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<1234567…34>
  • If you've got a real working MF128,IF1, and MDR combo can I ask a favour?So, if you do have a real Multiface 128, Interface 1, Microdrive and, oh yeah, a Spectrum (48k or 128k) that are all working, can I ask a favour...? …

    ... with:
    ;
    ; PRINT USR 32768
    ;
    ; a ... $5ced ; jump to shadow rom address
    ;
    exx ; ... exx ; restore return to basic address
    pop hl
    ... gethook ld bc,($00ec) ; return the address of HOOK-CODE in bc register
    jp jp February 2008 Hardware
  • Tutorial - learn machine code in 30mins[B][I]Message from the moderators[/I] - bigjon has requested that readers' attention be drawn to a better version of this tutorial, one which is easi…

    ... -running (over 32768) and memorable address in RAM
    ;initialise score ... 0 to 65355 in the BC register.
    We will write the ... value 0 into the BC register, ready to increase it by ... 0,0; "Your score was "; USR 33000
    Now RUN the ...
    bigjon bigjon November 2009 Development
  • Can a guy that traveled on the short bus learn machine code...Hmmm So after some soul searching I figured it was time to finaly nail spectrum machine code. Its so frustrating to sit infront of a basic listing w…

    ... you type in PRINT USR 61440 (or whereever you ... with a value
    Increment register BC
    Return
    < ... br /> [code]
    PRINT USR 61440
    [/code]
    address a value in C, ... copy the manipulated register to the BC register pair so it ...
    wibble wibble August 2013 Development
  • ZX rom type detectionHere is routine for fast detection of zx rom / computer model. [URL="http://velesoft.speccy.cz/other/ZXROMDETECT.zip"]http://velesoft.speccy.cz/othe…

    ... from fixed address in zx48 rom and return in BC register value 0 ... be code used via PRINT USR xxxx

    [B]RETURNED ... rom contain byte #BF at address (#004B). If byte is different ... +2 roms at address (#09AC).
    Routine return register BC=0-7 for ...
    velesoft velesoft January 2015 Sinclair Miscellaneous
  • Calling machine codeOccasionally I see on ZX computers (mostly the spectrum, but I think also the '80 and '81), how someone made their machine code and wrote the bytes i…

    ... USR 60000[/code]
    If the routine starting at that address ... leaves an integer in the BC register, then that ... also do
    [code]USR 60000[/code]
    if you ... see
    [code]RANDOMISE USR 60000[/code]
    Can someone ...
    wilsonsamm wilsonsamm February 2016 Sinclair Miscellaneous
  • How do i learn to programAll the years i had a computer the only one i could program was the Texas Instruments Ti99/4a and when using extended basic with its so simple sprite…

    ... a Spectrum. Each memory address stores a number from ... 201)
    Then type USR 32767 [ENTER] and you ... br /> Poke that in then USR 32767 again.
    This time ... the contents of the BC register pair when it returns ... LD (BC),A) and increases PC. In BASIC USR xxxxx ...
    cyborg cyborg January 2002 Games
  • Why Hex in place of Denary?Ok - most MC books / tutorials advocate the use of hex instead of denary. But the Speccy doesn't actually have a Hex converter so you need to write …

    ... /> The USR xx function always returns the contents of the BC register at ... /> PRINT USR 30004 will jump into the routine at address 30004. 117 ...
    So if the A register still contains 6 from before ... PRINT USR 30000

    where nn is the address you ...
    monty.mole monty.mole March 2004 Development
  • Emuzwin / Spin AssemblerHello lads. Wondering if anyone can help. I've decided to look into playing about with some code using the Emuzwin or Spin built-in assembler. Are th…

    ... are PRINT USR "address of machine code", RANDOMIZE USR "Address..." or LET L=USR "address...". There ... BASIC operates the USR function returns whatever the BC register is holding. So ... entering PRINT USR 60000 would ...
    dmsmith dmsmith October 2005 Development
  • Noob to Z80 needing +3 helpI'm quite new to z80 programming, but i'm attempting to write some kind of windowing system that will run alongside BASIC on my +3 with Kempston mous…

    ... whatever was in the BC register pair. To communicate parameters ... br /> [code]
    let r = USR 32768: REM move 3,100 ... 20
    let r = USR 32768, "move 3,100, ... 20"
    let r = USR 32768, "move", a, 100, ... you get an attribute address for a specific pixel ...
    Alcoholics Anonymous Alcoholics Anonymous January 2007 Development
  • New utility - Arcade Game DesignerNo income tax, no VAT, no money back, no guarantee... In advance of SEUD's release I thought I'd release AGD to get people in the mood for game maki…

