Coding - the procedure "conversion of addresses in the display area" and "conversion of pixel rows from the bottom up."

                C O D I N G



(C) Z-ZERO



   Perhaps, it is most painful issue for anyone who bursting 
with pride from the fact that He works at Speccy. For me, this 
topic at least the patient, after reading Wikipedia

in the ZX-PILOT'e # 34, signed VIRTUAL'a -
me (figuratively speaking) took the "anger" and
VEL has acted as the instigator ... In short,
read.


   To start touch the topic "conversion of addresses in the 
display area. 

   Entrance:

   HL - address of the upper byte of the necessary familiarity.

   Weekend:

   HL - address corresponding to the attributes.


        SRL H

        SRL H

        SRL H

        SET 4, H

        SET 6, H


   And the reverse protsedurka ...

   Entrance:

   HL - address in atribitah.

   Weekend:

   HL - address of the upper byte of the corresponding 
familiarity. 


        SLA H

        SLA H

        SLA H

        RES 7, H


   Shorter than an all-time!

   Next prog, performs conversion of pixel rows from the bottom 
up. 


        LD HL, # adr in screen

        DEC H

        LD A, H

        AND # 0F

        CP # 07

        JR Z, CONT

        CP # 0F

        RET NZ
CONT LD A, L

        SUB # 20

        LD L, A

        RET C

        LD A, H

        ADD A, # 08

        LD H, A

        RET


   Immediately say, that in the ZX-Review mentioned the 
shorter, but I have not seen or tested, and this satisfies me 
authorized. 

   Annex (VEL! They must be!!!) Hangs another of my prog (ALASM 
FORMAT), Koya designed to survey the keyboard, not

regardless of interruptions, as well as not 
deskriminiruyuschaya SCORPION'schikov. 


   Entrance:

   NISHISHA!

   Weekend:

   In the A-code key pressed.

   Comment:

   After starting the prog hangs there and waits. Interviewed 
as a simple click, so and through CapsShift 'SymbolShift, as 
well as: Break, SS + Enter, SS + Space, CS + Enter, ExtMode, 
codes Delete, Graphic, Cursor, Edit, CapLock, True Video, 
Inverse Video. In! The entire survey is performed by a table 
that can be easily changed. 


                                11/XXII-99

                       Z-Zero SYSTEMS inc.