by: flyinghamster

The one thing I lamented about the Apple II Plus (vs. the original with Integer BASIC) was that to make room for autostart, they had to rip out the mini-assembler in the Monitor ROM. That was the closest thing I ever saw to an assembly-language REPL before this. At least they were able to keep the disassembler.

9/23/2026, 1:14:53 PM

by: jottinger

The source code for this is apparently 8 years old: <a href="https://github.com/abagames/z80-repl" rel="nofollow">https://github.com/abagames/z80-repl</a><p>With that said, I love the idea.

9/23/2026, 1:08:14 PM

by: jhallenworld

You should support symbols... For example, the monitor on my 6800 / 6809 Exorciser simulator has this (the "Offset at..." is printed when it fixes forward references):<p><pre><code> ~/exorsim$ exor -d % a 1000 1000: start bra skip 1002: nop 1003: nop 1004: skip ldx #10 Offset at 1001 set to 02 1007: loop dex 1008: nop 1009: bne loop 100b: rts 100c: % sy 1007 loop 1004 skip 1000 start % u 1000 1000: 20 02 BRA $1004 1002: 01 NOP 1003: 01 NOP 1004: CE 00 0A LDX #$000A 1007: 09 DEX 1008: 01 NOP 1009: 26 FC BNE $1007 100B: 39 RTS </code></pre> What would be even better: "a" brings up a built-in mini-editor. When you exit, the code is assembled.<p><a href="https://github.com/jhallen/exorsim" rel="nofollow">https://github.com/jhallen/exorsim</a>

9/23/2026, 5:02:51 PM

by: networked

Cool idea! The REPL needs to handle whitespace after an instruction with no operands:<p><pre><code> > ld c,20h 0E 20 (7 cycles) > ld c,20h [<-- trailing space here] 0E 20 (7 cycles) > nop 00 (4 cycles) > nop [<-- trailing space here] unknown instruction: nop </code></pre> I also wish I could select from the completion list with Tab without typing more of the instruction, fish-style. I.e., you press Tab to go through completion 1, completion 2, ..., completion N, completion 1 again with Enter to confirm your pick.

9/23/2026, 12:35:22 PM

by: torutofu

the fun part is how fast you can get back into Z80 muscle memory once the repl is giving you immediate feedback

9/23/2026, 1:27:46 PM

by: j4cobgarby

Really nice! Would be fun if there were a few examples that could be loaded into memory

9/23/2026, 12:40:31 PM

by: corbinvachal

[flagged]

9/23/2026, 3:33:17 PM

by: Marbleferry815

[dead]

9/23/2026, 12:52:25 PM

by:

9/23/2026, 3:10:25 PM

Hacker News Viewer

Top 20

Z80 REPL (2018)

Comments