Links: Hardware and Software

Rock Crush 35th Anniversary Edition wouldn't be here without the support and encouragement to keep going from some of the people at these great sites! Please pay them all a visit.

Additionally below, I list what I reckon is essential ZX81 hardware for the 2020's user!

Steve.

First up is Paul Farrow's great ZX Resource Centre. This site is a real treasure trove for ZX81 users and contains so many utilities, free programs, games, Windows file converters as well as documentation for them all. Additionally he also sells his own CHROMA 81 board. I did mention it does Colour? I hope so! I can't praise this multifunction interface enough but suffice it to say the full details are on his website. Please pay it a visit . Meanwhile, I have to say I see lots of users modifiying their original hardware internally so they can get a TV picture these days. That is fine but it is altering a piece of computer history. I prefer to keep them original as much as possible. This interface plugs round the back and outputs an amazing quality SCART RGB video signal for your TV. Additonally I then run this output through a video converter to change SCART RGB into a 1080p HDMI signal. The final video output is just stunning, as you can see below.

PAUL FARROW'S ZX RESOURCE CENTRE!

The Chroma 81 interface is a multi-purpose peripheral for the ZX81. Its primary function is to allow the ZX81 to be connected to a TV via a SCART socket to produce an RGB picture that is sharp and bright.

The Chroma 81 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 modifications to the ZX81 since the Chroma 81 interface only requires access to those signals available on the expansion bus.

An exciting additional feature of the Chroma 81 interface is its ability to add colour to the ZX81 display. Two colour modes are provided, each supporting up to 15 colours. One mode provides an attributes file similar in concept to that found on the Spectrum. Use of this attributes file requires dedicated software to control it. The other mode provides a colour look up table that maps specific colours for each of the 128 different characters (64 normal and 64 inverse) that the ZX81 can display. This mode allows existing games to be colourised!


The Chroma 81 interface also provides the following facilities:

16K RAM pack.
8K RAM located between $2000-$3FFF, which allows support for user definable characters.
16K RAM pack located in the 48K-64K region of the memory map, which can be used for data storage.
Attribute colour mode (15 ink and 15 paper colours per character position).
Character code colour mode (15 ink and 15 paper colours per line of each normal and inverse character).
LOAD/SAVE sounds output through the SCART socket to the TV speaker(s).
Quicksilva Character Board emulation, which can be used with the Quicksilva games that supported the original board.
WRX hi-res graphics support for the onboard RAM.
RS232 socket, allowing connection to a variety of serial devices, such as a printer or a PC.
ZX Interface 2 style ROM cartridge socket, allowing the internal ZX81 ROM to be completely overridden.
Cursor joystick socket, with support for auto-fire joysticks.
Reset button.
Rear, full width gold plated expansion bus.
A set of configuration switches to allow each new facility to be enabled / disabled, ensuring full I/O compatibility with all existing hardware.
Onboard 5V regulator to prevent additional heat build up inside the ZX81.

The Chroma 81 interface measures 10cm by 10cm. The key items of the interface are shown labelled in the following photograph:

My own personal setup is shown below:

The conversion board above is available from Amazon. Below you can get an idea of the video output.

Next up is Charlie Robson's ZXpand board - again shown in my setup above at the very back. This is a SD Card interface for the ZX81 (amongst other things) and works perfectly with CHROMA 81. These are hard to get but batches do appear now and again on Sell My Retro (Look out for Sir Morris). A case for it like mine is also available on the site.

Next up is Rod Bell (Villordsutch) on YouTube. His entertaining ZX81 and ZX Spectrum game review videos are really inspiring and very entertaining! I always look forward to his latest video.

Julian Chappell of Software Farm Fame! What an amazing coincidence - here is a link to a great interview that Rod Bell did himself with the great man who wrote ROCKETMAN and FORTY NINER on the old '81:

I did a Software Farm Tribute Page many years ago... Ohh it's still there... I best link to it then since we are on the subject of the great Software Farm! The best ZX81 based software company back in the 80's.

The proprieter of Software Farm, I can't not mention the great man, without a link to his escape room business that he runs now can I?

Next, a shout out to the great Kevin Palser! He works hard to this day on his amazingly accurate ZX81 emulator for iOS devices. Firstly, here is an interview with Kevin where he discusses his emulator and what made him do it.

Now a link to his emulator. It includes versions of Rock Crush and Dan's Revenge built in! I enjoy conversing with Kevin on technical details and both himself and Paul Farrow are the main people who egged me on to complete my own project. Enjoy the emulator and show him some support!

I can't resist posting this link below and am excited for anyone who finds it and wasn't aware of it. Here is a great interview with John Grant - main writer of the ZX80/ZX81 ROM Chips. To this day he's still working - on the 5G tech specs etc. Brilliant man!

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