┌─────────────────────────────┐
│ │
│ ELIMINATING INCOMPATIBILITIES │
│ │
│ COMPUTER "ROBIK" │
│ │
└─────────────────────────────┘
Doesn't work on computers like "Robik"
some games, which causes their authorities
businessmen feel the “deficiency” of this is very
not a bad device. This happens after
mu that these games tune the processor to
special IM2 interrupt mode, recording when
this in register I numbers #39, #3A or #3B.
In a "branded" ROM from 1982 from the address
#3900 to #3BFF are #FF bytes. Poe-
Therefore, for any low byte read,
processor in IM2 mode at each interruption
will go to address #FFFF.
Usually in these games the
take off #18. And since the address is #FFFF
follows address #0000, where it is located in ROM
code #F3, then you get a two-byte code
Manda JR #FFF4. with this approach it is economical
257 bytes are stored in memory because
every programmer strives to
his program in IM2 mode worked on
any computer with any readable by-
vol. For this purpose it is a memory section from #XX00
up to #XXFF+1 is filled with the same byte,
for example, #FD. Then the processing program
interrupts will work from address #FDFD
at any low byte read. Although
the standard for "ZX-Spectrum" is
read byte #FF, what is the data bus for?
through resistors it is “pulled up” to +5V.
Now a little about the operation of the circuit.
D1.1 D1.3
____ 1┌───┐ 10┌───┐ D4.1
IORQ (20) ───────┤ 1 │3 ┌──┤ │ 1┌─┬────┐ D1.4
2│ ├──┘ 9│ ├─────oR│T _ │6 13┌───┐
┌──┤ │ ┌─┤ │ 2│ │ Q o────┤ 1 │11
__ │ └───┘ │ └───┘ ┌─┤D│ │ 12│ ├───┐
M1 (27) ────┤ D2.1 │ │3│ │ │ ┌─┤ │ │
│ 1┌───┐ │ ├─┤C│ │ │ └───┘ │
└──┤ 1 │3 │ │4│ │ │ ─┴────X────┴─ 20 pin.
____ 2│ ├───┼─────────┼─oS│ │ cut ROM
MREQ (19) ───────┤ │ │ │ └─┴────┘
└───┘ └─────────┼─────────────────────┐
D2.2 │ │
4┌───┐ D2.3 │ 1k │
A15 (5) ───────┤ 1 │6 10┌───┐ │ ┌─────┐+5B│
5│ ├─────┤ 1 │ └────────┬──┤ ├─ │
A14 (4) ───────┤ │ │ │8 │ └─────┘ │
└───┘ 9│ ├──┐ D2.4 │ D4.2 │
A10 (40) ─────────────────┤ │ │13┌───┐ │13┌─┬────┐ │
1┌───┐D3.1 └───┘ └──┤ 1 │11├──oR│T │ │
A13 (3) ───────┤ & │ │ ├┐ │12│ │ Q├──┤
2│ │12 12│ │└─┼──┤D│ │ │
A12 (2) ───────┤ o───────────────┤ │ │11│ │ │ │
13│ │ └───┘ ┌┼──┤C│ │ │
A11 (1) ───────┤ │ ││10│ │ │ │
└───┘ │└──oS│ │ │
D3.2 │ └─┴────┘ │
D1.2 3┌───┐│ │
____ 4┌───┐ ┌─┤ & │ │ ┌┴┐
RFSH (28) ───────┤ 1 │6 │4│ │ │ 680│ │
____ 5│ ├──*─┤ o────────────┘ │ │
MREQ (19) ───────┤ │ │5│ │ │ │
└───┘ └─┤ │ └┬┘
└───┘ │
to LED│
D1,D2 - К555ЛЛ1 D3 - К555ЛА4 D4 - К555ТМ2
On elements D1.2, D2.2, D2.3, D3.1,
D3.2 and D4.2 assembled hardware diagram ana-
read the contents of the register I. If the contents
This register is in the range of
not #38 - #3B, то это смедина, что в монет
interrupts occur at an address transition
#FFFF. And how to achieve this when employing
ненной area ROM not #FF, but symbolic
naborom, for example, how in "Robique"? Very much
simple: unlock the ROM at the time of reading
the vector passes and, then, immediately ego
turn on. And so how the data bus "pulled"
to +5V through resistors, then we and semi-
as needed #FFFF even when filled-
nom section PZU.
Before proceeding with the modification,
remember that a computer is quite complex
it's a machine that you can easily bring out
I build with inept interference in a scheme and
not easy to repair afterwards. So no
take it for revision if you do not possess
have sufficient experience working with micropro-
cessor systems, please contact for
help to a more experienced person.
Now a little about the makeover itself. U
microcircuit D1 - D4 bend to the side
all conclusions except questions 7 and 14
and they are installed over any 14-
water microcircuits 555 series on the board
the computer. Outputs 7 and 14 are additional
microcircuit must be soldered to an analog
ным выдовам нижних microscheme, отгутние
выводы shorten side cutters to 3-4 mm.
Installation is carried out with a thin wire MGTF. Mick-
circuit diagram D1.4 is included in the wire break,
iduschego k 20-ym vyvodam microscheme PZU (c
"Robique" is D42 and D43). On the left of the diagram c
I have indicated the number of output processors in brackets
Z80 to which these need to be soldered
conclusions. If desired, in the scheme it is possible to establish
screw the LED ("minus" to the resistor, a
"plus" to +5B) and bring it to the front
panel. If the LED on startup ca-
кой-нибудь игры gorit, it ehthat means that
this game on an unmodified computer is not
works and the proposed
scheme.
Let us give just a small example
a list of such programs and the specified co-
contents of register I:
TOMAHAWK - #39
ROBIN - #39
SUPER 3.5 - #3B
RAMBO - #3A
3D-LABYRINT - #39
ENTERPRI - #3A
IMPACT - #39
BOMB JACK - #39
SIGMA-7 - #3B
GRYZOR 1 - #3B
CYCLONE - #3A
COMET - #39
PLANET PATROL - #39
ATARI POSITION - #3A
SURV. - #39
MIKIE - #39
SMURF 1 - #39
GRUZOR 2 - #3B
SPITFIRE - #3B
TYPHOON - #39
WEC LE MANS - #3B
SABOTEUR 2 - #3B
ZERO MUSIC - #3B
GRUZOR 3 - #3B
JUNGLE WARRIOR - #3B
MATCH DAY 2 - #3B
LOGO - #3B
PINBALL POWER - #3B
*****************************************
Alexander Nesvoval, Kharkov
kiSSSoft - 1995
*****************************************
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