...  The first one is of the Atari joystick interface itself, with the first top 4 being the directions, and the remaining 2 being the fire buttons.  Where they start oscillating is the autofire.  The traces at the very bottom are detailed in the next paragraph.

The 2nd one is the PSX packet itself.  It's a slight variation of the duplex SPI method.  D0 is CSEL, D1 is clock, D2 is CMD, D3 is DATA, D4 is ACK.  There's enough clocks there for 5-bytes.  Which is a single PSX digital packet, taking about 600uS where JeST is concerned.

All totally irrelevant stuff, but hey I like looking at them.  That thing cost me £500!!!!  

JeST sits in the middle of those two running at about 1MIPS dependent on instructions and jumps.  Some of the decision making is a bit cumbersome as with only 35 RISC instructions there's no branching commands like IF.  It's all done with the overflow flags and shifting bits left and right and checking them.

All bit banged.

;------------------------------------------------------------------------------
;Subroutine : PSX_RW_BYTE
;------------------------------------------------------------------------------
;Passed : W contains byte to be transmitted
;Valid : N/A
;Uses : psx_tx_byte_ , psx_rx_byte_ , loop1_
;Returns : Byte received in W and psx_rx_byte_
;Error Code : N/A
;Error Trapping : N/A
;Outline : SPI style byte transfer
;------------------------------------------------------------------------------
PSX_RW_BYTE
    MOVWF   psx_tx_byte_

    MOVLW   8d									    ;we will be transferring 8 bits

    MOVWF   loop1_
Psx_rw_byte_next_bit:
    BCF     PORTB,   PSX_CLK_PORTB_O_						 ;bring clock low

    RRF     psx_tx_byte_, F							   ;put transmitted data on bus

    BTFSS   STATUS, C
    BCF     PORTB, PSX_CMD_PORTB_O_	  
    BTFSC   STATUS, C
    BSF     PORTB, PSX_CMD_PORTB_O_

    BSF     PORTB, PSX_CLK_PORTB_O_						 ;bring clock high

    BCF     STATUS, C
    BTFSC   PORTB, PSX_DAT_PORTB_I_						 ;get received data from bus

    BSF     STATUS, C
    RRF     psx_rx_byte_, F

    DECFSZ  loop1_, F
    GOTO    Psx_rw_byte_next_bit						    ;next bit

    BSF     PORTB, PSX_CMD_PORTB_O_						 ;set COMMAND high	  

    MOVF    psx_rx_byte_, W							   ;value returned to caller

    RETURN
 

Oh wow!!  Almost as good as Omega Race.  

I thought you meant;

 

No worries on timing.  I really appreciate it whenever.  I'm pretty much on hold at the moment until the PCBs arrive next week, as that'll be when I start getting the timing variables right for the ST and Sinclair.  Might have to rework the PCBs I found out the other day too, should have put a pull-up resistor on there..

techie_alison wrote on 13.02.09 at 22:25:14:

Actually, I'm 6'2" http://www.atariage.com/forums/index.php?showtopic=2671&view=findpost&p=1097248  but who's counting?   

techie_alison wrote on 14.02.09 at 02:13:00:

Getting a scope is something that keeps banging around the fringes of my thoughts.  I barely know what to do with one, but I've had occasions where it would have been might handy.

Oh, and welcome aboard.  The fellows tell me that I must get a PeST interface...  

Right where were we.

Shw?  You want PSP4?  

And Remo, you want an oscilloscope.    It depends what you want to do with it really, as to which one you get.  There's 4 main flavours, that being an analogue scope which is literally volts over time, basically a CRT connected to a timebase.  A digital scope, which is almost the same but has a computer in it and can store things and go back and forth.  An MSO (Mixed Signal) which is digital and has additional LA (Logic Analyser lines in a scope type fashion).  That's what I have.  And finally an LA (Logic Analyser) which is much more advanced than the MSO, but doesn't have the analogue aspect.  

Each has their uses depending on what you want to do.  The Velleman scopes are pretty basic digital scopes with a tiny memory, but are fine for single line fault diagnosis and automotive stuff.  http://i31.twenga.com/3/tp/46/55/6046238802527484655vb.png .  £50 is about the going rate for those 2nd hand.  I almost always buy new though (about £90) unless it's silly cheap.

£80 at Maplin right now; http://www.maplin.co.uk/Module.aspx?ModuleNo=32611&doy=15m2&C=SO&U=strat15 .  They're pretty rubbish though except for anything other than audio signals and basic digital.  It's says 10Mhz but aliasing takes that down to about 2Mhz max.

techie_alison wrote on 15.02.09 at 00:45:21:

Thanks Aly, that does give me a bit more to think about.  I definitely want a digital scope, and there are times where a simple logic analyzer might be beneficial too.  I remember seeing a PC based setup that looked interesting as well.