Tut-Tut: Egyptomania the RC2014 Way

Sheila Dixon unwraps a spooktacular new version of Tut-Tut, the modern Retro classic, playfully bringing 'Egyptomania' to the premier home-built computer of the modern Retro era, the RC2014.Tut-Tut Level Ruby Rhod playing on the RC2014What's New is Old when Tomb RaidingWhy let the ancient microcomputers of the Pharaohs have all the fun when there are splendidly modern Z80 machines ready to embark on the Tut-Tut adventure. With the...

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ZX81 Bus Extender: The Expansion Board Solution

Adding expansion boards to the back of a ZX81 is always a slightly terrifying business, a fear compounded with each consecutive item tacked behind the little wedge.The wobbly expansion of expansions is a near unsolvable problem when using off the (distant in time and space) shelf products, however, when building our own expansions there's really no need to suffer. What's the answer to the wibbly wobbly's? Why a decently designed Bus Extender...

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Tut-Tut: Tomb Raiding on the Vic-20

A New Version of a Modern Retro ClassicGiven the resounding success of my little game of Tut-Tut on platforms such as ZX Spectrum, ZX81, Jupiter ACE, and the commendable port by Tynemouth Software's Dave Curran to the Commodore PET, it was an inevitable progression to broaden the game's horizons and introduce it to the illustrious Vic-20, the "Wonder Computer of the 1980s."New to Tut-Tut? What's this Game About?As the digging season of...

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ZXIO Interface for the ZX81: Part 5

IO Boards Comparison, Featuring Hitachi LCDsNow that we have 2 differing IO boards, why not put them in a side by side comparison. I figured a good test of the board would involve a simple communications project, such as writing out to a character based HD44780 compatible LCD screen.An HD44780 LCD panel is a character-based liquid crystal display that can display 16 characters per line and up to 2 lines of text. It is widely used in embedded...

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ZXIO Interface for the ZX81: Part 4

 ZXIO V2 Card with LED Expansion BoardPreviously I built a simple Input / Output board for the ZX81, tested it, identified some self induced errors then hinted that it may be worth changing designs completely. Way back in Part 1 I'd already come to the conclusion that I really shouldn't make this a simple project, so of course I went back and stared things again.Why Change  Now?Didn't the last design work and only really...

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ZXIO Interface for the ZX81: Part 3

Testing ZXIO Boards with a Variety of ZX81 and Minstrel Hardware OptionsWe're finally at the point where I go over the actual test ZXIO boards, test the addressing changes and learn why I mentioned in the first article that memory address 16507 is the "perfect location for an Output Board, and an interesting, possibly flawed location for an Input Board"Boards as Envisaged?After some simple initial testing I had prototype ZXIO boards produced....

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ZX81 Expansion Bus Cheat Sheet

While designing or reverse engineering external interfaces for the ZX81 it's usually advantageous to have some quick reference materials to hand. This is for me as much as anyone, may it be of some use to all.ZX81 Expansion Bus ConnectorZX81 Expansion Bus Connector, Viewed from Rear of MachinePinout Functions and Properties Summary TableA quick summary of the Signal and Functions of each Pin / Pad available on the Expansion BUS....

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ZXIO Interface for the ZX81: Part 2

 Last post I mentioned that the ZXIO add-on is memory mapped to location 16507. So this time I go over why 16507 and dig into Memory Mapping at little.Let's Talk about Memory MappingThe main problem with mapping an IO device to a memory location is that it can remove that location from the ZX81's physical memory. Meaning that you can potentially poke black holes right into a location crucial for executing your applications. Not so...

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