Lisp in 99 Lines of C with TinyLisp.

As one of the oldest programming languages still in common use today, and essential for the first wave of Artificial Intelligence research during the 1950s and 60s, Lisp is often the focus of interpreters that can run on very low-powered systems. Such is the case with [Robert van Engelen]’s TinyLisp, which only takes 99 lines of C code and….

https://github.com/Robert-van-Engelen/tinylisp

#tinylisp #c #programming #engineer #media #z80 #retro #tech #news

Z80:
modify address in register: inc hl
modify data pointed by register: inc (hl)
use constant: ld a, 42
read constant address: ld a, (42)

68k:
modify address in register: addq #1, a0
modify data pointed by register: addq #1, (a0)
use constant: move #42, d0
read constant address: move 42, d0

There's a good reason why 68k created that inconsistency around immediate data and absolute addresses, but it's annoying that I keep making mistakes when moving between CPUs

#Z80 #mc68000 #RetroComputing

Z80:
modify address in register: inc hl
modify data pointed by register: inc (hl)
use constant: ld a, 42
read constant address: ld a, (42)

68k:
modify address in register: addq #1, a0
modify data pointed by register: addq #1, (a0)
use constant: move #42, d0
read constant address: move 42, d0

There's a good reason why 68k created that inconsistency around immediate data and absolute addresses, but it's annoying that I keep making mistakes when moving between CPUs

#Z80 #mc68000 #RetroComputing

I've been compiling and installing the current #FUZIX sources for the #rc2014 platform yesterday and am quite impressed by the work @etchedpixels did so far.

Of course, you can also play #StarTrek on FUZIX ...

#Z80
#UNIX
#8bit

I've been compiling and installing the current #FUZIX sources for the #rc2014 platform yesterday and am quite impressed by the work @etchedpixels did so far.

Of course, you can also play #StarTrek on FUZIX ...

#Z80
#UNIX
#8bit

A proof of concept Z80 Assembly program that "[...] simulates task multitasking that can run up to eight separate tasks at the same time." It requires a specific hardware and software setup.

https://github.com/bchiha/Ready-Z80/tree/main/29-Multitasking

#z80 #multitasking #assembly

Recreating a Homebrew Game System from 1987

https://alex-j-lowry.github.io/z80tvg.html

#HackerNews #HomebrewGaming #RetroGaming #1987 #GameDev #Z80

Pre-emptive Z80 multitasking explainer

https://github.com/bchiha/Ready-Z80/tree/main/29-Multitasking

#HackerNews #Preemptive #Z80 #multitasking #explainer #Z80 #Multitasking #TechExplainer #RetroComputing #HackerNews

#scheme for the #amstradcpc anyone? #z80 #cpm

https://spectra.video/w/qvxsFMhciScC1T2py3eFvB

going live for a bit, working on the text editor that is supposed to ship with the suite of tools with the people's permacomputer model 1.

#permacomputing #retrocomputing #tinybasic #6502 #z80 #livecoding #peertube #retro #emacs #retrogames #texteditor #programming

https://spectra.video/w/qvxsFMhciScC1T2py3eFvB

going live for a bit, working on the text editor that is supposed to ship with the suite of tools with the people's permacomputer model 1.

#permacomputing #retrocomputing #tinybasic #6502 #z80 #livecoding #peertube #retro #emacs #retrogames #texteditor #programming

Keeping track of progress of the Z80 Noveau FPGA-based project. Now with sprites!

Details of the sprite logic in the Z80 Nouveau VDP finite state machine Verilog modules.
This provides an implementation of a TI9118-compatible graphic display.

@ John's Basement

https://www.youtube.com/watch?v=NmcVoH9CotA

#z80 #z80nouveau #sprites #fpga #verilog #vhdl

@raymierussell
You've done some great work handling text! You're right that and'ing and or'ing on display memory is slow.

I have a routine that renders the text offscreen, then copies the buffer to screen using the stack very fast.

Very rough and off the top of my memory:

LD SP, <screen memory>
LD HL, <offscreen buffer>
LD BC, <byte count>

LOOP:
LD DE,(HL)
PUSH DE
INC HL
INC HL
DEC BC
JP NZ, LOOP

So you only AND and OR the head and the tail of the string on screen, and only in the cases that's needed.

Another optimisation is to keep two pointers, one for each of the two characters you have to print next, each pointer pointing to the start of the character bits in the font table. So after fetching pixel bits, you only and and or between registers, and you only EX pointers, also swapping fast.

#ZXSpectrum #Speccy #Spectrum #retrocomputing #z80

Keeping track of progress of the Z80 Noveau FPGA-based project. Now with sprites!

Details of the sprite logic in the Z80 Nouveau VDP finite state machine Verilog modules.
This provides an implementation of a TI9118-compatible graphic display.

@ John's Basement

https://www.youtube.com/watch?v=NmcVoH9CotA

#z80 #z80nouveau #sprites #fpga #verilog #vhdl

@raymierussell
You've done some great work handling text! You're right that and'ing and or'ing on display memory is slow.

I have a routine that renders the text offscreen, then copies the buffer to screen using the stack very fast.

Very rough and off the top of my memory:

LD SP, <screen memory>
LD HL, <offscreen buffer>
LD BC, <byte count>

LOOP:
LD DE,(HL)
PUSH DE
INC HL
INC HL
DEC BC
JP NZ, LOOP

So you only AND and OR the head and the tail of the string on screen, and only in the cases that's needed.

Another optimisation is to keep two pointers, one for each of the two characters you have to print next, each pointer pointing to the start of the character bits in the font table. So after fetching pixel bits, you only and and or between registers, and you only EX pointers, also swapping fast.

#ZXSpectrum #Speccy #Spectrum #retrocomputing #z80

I don't have survivalist inclinations, but I entertained the thought for a moment. Consider it sci-fi.

What if all semiconductor and computer production stopped today, indefinitely?

#permacomputing #retrocomputing #ZXSpectrum #Speccy #Spectrum #z80

Great #z80/6502 asm development philosophy article I stumbled onto by accident.

Great #z80/6502 asm development philosophy article I stumbled onto by accident.

Does anyone have a favorite portable computer / device based around the 6502 microprocessor?

The #z80 was used in everything from TI graphing calculators to (in modified form) the GameBoy. Where are the 6502 portables? #retrocomputing

I have now written a #z80 machine code monitor for the #MailStation. The command set is very influenced by WozMon, but unlike #Woz I haven't managed to fit it in 256 bytes (yet...)

So now, in the strictest sense of the word, I have a #repl on this thing!

(While there was already a built-in hex editor, it was not suited to interactive use. A reboot was necessary to test changes, and it was restricted to writing dataflash, which has a limited number of write cycles.)