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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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dasm – macro assembler for 8-bit machines

Posted by jpluimers on 2026/03/04

Finding a reference to DASM while researching yesterday’s post @jpluimers on Twitter: “@b0rk @jilles_com Acids vs bases.”, it felt even more like a trip like memory lane as I had used it in the 1980s on Apple ][ and Apple //e after mainly using EDASM. Lisa and Merlin.

I am glad that it is still alive and kicking with home page at [Wayback/Archive] dasm – macro assembler for 8-bit machines and repository at [Wayback/Archive] dasm-assembler/dasm: Macro assembler with support for several 8-bit microprocessors.

Especially this history section on the home page rang a bell:

  • Matthew Dillon started dasm in 1987-1988.
  • Olaf “Rhialto” Seibert extended dasm in 1995.
  • Andrew “Dr.Boo” Davie maintained dasm in 2003-2008.
  • Peter Fröhlich maintained dasm in 2008-2015.
  • In 2019, the dasm source code and releases were moved to GitHub.

More links from this trip down memory lane:

and of course the bit in the previous blog post: [Wayback/Archive] assembly – What is the significance of $ # and % in 6502? – Stack Overflow (thanks [Wayback/Archive] tabol and [Wayback/Archive] Michael)

A

DASM allows numbers to be expressed in binary, octal, decimal, and hexadecimal.
  • Binary numbers use the % prefix (e.g. %1101).
  • Octal numbers use the 0 prefix (e.g. 015).
  • Decimal numbers use no prefix (e.g. 13).
  • Hexadecimal numbers use the $ prefix (e.g. $0D).
The # symbol is used to specify immediate addressing:
LDA 0   ; Load the byte from address 0 in memory into register A
LDA #0  ; Load the value 0 into register A
One can of course combine immediate addressing with a different numeric base, e.g.:
LDA #$FF ; Load the value $FF into register A

Queries:

–jeroen

[Wayback] Programming Like It’s 1979: 6502 Assembly language on the Apple ][ – YouTube

[Wayback/Archive] Advanced 6502 Assembly Programming for the Apple II – YouTube

This entry was posted on 2026/03/04 at 12:00 and is filed under //e, 6502 Assembly, Apple, Apple ][, Assembly Language, Development, History, Power User, Software Development. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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