Забытый мультиколор (часть 4)
Полное руководство по аппаратному мультиколору для тех, кто не знает, что это такое и зачем он нужен. Преимущества и недостатки, прототип игры, перспективы
https://habr.com/ru/articles/1046992/
#zx_spectrum #zx_evolution #timex #multicolor #графика #история_it #демосцена #видеоигры #z80 #assembler
AUX0009: Assembling the RC2014 ESP8266 Wifi Module
Starquake
Blast from the past this one … and in some senses, a few months too late!
I stumbled across a spectrum emulator for the ipad (can’t remember how now …) and that let me to the World of Spectrum. Whilst knowing about Spectrum emulators (I had a paid for copy of one courtesy of, was it Brian somebody? I think I still have it on a floppy disk somewhere from around 10-12 years ago!) I haven’t touched one for a very long time.
Like many, I had a Spectrum in the 80s – the Spectrum+ was my first one, followed by a Spectrum 128 at some point. I followed all the typical titles from Ultimate (Play the Game), Melbourne House, Quicksilva and the like … and whilst there are so many I could mention, for some reason one that always stuck out in my mind and that I really wanted another go on was Starquake.
Don’t really know why, other than I remember when Crash magazine published the map of the game as a centre page I spent quite a long time exploring, using the teleports and basically working on it until I had actually completed it. Back in the time when maps were hand drawn and submitted to the magazines!
I wondered about getting the iPad emulator and having another go, but looking at all the instructions of how to get custom games onto an iPad, I didn’t get further than just downloading it .. but then I noticed a Java icon and sure enough, if you feel so inclined you can run games from World of Spectrum directly in your browser – so I had a few moments nostalgia running Starquake once again.
From the opening (always tinny, this being simple Spectrum sounds) jingle, through the in-game sounds and graphics and scarily, I actually remember a lot of how to play it and actually what you need to do at specific points – where you need to ride a platform here, but get off just there to go through this passage and collect this whatsit over here …
I wonder how much of my memory is taken up with trivial paths through games from that era … only to be reawakened via a Java emulator some 30 odd years later …
Its very interesting to note how those simple graphics often hid a simple, but very addictive gameplay. Something that gets forgotten a little with some of the large franchise titles these days, but something we perhaps are seeing a bit of a return to with some of the addictive mobile and social games.
Curiously, I still have my Spectrum 128 in the loft (along with my Atari 2600) … but I would be absolutely amazed if any of those tapes (assuming I still have a few) play any more.
But that will do for now, I have to go and find Sabre Wulf (with its colourful fauna and orchids), On the Run (more colourful fauna and very distinctive sound effects and puffy graphics), Atic Atac (‘ware the ghosts, find the keys and watch that bizarre roast chicken drain down!) and a few other real classics from the time and re-live this electronic part of my teens.
Kevin.
#aticAtac #onTheRun #sabreWulf #spectrum #starquake #ultimate #worldOfSpectrum #z80
Major milestone: my hand-wired Z80 computer just executed its first code from ROM. Verified with an led array after bringing up the ROM, RAM, and address decoder.
The first heartbeat of the Zenadi Codex.
#Z80 #HomebrewComputer #RetroComputing #Electronics #DIYComputer
Hi, I am Zaiphirion. I am building a computer from scratch. This is the beginnings of a prototype called the Zenadi Development System. It uses dual Z-80 processors. It's still a work in progress.
#RetroComputing #HomebrewComputer #Z80 #Electronics #DigitalLogic #ComputerEngineering
RC2014 Z80 NOP Tester
I’ve already talked about my Z80 CPU Tester (Fail) and how I ended up building one from existing designs. This is actually running code from a ROM and using those instructions to figure out what kind of Z80 is in use.
There is a much simpler, more basic “does it even work” test that can be done – the NOP test. At the most minimal, this is pulling the appropriate INPUT Z80 bus control lines HIGH (so not active), and all the data lines LOW. Then when power is applied, as the Z80 reads instructions off the address bus it will always read back the instruction corresponding to 0x00 which is a NOP (“no operation”) and then move onto the next instruction. As the data lines are all fixed to the same value, this too will be a NOP and so on through the entire 16-bit address space (if you wait long enough). All this really needs to work is power and a clock.
There are a number of designs published, from simple breadboard circuits, to stripboard, to bespoke PCBs, to off-the-shelf kits to buy. Searching for “minimal Z80 configuration” will find a number of them. I already have this one, which is easy to build, very simple to use, and works really well: https://lectronz.com/products/z80-nop-tester.
But given my messing about with Watching a Z80 from an RP2350 I thought it would be really useful to have one in a RC2014 bus form factor, so I put one together. Not for use with other RC2014 modules, but more for use whilst I’m prototyping RC2014 related modules myself.
https://makertube.net/w/pQNYpWJTcpsKVj5LBc5qmN
The Circuit
The tester I have has been published online by the designer, Alberto Gonzalez, and as I know how it is working, I’ve essentially ported that circuit over to the RC2014 bus.
The original design supports the following:
I’ve made the following changes:
Why the last option? Well there are some other single byte Z80 instructions that will give different patterns on the address lines as they function, so I thought that might be interesting to play with. Any instruction that is followed by a data read would work, but of course the data value will be fixed to the same value as the instruction byte.
I’m using the same 555 clock circuit as my bought tester.
The PCB Design
All the LEDs have been given a 3mm rectangular footprint and placed at the top of the board. I’m using 8-way resistor networks for all the LEDs and data line PULLs.
There is an option to power the board directly via two header pins, and jumpers for /INT, CLOCK and all the data lines.
The CLOCK control is using a trim pot, and the RESET button is a simple two-pin tactile switch.
There is a 100nF capacitor for the Z80, but I’ve stuck it under the footprint of the 40 pin DIP chip. It can be fitted on either side of the board, although the silkscreen is on the rear.
All LED bus signals are labelled.
I’ve opted not to include the additional header footprint of the RC2014 extended bus.
Note: Like many RC2014 PCBs this is a 100mm long board, which means it can’t quite get all 40 pins of the RC2014 bus to fit in. The board does not include a connection for pin 40 (USER4).
One new KiCAD-ish for me – in order to stop VCC being renamed from being connected to the Nets for the signals being pulled up, I had to use a net tie. Then I needed a custom footprint to match the 0.25mm track width I was using.
The PCB Build
Bill of Materials:
The build should be relatively straight forward. This is the suggested order:
I recommend using a 40-way right-angled pin header for the RC2014 bus, but just leave pin 40 over hanging the board. Pin 1 is marked on the board.
Usage Notes and Errata
Usage is fairly straight forward:
This is not designed to be used with other boards plugged in. It makes little sense anyway, as the Z80 can’t do anything other than read a fixed, single-byte data instruction word and a possible follow-up data word of the same value.
I’m not quite sure how I managed it, but there is a small indent in the PCB edge next to pin 1 of the RC2014 bus. It doesn’t seem to affect things however.
With hindsight, I’d probably allow for enough space to fit a 40 pin ZIF socket. One might just fit, but I think the 555 is probably too close.
Conclusion
Really this is mostly a RC2014 toy – I can’t imagine it being a lot of use for most people. But for me, for testing the monitoring of the Z80 bus in a very simple way and to help understand how the signals work, this seems to work really well.
A massive thank you to Alberto Gonzalez for publishing their design. Do go and get one if you’re interested in this kind of thing (I have no links or affiliations – I just bought one and liked it and used it as my inspiration here).
Kevin
#pcb #rc2014 #z80
RC2014 Z80 NOP Tester
AUX0008: Assembling the RC2014 Dual Serial Module SIO/2
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