Learn Multi platform Risc-V Assembly Programming... For Open Source CPUs!
Simple Samples Series
| Lesson
S1 - Reading and Showing a Register Lets take a look at a Simple RISC-V program, which will read in a hex value from the keyboard, and show it back to the screen! |
 |
 ShowReg.asm
|
 |
Showing a register
| We've built upon the code of the previous 'Hello world' example. The start of the 'ShowRegA1' subroutine starts by showing a text label for the output. |
 |
| We need to show 8 hexadecimal characters (8 four-bit nibbles) for
our 32 bit register value. We use A3 to store the remaining bits to show, and A0 to contain the nibble we're working on. We add ASCII '0' to the value in A0, and add 7 to correct the value, if we're trying to show letters A-F. |
 |
| Once we've shown the 8 characters, we finish with a space and
return from our subroutine. |
 |
| Printing characters is performed by another ECALL. We use ECALL 11
to output a character from A0 to the console. |
 |
Reading a register
| We need to read in 8 characters. We use ECALL 12 to read in a character from the keyboard into register A0. |  |
| We need to convert this from ASCII to a hexadecimal value from
0-15 (0-F). |
 |
| We shift this nibble into our final register (A1) and repeat until we've done all 8 characters. We return once we're done. |  |
| Here are the results of our tests. |  |
 |
This is only a simple example, but you now
have the ability to read from the keyboard into a register, and
write a register back to the screen. This should allow you to 'try out' various RISC-V commands and see their results... so what are you waiting for... Get experimenting! |
| View Options |
| Default Dark |
| Simple (Hide this menu) |
| Print Mode (white background) |
| Top Menu |
| ***Main Menu*** |
| Youtube channel |
| Patreon |
| Introduction to Assembly (Basics for absolute beginners) |
| Amazon Affiliate Link |
| Forum |
| AkuSprite Editor |
| ChibiTracker |
| Dec/Bin/Hex/Oct/Ascii Table |
| Alt Tech |
| Archive.org |
| Bitchute |
| Odysee |
| Rumble |
| DailyMotion |
| Please note: I wlll upload more content to these alt platforms based on the views they bring in |
| 68000 Content |
| ***68000 Tutorial List*** |
Learn 68000 Assembly  |
| Hello World Series |
| Platform Specific Series |
| Simple Samples |
| Grime 68000 |
| 68000 Downloads |
| 68000 Cheatsheet |
| Sources.7z |
| DevTools kit |
| 68000 Platforms |
| Amiga 500 |
| Atari ST |
| Neo Geo |
| Sega Genesis / Mega Drive |
| Sinclair QL |
| X68000 (Sharp x68k) |
| 8086 Content |
| Learn 8086 Assembly |
| Platform Specific Series |
| Hello World Series |
| Simple Samples |
| 8086 Downloads |
| 8086 Cheatsheet |
| Sources.7z |
| DevTools kit |
| 8086 Platforms |
| Wonderswan |
| MsDos |
| ARM Content |
| Learn ARM Assembly |
| Learn ARM Thumb Assembly |
| Platform Specific Series |
| Hello World |
| Simple Samples |
| ARM Downloads |
| ARM Cheatsheet |
| Sources.7z |
| DevTools kit |
| ARM Platforms |
| Gameboy Advance |
| Nintendo DS |
| Risc Os |
| Risc-V Content |
| Learn Risc-V Assembly |
| Risc-V Downloads |
| Risc-V Cheatsheet |
| Sources.7z |
| DevTools kit |
| MIPS Content |
| Learn Risc-V Assembly |
| Platform Specific Series |
| Hello World |
| Simple Samples |
| MIPS Downloads |
| MIPS Cheatsheet |
| Sources.7z |
| DevTools kit |
| MIPS Platforms |
| Playstation |
| N64 |
| PDP-11 Content |
| Learn PDP-11 Assembly |
| Platform Specific Series |
| Simple Samples |
| PDP-11 Downloads |
| PDP-11 Cheatsheet |
| Sources.7z |
| DevTools kit |
| PDP-11 Platforms |
| PDP-11 |
| UKNC |
| TMS9900 Content |
| Learn TMS9900 Assembly |
| Platform Specific Series |
| Hello World |
| TMS9900 Downloads |
| TMS9900 Cheatsheet |
| Sources.7z |
| DevTools kit |
| TMS9900 Platforms |
| Ti 99 |
| 6809 Content |
| Learn 6809 Assembly |
| Learn 6309 Assembly |
| Platform Specific Series |
| Hello World Series |
| Simple Samples |
| 6809 Downloads |
| 6809/6309 Cheatsheet |
| Sources.7z |
| DevTools kit |
| 6809 Platforms |
| Dragon 32/Tandy Coco |
| Fujitsu FM7 |
| TRS-80 Coco 3 |
| Vectrex |
| 65816 Content |
| Learn 65816 Assembly |
| Hello World |
| Simple Samples |
| 65816 Downloads |
| 65816 Cheatsheet |
| Sources.7z |
| DevTools kit |
| 65816 Platforms |
| SNES |
| eZ80 Content |
| Learn eZ80 Assembly |
| Platform Specific Series |
| eZ80 Downloads |
| eZ80 Cheatsheet |
| Sources.7z |
| DevTools kit |
| eZ80 Platforms |
| Ti84 PCE |
| IBM370 Content |
| Learn IBM370 Assembly |
| Simple Samples |
| IBM370 Downloads |
| IBM370 Cheatsheet |
| Sources.7z |
| DevTools kit |
| Super-H Content |
| Learn SH2 Assembly |
| Hello World Series |
| Simple Samples |
| SH2 Downloads |
| SH2 Cheatsheet |
| Sources.7z |
| DevTools kit |
| SH2 Platforms |
| 32x |
| Saturn |
| PowerPC Content |
| Learn PowerPC Assembly |
| Hello World Series |
| Simple Samples |
| PowerPC Downloads |
| PowerPC Cheatsheet |
| Sources.7z |
| DevTools kit |
| PowerPC Platforms |
| Gamecube |
| Work in Progress |
| ChibiAndroids |
| Misc bits |
| Ruby programming |
Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!
Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!
Buy my Assembly programming book
on Amazon in Print or Kindle!
Available worldwide!
Search 'ChibiAkumas' on
your local Amazon website!
Click here for more info!