ZXNet эхоконференция «hardware.zx»

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* Forwarded by Kirill Frolov (2:5030/946.25)
* Area : RU.PHREAKS (Unknown area)
* From : Ivanov Arthur - lead.engineer, 2:5020/400 (24 Mar 00 20:58)
* To : All
* Subj : Трактат об эмуляторах (3 from 3)
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From: "Ivanov Arthur - lead.engineer"


;SECOND GENERATION PAYPHONE CARD'S EMULATOR
;Variant 1 - optimized but incorrect a little
;Assumed that real payphone does not try
;to fuse an unit cell fused already

;Intel 87C49 (Quartz - 11 MHz)
;External power supply /battery card/
;T0 - Clk It is an example
;T1 - Reset how one can implement things
;P1.0 - Out on a really wrong platform ! /smile/

Start: mov r0,#28h-1
Units2RAM: mov a,r0 ; Units data are placed in RAM [0]..[27h]
movp3 a,@a ; At the same time [0] and [1] are being
mov @r0,a ; used as a work registers r0 and r1
djnz r0,Units2RAM ; r0 ( [0] ) is equal to 0 after djnz
Reset: orl p1,#1
mov r0,#0c0h
jt1 $
MainLoop: jt1 RstHigh
jnt0 MainLoop
Read: inc r0
mov a,r0
movp3 a,@a
jb1 StaticData
mov a,@r0 ; r0 = 0 then refers to itself
StaticData: outl p1,a
Failure: jt0 $
jmp MainLoop
RstHigh: jt0 Reset
jt1 RstHigh
jnt0 $
Write: mov a,r0
jb7 Failure ;Avoiding an emulator detection in real payphone
anl p1,#0feh
inc @r0
jt0 $
jt0 Read
jnt1 $-2
RstHigh_2: jt0 Reset
jt1 RstHigh_2
jnt0 $
WriteCarry: mov a,r0
anl a,#0f8h ; a.0 is clear
add a,#8
mov r1,a ; r1.0 is clear too
inc @r1
inc r1
inc @r1
inc r1
inc @r1
inc r1
inc @r1
inc r1
inc @r1
inc r1
inc @r1
inc r1
inc @r1
inc r1 ; and now r1.0 ( [1].0 ) is clear after 8 inc
inc @r1
jt0 $
jmp MainLoop

org 5fh

db 0dh,0ah
db 0dh,0ah
db '+---------------------------+