S P E C T R U M    

                       [  S O F T R O M  ]

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ROM DETAILS 
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The SOFT-ROM code supplied on the tape is an altered version 
of the Sinclair operating system and has the following changes 
incorporated :- 


 	a) The Non-Maskable Interrupt (NMI) service routine at 0066h
           has been altered to give an ESCAPE function from a crash.
           The normal error routine is used so programs which change
           the ERR-SP system variable will cause problems. 

        b) The RESET code at location 0000h will perform a NEW rather 
           than a total memory clear. BASIC programs will be lost. 

        c) Hexadecimal notation has been implemented (see separate 
        sheet for listing). 

        d) The LOAD routine at 0556h will also print to the screen
           the starting address and the length of the code block 
           after the program name. 

        e) The default colour attributes are black paper and white 
           ink.

With the SOFT-ROM loaded with "ROM" and switched to SOFT, enter 
BEEP 10,10 and while the note is sounding activate NMI. This 
demonstrates the ability to break out of an otherwise 
uninterruptable loop. 
Try using the Hexadecimal notation wherever a number can be used 
e.g. SAVE "filename" CODE &B000,&E8A 
     RANDOMIZE USR &FCOO 

Included on the tape (after, the "ROM" code) is a text file to be 
loaded into the Hisoft "GENS" assembler and has the filaname of "GENSFILE". 
This file has all the changes made to produce "ROM" listed. 


DYNAMIC RAM MEMORIES AND RESET 
On the Spectrum as supplied From Sinclair, the power on RESET is 
approximately 2OOmS long. This is far too long for the REFRESH of 
the 32K Dynamic memory to be maintained. Refresh will be 
suspended for as long as RESET is held low. Therefore if the 
CODE at location 0000h is to be changed to allow RESET to have 
other functions then a short pulse, less then 2mS must be used. 
By removing the luF capacitor ( C27 ) INSIDE the Spectrum and 
removing the small red link under the SOFT-ROM this will be 
achieved. You will then be able to use RESET without corrupting 
memory. 


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