New - ZX-NEXT offers open architecture

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        ║ ZX-NEXT OFFERS ║█
        ║ OPEN ARCHITECTURE ║█
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   When working with almost any
Spectrum-compatible PC users up to
still experience a lot of restrictions and
inconvenience. Many of them are related to insufficient
high quality software
niya, but most of the problems are still related
tends to make incorrect decisions in the apparatus
no part.  And if the software level
provision has grown over time, then
most modern PC models are level-
The HARDWARE line remains unchanged. In this
sense, developed by SLOT (Moscow)
based on the Z80 microprocessor, the new eight-
bit microcomputer "ZX-NEXT" has
a number of new interesting solutions in circuit design
nick and design that facilitates operation
tation and eliminating deficiencies,
typical for PCs of this class.
   There is no doubt that the greatest advantage
Society ZX-NEXT is an open system
tire made in the form of a standard
62-pin XT slot (designed in-
then you can use domestic ones
connectors type SPN-64). Possibility of installing
New peripheral devices to choose from
user makes the PC attractive
for a wide range of consumers. It's so-
It also facilitates independent creativity.
   We draw your attention to the fact that everyone
involved in the development of PC devices
ZX-NEXT, full technical support is provided
what documentation. To get acquainted with the possibilities
possibilities for expanding the architecture, bringing
Here is a brief description of the system bus and non-
which technical characteristics.
   So, on the motherboard there is
possibility of installing 4 system sizes
meals  If one of the controllers (like
rule TR-DOS or 128K) docked with
it, then it is possible to install another
system connector. Thus, maxi-
small number of controllers simultaneously
connected to a PC, cannot exceed
six.
   The word "controller" means -
This board is installed in one of the system
dark connectors and containing, as a rule,
Well, several additional devices.
For example, the so-called controller
"TURBO", combines four additional
Portable devices: parallel port
(CENTRONICS), CGA adapter, non-volatile
Simulated real time clock and device
turbocharged up to 7 MHz.  In general, according to
to the quality and diversity of peripherals, ZX-NEXT
can already be considered a leader in its
family
   In order to maintain the most shi-
rocky spectr controllers, system bus
contains almost all the necessary sig-
cash.  To address devices and work with
them, the data buses are completely removed, ad-
Res and control Z80. Not displayed only
HALT signal (pin 18 Z80), because he doesn't have
There is no wide practical application.
Signals BUSRQ - bus request and BUSACK -
Bus idle confirmation allows
perform direct memory access
(DMA).  This is necessary when working fast
devices: high speed controller
local network, intelligent
HARD DRIVE controller, etc.
   To clock additional
devices, frequencies 7 and
1.75 MHz.    These signals are used
controllers 128K and TURBO. When using
When changing CGA video modes, in ZX-NEXT you can change
There is a sequence of searching addresses
in RAM to ensure full compatibility
tee with a standard ZX-Spectrum. To drain-
Execute control to the system bus
some video addresses and some
video output control signals. Withdrawn
also all video signals, which allowed
place the PAL or SECAM encoder on an additional
thread controllers.
   All devices are powered
via the system bus, which maximizes
grows their connection. Availability of some
additional signals expands the possibilities
ness of the PC. So memory control signals
allow the use of bootable RAM
(instead of ROM), expand BIOS functions (with
connection INTERFACE 1) and do not
which are additional functions. I see,
that the ZX-NEXT system bus allows
connect almost all types of add-on
devices designed for
Spectrum-compatible PCs. Therefore, I propose
solution required in this PC, you can
be considered as an attempt to introduce
necessary for users and developers
cam standard for the system bus for
computers of this class.
   Will SLOT be able to convince many
numerical developers and manufacturers
ZX in the need for such standardization -
time will tell, but they all must agree
it seems that without uniting common efforts,
it will not be easy for our good ZX to survive in
these are turbulent times.


  PC system bus pinout "ZX-NEXT"
 ───────────────────────────────────────

 1 - GND (ground)
 2 - UCC (power supply +5V)
 3 - A14 ROM (in particular used
controller 128K for SEL BASIC 128/48)
 4 - A12 CPU
 5 - A13 CPU
 6 - A7 CPU
 7 - A8 CPU
 8 - A6 CPU
 9 - A9 CPU
10 - A5 CPU
11 - A11 CPU
12 - A4 CPU
13 - SEL ROM1 (ROM DOS/SOS switching)
14 - SEL ROMO (lock system ROM)
15 - A3 CPU
16 - A10 CPU
17 - A2 CPU
18 - RAM/ROM (in particular used
to connect bootable RAM to the VMthere
ROM)
19 - A1 CPU
20 - D7 CPU
21 - A0 CPU
22 - D6 CPU
23 - D0 CPU
24 - D5 CPU
25 - D1 CPU
26 - D6 CPU
27 - D2 CPU
28 - D3 CPU
29 - RESET CPU (system reset)
30 - A14 MS (address used in private
sity for RAM segmentation with C000h)
31 - BUSRQ CPU
32 - NMI CPU
33 - WAIT CPU
34 - A14 CPU
35 - BUSACK CPU
36 - MREQ CPU
37 - WR CPU
38 - IORQ CPU
39 - RD CPU
40 - A15 CPU
41 - M1 CPU
42 - RFSH CPU
43 - A15MS (address used in particular
ty for RAM segmentation with C000h)
44 - C (data shift signal in output
video register used in CGA)
45 - Q3 (frequency 1.75 MHz)
46 - Q1 (frequency 7 MHz)
47 - AM8 (RAM control signal more
64K)
48 - CLK (processor clock speed)
49 - Q4 (frequency 875KHz; in CGA mode "1")
50 - PE (data recording signal to output
video recorder)
51 - BORD (video signal "border")
52 - C6 (video address)
53 - C7 (video address)
54 - C8 (video address)
55 - C16 (video address)
56 - BLANK (blanking)
57 - Y
58 - BLUE
59 - GREEN
60 - RED
61 - SYNH
62 - +12V

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   K. Sviridov Slot Co., Ltd, 1994
              kiSSSoft 1995
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