[zxspectrum] [SEMIOT][SPAM] - Interfaccia video color per ZX91
- From: Eugenio Ciceri <zx.eugenio@xxxxxxxxx>
- To: zxspectrum@xxxxxxxxxxxxx
- Date: Wed, 22 Oct 2014 00:58:32 +0200
Qualcuno la conosce già?
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Hello
I’m pleased to announce the launch of the Chroma 81 interface, a new
multi-purpose interface for the ZX81. Its primary function is to allow the
ZX81 to be connected to a TV via a SCART socket using an RGB connection to
produce a picture that is sharp and bright. The Chroma interface plugs into
the expansion port of the ZX81 and connects to the TV using a standard
SCART cable. There is no need to make any modifications to the ZX81 since
the Chroma interface only requires access to those signals available on the
expansion bus.
An exciting feature of the Chroma interface is its ability to add colour to
the ZX81's display, with support for a palette of 15 colours and 2 colour
modes. One mode provides an attributes file similar in concept to that of
the Spectrum, giving maximum flexibility in creating a colour display but
can only be used by new software developed to explicitly control it. The
other mode allows colours to be assigned for each character in the
character set, and then whenever a character is displayed it will be shown
in its defined colours. The colour mappings are retained across a LOAD and
so it is possible to load a game and for it to be displayed using the
defined colours, i.e. existing games can be colourised!
But the features of the Chroma interface don’t end there, as it also
provides the following:
- An onboard 16K RAM pack.
- Additional 16K RAM that be mapped into the 48K-64K region, or the 8K-16K
region.
- Support for a user definable character set within the RAM located in the
8K-16K region.
- Support for WRX graphics format, allowing true high resolution graphics.
- QS Character Board emulation, allowing a user definable character set and
operating with the range of Quicksilva games that supported the original
character board.
- A ROM cartridge socket that allows complete overriding of the ZX81 ROM,
making it possible to run replacement operating systems or ROM
enhancements, e.g. the Skywave FORTH ROM, the ComprocsysASZMIC ROM, the
dk'tronics and Kayde Graphics ROMs. The socket is compatible with my range
of ZXC ROM cartridges, including the recently released ZXC4 that contains a
4MB FLASH ROM (opening the potential to store 100s of games on a single
cartridge for instant loading).
- A Cursor joystick socket, with support for auto-fire joysticks.
- An RS232 socket, which could be useful for connecting to a printer, modem
or a PC (a ROM cartridge program is already available to allow loading and
saving via RS232 from a PC).
- Output of LOAD/SAVE sounds through the TV speaker(s).
- A set of configuration switches to allow each facility to be enabled /
disabled, ensuring maximum compatibility with all existing hardware, e.g.
ZXpand.
- A full width, gold plated rear expansion bus.
- A reset button.
The Chroma interface is constructed from a professionally made board that
measures only 10cm by 10cm. You can see a photo of the interface and read
further details about the facilities it offers at:
www.fruitcake.plus.com/Sinclair/ZX81/Chroma/ChromaInterface.htm
There are a few points worth being aware of before ordering:
- The interface only outputs a picture in RGB format (not composite video
or S-video).
- The interface has only been tested with 50Hz models of the ZX81, i.e. UK
and Europe. In theory it will work with NTSC versions but this has not been
proven.
- The interface has not been tested with any clones of the ZX81 and must
therefore be assumed to be incompatible with them.
- It is strongly recommended to use the 1.2A version of the ZX81 power
supply. The original 0.7A version might not be sufficient if other devices
or a ROM cartridge are to be used. If more current is drawn than the power
supply can safely handle then it could overheat and pose a fire risk.
- The SCART output accurately reflects the picture available from the RF
output. Slight shimmering or bending of the top row of the picture will be
visible if it occurs in the original RF output.
- Flat screen TVs made by Panasonic do not appear to implement the SCART
specification correctly and can result in the Chroma picture being shifted
to the left or at worst being unstable and continually jumping
horizontally. There may be other TV models that also do not display the
picture from the Chroma interface correctly, but most makes appear to work
ok.
- The interface is fully compatible with the ZXpand SD card interface.
- Flicker-free games originally developed for use with the ZX80 fitted with
the 8K ROM upgrade may not display a perfectly stable picture due to
inaccurate timings in the games. A TV tends to be far less tolerant of
frame timing variations in a SCART signal than it is in an RF signal.
- A SCART cable is not included. Almost all commercially available RGB
SCART cable will be suitable, allowing you to select your preferred length.
- A RS232 cable is not included. If your PC does not have a built-in serial
port then a USB-RS232 adapter can be used. A standard 9-way non-crossover
serial cable is suitable for use with the RS232 socket, and can be used to
connect to a serial printer or a PC (although note that custom software
must be created to control the RS232 port).
- The ROM cartridge socket supports my ZXC4 ROM cartridge, which contains a
4MB FLASH ROM. The ZX Cartridge Creator utility (for Windows) can be used
to program a single ZX81 ROM file only into a ZXC4 ROM cartridge using a
Spectrum. It will soon also support the ZXC3 ROM cartridge. In the future,
I will be enhancing the Cartridge Creator software to allow multi-program
compilations (.ROM and .P files) to be constructed and downloaded to ZX81
using RS232, and then the ZX81 will program the data directly into the ZXC3
or ZXC4 ROM cartridge.
- The Chroma interface is uncased (I hope to be able to offer a custom case
in the future if economically viable).
- The main logic IC and onboard 5V converter do get hot in use but this is
expected behaviour.
- Modern TVs tend to struggle to display the RF output from a ZX81.
However, it is usually possible to obtain enough of a picture to prove that
the ZX81 is operational. You should only connect the Chroma interface to a
ZX81 that you are confident is in working order else damage may occur to
the Chroma interface.
The cost of the interface is as follows:
- Chroma interface = 60.00 GBP
- Postage and packaging (Signed For / Tracked delivery):
- Within UK = 4.75 GBP
- Within Europe = 9.75 GBP
- Outside Europe = 11.15 GBP
The easiest payment method is PayPal and my account is
rainbow@xxxxxxxxxxxxxxxxxx
I am able to provide ZXC4 ROM cartridges, which can be used with either the
ZX81 or the Spectrum. Please email me if you would like price details. Full
details of the ZXC4 can be found on my website.
Regards
Paul Farrow
www.fruitcake.plus.com
www.zxresourcecentre.co.uk
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E qui c'è anche un'interfaccia per lo Speccy che permette risoluzioni
colore più alte:
http://www.fruitcake.plus.com/Sinclair/Spectrum/Spectra/SpectraInterface.htm
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