Sinclair ZX80 / ZX81 / Z88 Forums

A new year is looming on the near horizon, and so I wonder if you have any SW projects that you plan on creating or releasing in 2019? Please share, entice and inspire!

I have one recent almost finished project that only need documentation and packaging before release, very low level graphics in nature and super flickery.
The other project was started last week, involving coding directly for the ROM, using only the original 1K RAM. A graphical demonstration, just swap out the ROM-chip for visual pleasure

Well I keep searching for ideas to code in 1K, both lowres and hires.

Don’t know if I will switch back to ZX Spectrum to finally finish my ACES- project.

I'll surely be doing something in the area of ZX81 hardware this year. Haven't done so in a while, the 'itch' is getting stronger, pretty sure I can't ignore that for much longer.

For public consumption (as in: you can read about the gory details): very likely. Putting something out as ready-to-buy product: possibly, perhaps. No promises there.

And good chance I'll have a go at coding something for the Zeddy. Maybe a simple demo, a small game or utility - who knows. I still like to flex my coding skills (however limited) from time to time. But the hardware side of things is more my cup of tea...

dr beep wrote: ↑Sun Dec 23, 2018 10:41 pm Well I keep searching for ideas to code in 1K, both lowres and hires.

Don’t know if I will switch back to ZX Spectrum to finally finish my ACES- project.

Over 20 hires games this year! Never expected it would get so far or so fast.
Also LINGO in 1K with over 200 words in lowres.

I planned to do 10 in a year.
ACES-project still on hold.

Well, another year coming up:
Since I bought a Minstrel 3 I'll try to get it working at 3.6864 and 4 MHz to get 40 (or more) column graphics and a small speed bump. Requires changes to the divider, 236 or 256 instead of 207. Also a new ROM to deal with the changes in timing and number of rows.
Might also try to double the clock, including the video

I'm working on a Ring Tone Jukebox program for Bean's ZXGame. Hopefully it'll be ready early next year

Then after that I want to do something to commemorate the 40th anniversary of the ZX81 in 2021. I have a couple of ideas
Software: Take Grok's VB81 and upgrade it to C#.
Hardware: See if it is possible to use a couple of high speed PIC microcontrollers to handle most of the logic. For example a PIC to handle the NMI conditioning, another to handle either vga or tft output. Many PICs still run at 5V or are 5V tolerant. I just worry that 5V GALs are at EOL and I don't want to invest in a programmer for them.

Isn’t an EEPROM a suitable replacement for a GAL?

mrtinb wrote: ↑Mon Dec 09, 2019 7:17 am Isn’t an EEPROM a suitable replacement for a GAL?

Depends on what you are trying to do. EEPROM is non-volatile reprogrammable memory. A GAL is type of non-volatile reprogrammable logic array. GALs replaced PAL chips.

EEPROM is a modern version of EPROM. Although they are faster than EPROM. By faster, I mean the time between presenting the chip with an address and the chip producing valid data on its output pins.

GAL logic chips are much, much faster than EEPROM and can be programmed with some fairly complex logic equations. They can replace many ordinary 74xxx series logic chips and are especially useful for complex address decoding functions.

The modern replacement for GAL is CPLD. The problem with these is that manufacturers have stopped manufacturing through hole versions and 5V types.

Mark

What I hear you say is: Sometimes EEPROMs can replace GALs if the speed of the EEPROM is sufficient for the circuit. If the speed of the EEPROM is too slow, a CPLD can be used.

A memory chip like EEPROM can replace a GAL, if the GAL performs only simple logic AND/OR/NOT functions.
But a GAL can also do more complex things like timing dependent actions (has edge-triggered inputs) or can implement a state-machine (using internal latches)! Then it is not possible to replace them by memory chips ....

Siggi