    ... back to AGD with Rand Usr 24000[/QUOTE]

    ... 't restart with the rand usr.[/QUOTE]

    Thanks, I ... BASIC with the address of this string in the BC register pair. In ... other words, LET S=USR 34100 would put the address ...
    jonathan jonathan April 2008 Development
  • New utility - Arcade Game DesignerNo income tax, no VAT, no money back, no guarantee... In advance of SEUD's release I thought I'd release AGD to get people in the mood for game maki…

    ... BASIC with the address of this string in the BC register pair. In ... other words, LET S=USR 34100 would put the address ...
    mulder mulder April 2008 Development
  • Understanding the StackSorry folks. I guess I'm going to be a pain for a little while. Hope it's ok with everyone. I'm currently studying the stack and wrote the little pr…

    ... a PRINT USR expression. But the contents of the BC register aren' ... ) in place where the BC contents should be seen. ... that's going to BC is from 2 addresses ... ahead. Maybe a simple, LD BC, (SP) will do the ... truly pointing to some invalid address I'm not sure ...
    Arjun Arjun January 2009 Development
  • Another machine code problem, sorry[CODE] OPCODE HEX ADD LD A,00 3E00 F000 PUSH AF F5 F002 LD B,05 0605 F003 LD C,06 0E06 LOOP F005 POP AF F1 ADD A,C 80 DEC B 05 …

    The way USR works is it's ... br /> When you do "USR address" it executes the machine code ... number that was in the BC register pair. So you can ... br />
    LET X = USR 61440

    Then your ... actually find the address you called in the register BC. This isn ...
    joefish joefish September 2010 Sinclair Basic
  • Where to start?..Hello, First off, sorry if this is in the wrong and sorry if the questions I'm about to ask have been asked and answered numerous time! Little back…

    ... />
    The BASIC function "USR 32768" or whatever will try ... the address you've called into the processor's 'BC' register pair ('BC' is ... the 'result' of the USR function. Usually you just want ... for example:
    LET X = USR 32768

    Whatever you ...
    joefish joefish September 2011 Development
  • Xor-shift random number generator for Z80[QUOTE=Patrik Rak;320244]Come on, people, [URL="http://www.jstatsoft.org/v08/i14/paper"]xor-shift generators[/URL] devised by Marsaglia, that's the w…

    ... Then use LET A = USR 60000 or wherever it's ... assemble it to any address you like and run ... What happens when you do USR 60000 in BASIC is ... number 60000 into the BC register and calls the routine. ... BC register at the time is returned as the result of the 'USR ...
    joefish joefish December 2011 Development
  • Xor-shift random number generator for Z80[QUOTE=Patrik Rak;320244]Come on, people, [URL="http://www.jstatsoft.org/v08/i14/paper"]xor-shift generators[/URL] devised by Marsaglia, that's the w…

    ... assemble it to any address you like and run ... What happens when you do USR 60000 in BASIC is the ... the number 60000 into the BC register and calls the routine. ... BC register at the time is returned as the result of the 'USR ... code in to any address and it will be ...
    Paddy Coleman Paddy Coleman December 2011 Development
  • Tutorial - learn machine code in 30mins[B][I]Message from the moderators[/I] - bigjon has requested that readers' attention be drawn to a better version of this tutorial, one which is easi…

    ... -running (over 32768) and memorable address in RAM
    ;initialise score ... 0 to 65355 in the BC register.
    We will write the ... value 0 into the BC register, ready to increase it by ... 0,0; "Your score was "; USR 33000
    Now RUN the ...
    buzzy buzzy September 2012 Development
  • RANDOMIZE USRI always thought that this particular basic command was not intuitive! If I understand correctly is means run the code from the memory address, is t…

    ... the code from the memory address, is this right?
    ... !?[/QUOTE]

    As USR returns a value, there must ... USR,USR.
    RANDOMIZE simply modifies the SEED system Variable to BC register ... many other ways. But the BC Register pair must been read. ...
    LCD LCD February 2013 Sinclair Basic
  • A quick newbish questionI'm reading through 'mastering machine code on your spectrum',as kindly posted by Mr bert on this forum. Correct me if I'm wrong from what i read,bu…

