Z8ASM

Z8ASM is, as the name suggests, a (simple) assembler for the Zilog Z8 processor.

The main class is Main. It accepts the .asm file as input and writes the compiled binary file to output.bin.

Syntax

.data <hex2|hex4|char|string>+ writes the specified bytes or characters directly to the memory.

.org <hex4> set the output location (only possible once).

.repeat <number> start a block which is repeated times, .end it.

where

• hex2: a 2-digit hex value, e.g. %0d
• hex4: a 4-digit hex value, e.g. %ABCD (= %AB %CD)
• char: a char converted to US-ASCII, e.g. '?' (= %2F)
• string: a series of characters (US-ASCII), e.g. "12" (= %31 %32)

Comments

Line comments start with a semicolon ; or with C-like double slashes //. Block comments are also C-like: they start with /* and end with the next */ (they can't be nested).

Labels

Z8ASM supports global labels and local labels. Global labels must not start with a dot (.) and are available globally.

Local labels start with a dot . and are valid only after a global label until the next global label occurs:

main:             // global label
     ld r0, #10
.1:               // local label valid after 'main'
     call sub1
     djnz r0, .1  // jump to local label above
     ret

sub1:             // another global label, the above '.1' is forgotten
     ld r1, #10
.1:               // hence we can define it again for `sub1`
     nop
     djnz r1, .1  // jump to the '.1' label inside 'sub1'
     ret

Examples

Please see directory src/main/examples for example files used to build internal ROM, ROM and video ROM for the JU+TE computer (East-German DIY computer from 1988).