drop of solder - The emulator ROMs for the computer ZX-Spectrum v1.0.

<b>drop of solder</b> - The emulator ROMs for the computer ZX-Spectrum v1.0.

AY-Track: "LAMERZ MUST DIE!"
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(C) Prusak
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              Emulator ROMs

     Computer "ZX-Spectrum".

              Version 1.0.



   This development is intended for debugging and testing of 
embedded software computer software. This scheme replaces the 
ROM on the computer RAM size of 64 KB. I computer owner Profi, 
so all signals are indicated on the basis of his scheme. 
Therefore bring transcripts of some names, ie

since the schemes of different car models, they may differ.

TRDOS - one of the two signals switch

        Pages ROM. When it is active,

        connects that half of the ROM, in which
        Torah contains the TR-DOS and start
        Boc menu Profi.
ROMCS - is active when you contact the following addresses:

        # 0000 - # 3FFF, if the ROM does not advance of the 
intended         kirovano.

ROM14 - the second signal switching pages

        Rom. Comes with a port # 7FFD.


   The emulator software controlled by the port # F7. Conflicts 
with other devices not created because the address decoding

over all 8 bits. The layout of bits is as follows:

0 - connects the RAM instead of ROM. Record in

    RAM is only possible when it plugged
    Research Institute.
1 - write lock in memory. Useful for

    full emulation of ROM.
2 - blocking relief ustroystva.Esli this

    bit is cleared, then press the reset button

    will connect back to ROM. Under the condition
    tanovlennom bit of relief could not be

    affect the status of the device. Exit

    from this state is only possible by

    software reset this bit, or

    way off. Also introduced

    for a complete emulation of ROM.
3 - Setting this bit to 1 will be connected
    chat the page RAM or ROM, in which

    contained TR-DOS, and there is something else in

    Depending on your machine. You
    Bor specifically TR-DOS or additional
    Noah page 4 is a bit far
    is the # 7FFD. Introduced to facilitate sufficient
    parameters to the page TR-DOS, as well as to ensure
    baking access to additional countries
    boundary in machines, in which it is not (Pro
    fi, GRM, radon, etc.).


   This device is intended for the use of ROM 27512. 
Unfortunately, for many reasons I can not realize your device 
with ProfPZU on Scorpio. Naturally, the very ProfPZU to work 
with him to be, but Here the replacement of all the pages can 
be done. Therefore, in the 4 page of RAM to work need to 
download older versions of Shadow monitor, work with 
conventional ROM. Second similar case is the interface 
"ZX-LPRINT". If his program is located in the separate ROM and 
not in the fourth page 27512, this ROM is also not emulated

be. When you install the emulator, ROMs, located in the 
computer, you must rearrange his platu.Shema designed to 
connect to the system bus. No additional signals are required. 


   At the moment, the emulator built and running, so the scheme 
should not contain errors. Prototype showed brilliant

results. Now you can do with
its ROM anything. For example, you can completely change the 
NMI handling routine in TR-DOS - this hitherto worthless button 
can be a truly magical! 

   Prototype testing showed
only a nuance that relates the work
TR-DOS in memory. During initialization, TR-DOS ROM connects to 
the place. This phenomenon - a consequence of the routines with

addresses of 15672, which aims to check if the Interface-1. To 
do this, it clears port # F7, hoping to get an answer

from the interface. Below is her full
Text:

15672 XOR A; zero the port # F7

      OUT (247), A

      IN A, (247); consider his condition

      CP 30; interface-1 is responsible?

      JR Z, 15,684, and if so, create it

                  ; System variables

      CP 1931

      RET NZ; if not, return
15684 RST 8; creating system variables
                  ; Variables interface-1

      DEFB # 31

      LD A, 1, is written by the command SAVE
                  ; Vat 1 copy

      LD (23791), A

      RET; Returns


   To ensure the work of TR-DOS memory
emulator must correct this routine zanesya two zeros at the 
addresses 15673 and 15674. After that, the port # F7 stops

null.

FD

          ; (If you have not read, then

          ; SORRY).