Project PENTAGON-1024 SL

haugh All.
The original is located at http://pentagon1024.narod.ru/
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The best way to save your friends is not to betray them.
(From ZX-Format #8)
Project PENTAGON-1024 SL

Attention to all those interested in ZX-Spectrum _hardware!!!
A difficult time has come for the Spectrum. The platform exists almost on sheer enthusiasm; there are no serious developments in the field of _hardware_. However, people, oddly enough, do not lose
interest in the Spectrum (judging by what is happening on the Internet).

Modern software products in the ZX-Spectrum field,
offering more and more new features, require more and more
new resources, while mass production of _hardware_
has been completed a long time ago. The way out of this situation
suggests itself - everyone who can (and who is not too lazy)
attacks their computer with a soldering iron at the ready.
The results of such _experimental design developments_ are
very different(you can create SOMETHING unique, or you can, in a fit of uncontrollable rage after another unforeseen incident, throw everything to hell).

In order to somehow compensate for the sad situation, it was
decided to create a new Spectrum-compatible computer that would meet the requirements of most users. Immediately
it was decided to base it on a Pentagon-128
K class machine (1993), which, according to most users, is
the most original domestic development in the field
ZX-Spectrum. There are no unnecessary _bells and whistles_ (as in ATM-Turbo,
ZX-Next or Profi), there are no glitches associated with
incompatibility with the original ZX-Spectrum and brakes due to
too long INT signal, familiar to users of Scorpion
or the same ATM-Turbo.
Now intensive preparations are underway for the layout of the printed circuit board
of the computer, which is a clone of the ZX-Spectrum of the PENTAGON class.
The internal structure of the computer has already been fully thought out
(as close as possible to the PENTAGON-128K developed in 1993).
The circuit diagram at this moment (05.24.2004) is 80% ready.

Main characteristics of the computer:

- RAM capacity 1 MB. (SIMM module is used). Controlled
ports #7FFD and #1FFD. Port #1FFD bits, switching
RAM pages,the same as for machines of the KAY-1024 class.
It is possible to disable the ROM from the 0th page and
connect the 0th page of RAM instead.

In order to ensure the functionality of programs whose authors
use a lame method of switching RAM pages
(OUT #FD,A) a latch is provided on port #1FFD, similar to the
latch 48K in port #7FFD.

- The scan parameters and duration of the INT signal fully
correspond to the PENTAGON-128K.

- Kempston Joystick and Kempston Mouse devices are recognized
as standard input interfaces and are integrated on the system
board.

- A system system is provided for connecting peripheral devices (primarily the hard drive) bus, the layout of which
corresponds to the Nemo Bus developed by Nemo.
(There may be minor differences due to the very original circuit design solutions used by Nemo).
The most loaded bits of the processor address bus are buffered before
connecting to the system bus.

The drive controller is located on the system board. (Anyway,
you can’t do without it even when using a hard drive; after all
there’s nothing else to copy from to a screw for now).

As mentioned above, the circuit is 80% ready. Since I'm a student, and it's time for the session, at the time of deliverytests and
exams (i.e., for almost the entire June), work on the project will be
suspended, but after passing everything that can and should be passed,
work will continue.

ATTENTION! I am extremely interested in the opinion of Spectrumists regarding my project. If, after reading all this, there are people
READY TO ASSEMBLE this computer for themselves when the
wired printed circuit board appears, or simply people who don’t care about all this
thing, then please send feedback and
suggestions to KingOfEvil(a)yandex(dot)ru.

For those interested, I can offer the following options:

As soon as the wired board appears, I can order There are several copies to be produced, and after I have made a prototype and de-glitched everything, I will be able to provide ready-made blank printed circuit boards (at the price of the manufacturer) and the necessary firmware to everyone. (If you live in
Moscow or the region, then there will be no problems with this). The circuit and all
documentation will be published on this site by that time.

For those who want to independently order the production of
a printed circuit board, I will provide photo templates or a PCB
file with a wired board free of charge.

Anyone who is not indifferent to these lines, please
send feedback and suggestions toKingOfEvil(a)yandex(dot)ru.
I will try to answer everyone and take into account all your wishes.

Zhabin Alexey, 05/24/2004.

P.S. As the project progresses, updates will appear on this site, and soon I will publish the first version of the circuit diagram.
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ra.id

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Sent via server Forums@mail.ru - http://talk.mail.ru

haugh All.
To avoid possible misunderstandings, I inform you that I am not the author of the message, the author of the message is Alexey Zhabin, and I
only redirected this message to the conference.
It seems to me that the author of the message does not read Fidosh
conferences, so if you want to discuss this topic PERSONALLY with him,
write to KingOfEvil(a)yandex(dot)ru.

This is what was published on the site on May 27.

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Yesterday (05/26/2004) the first review was received:

Q> And now wishes. I would like the video output to be both
VGA and SCART. <-> You can also provide the ability
to connect a modem via RS-232. Perhaps this may seem unnecessary, but it’s already 2004, and many extensions have already been developed for the Spectrum. It would be a sin not to use at least
some of them. <-> Sincerely, Alexander.

A> It is very problematic to make video output on VGA due to the fact that
the Spectrum scanning parameters are focused primarily on the
TV standard (this was invented by Sir Clive Sinclair, and, in fact,
that is why the Spectrum has gained enormous popularity both with them (abroad) and with us). It's still not possible to do without modifications to VGA monitors. As practice shows (I personally checked it myself)
they connect to the Pentagon almost without modificationsEGA monitors.
They only need to output the vertical and horizontal
sync signals and the intensity (BRIGHT). In my case, all
additions came down to adjusting the horizontal synchronization with a variable
resistor on the back panel of the monitor. As for SCART, then
there are no problems at all - you just solder the connecting cord RGB
(computer) -> TV (SCART) and that’s it. Therefore, in my Pentagon - 1024
the 'video' connector will be wired as EGA, it will be possible to connect to the monitor
and via SCART to the TV.

Regarding the modem via RS-232, things are vague here (I myself have not connected the modem to
Spectrum yet). I wouldn’t want to do all this on the same
board with the computer, otherwise you’ll end up with some kind of monster
like ATM or Profi. The Nemo bus was made specifically for various peripherals. By the way, when you connect a modem to it, RS-232 is not needed. True, in such an implementation it will be necessary to either invent a new modem or modify the existing ones in some way (I don’t know if there is a human modem for the Nemo bus). I think that connecting a modem (and other peripherals)
in this way will be the most reasonable and promising.

Well, as for the many extensions, if they are well
developed, then there will be no problems with the connection - they are simply
inserted into the Nemo bus and you can use it.

By the way, some of this many extensions are already
provided for in my project - this is Kempston mouse (it will be
directly on the computer board) and, in fact, expansion of RAM up to
megabyte.