GMX-info

Due to numerous requests from workers, we present
a brief description of the GMX board (with the kind permission of Zonov S.Yu.).

GMX (Grafic_Memory_eXtension device for Scorpion 256)

>1.Memory expansion up to 2MB.
Among the various, both existing and possible options
organization, the choice fell on the option that was implemented in Profi.
That is, it is done in such a way that simply 256Kb are addressed the same way as it was,
through the usual Scorpio standard, and everything that is higher is according to
the Profi standard - port 0DFFDh. Since Profi has a maximum memory of 1MB, you can work with all memory from 0 to 1MB according to the Profi standard. It’s just that physically these will be different memory pages.
For example, you can download some program for Profi
that uses memory up to 1 MB and at the same time painlessly use
Shadow Service Monitor.
Gradations for memory expansion:
256Kb, 512Kb, 1Mb, 1256Kb, 2Mb - standard Simm modules. Moreover, you can
install from one module with a capacity of 256Kb (you get Scorpio memory)
to 2 modules of 1MB each - the total memory will be 2MB.

>2. Graphic screen 640*200(208) and plus a hardware scroller.
The number of colors is the same as in the regular ZX Spectrum. For each byte of graphics
- one byte of attributes. In order for the image to be in color, it is necessary
mandatorythe presence of 2 Simms, i.e. at least 512Kb. Addressing
of the graphic screen starts at 4000h, and is completely linear,
i.e. the first 80 bytes are the first line of the screen, the next 80
bytes are the next, etc. Screen attributes are stored in one of the
extended memory pages. Their addressing is exactly the same. The main
purpose of advanced graphics is a standard text screen of 80 * 25
characters (a character has a size of 8 by 8 pixels), necessary for
working with text editors and email programs.
To speed up work in text mode, hardware
scrolling up and down is used.
In the future, due to the possibility of changing the scheme by changing
the ROM firmware, it will be possible to introduce additional graphic modes.

During While discussing the graphics capabilities of the GMX board with potential
users, we received a lot of advice and recommendations about
what needs to be added to the circuit. In first place was
the additional graphics mode 320*200 - each dot has its own color.
We are currently working on creating such a mode, and I repeat
once again that this will only lead to a change in the ROM. In addition
if it works out, we plan to do something like a simple
blitter: hardware transfer of one memory area to another,
filling a memory area with a given byte, etc.

>3. ProfessionalROM040 (512Kb).
It is planned to remake the Shadow Monitor to work in 640*200 mode,
Russify it, further expand the built-in service
capabilities of the shadow monitor, primarily aimed at improving
work with HDD, support for various operating systems, and also
support for the ability to work with HAYEs-compatible modems.
In addition, the ROM, as already mentioned the GMX board schematic is also stored.
Moreover, it is made so that from the TM it will be possible to radically change the circuit,
loading one of several possible options.
As for Professional ROMs for regular boards, they will
be changed only if any errors are detected in their operation
or the added capabilities fit into the existing hardware
limitations. Today, version number 4.1 is being released.
The most important and basic advantage of the EPROM installed on the GMX
board will be the ability to reprogram it by the user. First of all
this applies to programs recorded on a ROM disk. The user will be able
to select programs to suit his taste, create the contents of his ROM
disk himself, and also update the version of the Prof ROM on site. This
is achieved by using modern flash memory chips
as ROM.

>4.Increasing compatibility with the ZX Spectrum and Pentagon.
To do this, enter the shadow monitor menuadditional
menu bar Standard Spectrum. In this case, all
additional ports are disabled and at the same time the standard
ROM of the ZX Spectrum 128 & TRDOS is turned on.
In addition, the ability to set temporary parameters has been introduced
Pentagon-128 and Profi.
When switching to these modes, the computer turns into an absolutely
standard ZX Spectrum or a Pentagon (you can easily do and
Pentagon-512) or Profi, while completely “forgets” about his
additional capabilities. Exiting this mode, of course, is only
by pressing the reset button.
The standard Pentagon mode, as well as the Pentagon-128, provides
first of all, full compatibility with Pentagon-class computers in terms of
timing diagrams of television scan counters, duration and
position of the INT signal, and the absence of the Wait signal. This will allow
some demo programs to work as they would work on
Pentagone.

>5.Turbo with an acceleration factor of 1.8-1.9.
Switching Turbo/Normal as now: both software and hardware.
Upon user request, versions with a clock frequency
of 14 MHz will be supplied.

>6. Design.
This is a board measuring about 80*110 mm, inserted into the socket
for the Z80 on any Scorpio model.
In addition, a cable (included
in the delivery kit) is soldered to 10 points of the old board, throughwhich the following signals are supplied/removed to the GMX board via a 10-pin
connector: R, G, B, Sync, Magic,
RDR/-reading ROM, CSR/- accessing RAM, +5v, Ground.

>7.Economic indicators.
Estimated cost of a GMX board with RAM
512Kb - $35 - 40 (Price manufacturer.)

>8. Dates for the start of mass production and sales.
Today, the GMX board is at the stage of printed circuit board
layout, so we hope that mass production and sales
will begin towards the end of autumn 1997.

>9. Using GMX on other Spectrum-compatible computers.
We plan to include all the information on how to upgrade another computer
to support GMX along with the GMX documentation. In fact, any
Spectrum-compatible computer when using the GMX board requires:
support for a music coprocessor, support for a TRDOS controller,
support for a keyboard port, tape recorder, joystick, printer and
some minor little things.
**************************
For more detailed information, send a request to:
199048 St. Petersburg, PO Box 083 Sergei Yurievich Zonov
or by phone:
(812)-298-0653, 172-3117 (order department, from 10 to 14),251-1262
(service center, from 10 to 19) or
by email: FidoNet 2:5030/529.16, E-mail
sc...@spb.tsi.ru.
About all the shortcomings of the built-in software, as well as
about what features you would like to see in it, and in principle on
a computer, you can report by phone (812)-130-1995, or better yet by
email FidoNet 2:5030/25.1, E-mail m...@deeds.spb.ru

P.S. Will be published in full in ZX-Format N7.

Bye... bye bye, Sersh!