    ... basic command USR x (where x is an address) calls machine ... code at the address you ... bit value in the BC register pair. Because it returns ... br />
    PRINT USR x will obviously print the ... example LET a = USR x would store the return ...
    guesser guesser March 2013 Development
  • Machine code assistance please #1Dear all, Learning the ropes here, so please excuse these odd questions which may seem simplistic to you learned lot. This routine is placed at 33…

    ... USR command and jumps to the given address, the BC register indeed contains that address ... =USR 30000, then BASIC variable x will hold the value that BC register ... ZXSpin debugger at address 40000, you will notice that BC register holds $9C40 ...
    Black Hole Black Hole June 2013 Sinclair Miscellaneous
  • Full 16*16-digit BASIC multiplicationI liked Andre Adrian's 32-bit long multiplication routine so much that I decided to a decimal version. After all, 2^63 is only 9223372036854775808, a…

    ... in the listing. The USR call returns a 32-digit ... instead of BC
    pop bc ;BC=$2d2b (discard)
    pop bc ;BC=$3365< ...
    BuildResult: ;HL=decimal register address, DE=address in ANSWER area
    push ...
    Battle Bunny Battle Bunny July 2013 Sinclair Basic
  • Experimenting with turboloadersHello, My first post, having lurked here for a while. I'm a lifelong computer nerd, Spectrum fan since childhood in the eighties, and have recently…

    ... .

    Regarding the start address of the code: don't ... determine the address to USR to. The entry address is in the BC register when ...
    stephenw32768 stephenw32768 August 2013 Development
  • SE Basic IV Buffy v4.1 source (WIP)I've been doing a major refactor on the SE Basic source and I'd appreciate a code review from anyone who has time to look at it. I've almost certainl…

    ... x80_fval ; val$
    defw x80_fusrs ; usr-$
    defw x80_fread ; read-in ... ; stack routine address
    exx ; main register set
    ld bc, (stkend_h) ; breg ...
    chev chev October 2013 Development
  • Writing faster BASICIn terms of structuring BASIC programs, what are the best ways allocate variables, functions, arrays? Any tips. I remember INPUT mag had some suggest…

    ... :
    [code]IF USR 7997 AND USR 3435[/code]
    does ... delay from the BC register which will have the USR address in it at ... . The clause "IF USR 7997 AND USR 3435 THEN" takes 25 ... /> LET a=numexp1=(numexp2=(numexp3+USR address)):
    puts numexp1, numexp2 & ...
    Battle Bunny Battle Bunny January 2014 Sinclair Basic
  • Strange keyboard port reads on 48+Hi all, I don't know whether it was already discussed (I also searched forum, but there are too much of results searching "48k keyboard" so I didn't…

    ... . print usr xxxx will print the value held in BC register and not ... in basic is an address from the ld bc, + . Now depending on ... code and the value in BC will be a consistent value ...
    seedy1812 seedy1812 January 2015 Hardware
  • Strange keyboard port reads on 48+Hi all, I don't know whether it was already discussed (I also searched forum, but there are too much of results searching "48k keyboard" so I didn't…

    ... . print usr xxxx will print the value held in BC register and not ... 's zero. He wants the address of the IN A,(n ... is fired depending upon the address of the IN instruction.
    mcleod_ideafix mcleod_ideafix January 2015 Hardware
  • RANDOMIZE USR, PRINT USR etcHello just wondering why is it called RANDOMIZE UsR what does randomising have to do with it ? When calling machine code routine from adress x you ty…

    ... /> PRINT USR n calls the machine code routine at address n and ... returns the contents of BC register pair which ... a convenient way to call USR n and discard the numeric ...
    dbolli dbolli October 2016 Sinclair Basic
  • Reading Disks via ASMI'm hoping to port my Amstrad game to the spectrum (See the link in my sig for info) I will be targeting the 128 and +3 - the game will not work on …

    ... CHADD to point to an address line buffer, created by your ... "USR x" the return value is the contents of the BC register. So ...
    Alcoholics Anonymous Alcoholics Anonymous July 2017 Development
  • RFC: 64 column font codeIn BASIC, type CLEAR 49999 then import the code at 50000. Then type RANDOMIZE USR 50000. This will create a new channel and attach stream #4 to it. A…

    ... at 50000. Then type RANDOMIZE USR 50000. This will create a ... ; move hl down one address

    ld bc,$0005 ; the new ... ; move HL up one address

    ld bc,chan_4 ; could write ... HL up one address

    ld bc,$15c4 ; address of input routine ...
    chev chev January 2007 Development
<1234567…34>

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