Template for Mattel Aquarius extension ROM (with header signature)

aq_romext.asm

; Basic template of a Mattel Aquarius extension ROM
;   build: z80asm -o aq_romext.bin aq_romext.asm
;   run: mame aquariusp -bp . -cart1 aq_romext.bin

; uncomment the following block to create a 16K ROM
;org 0xc000
; ...
; ### lower part of a 16K ROM ###
; ...
;	ds 0xe000 - $

; ### Header ###

; can be customized
H0: equ 0
H1: equ 0
H2: equ 0
H3: equ 0
H4: equ 0
H6: equ 0
H8: equ 0
HA: equ 0
HC: equ 0

; signature: fixed values
H5: equ 0x9c
H7: equ 0xb0
H9: equ 0x6c
HB: equ 0x64
HD: equ 0xA8
HF: equ 0x70


HE: equ (HF - 0x4e - (H3 + H4 + H5 + H6 + H7 + H8 + H9 + HA + HB + HC + HD)) & 0xff

if H3 == 0xf7
error
endif

org 0xe000
; ROM signature
	db H0
	db H1
	db H2
	db H3
	db H4
	db H5
	db H6
	db H7
	db H8
	db H9
	db HA
	db HB
	db HC
	db HD
	db HE
	db HF

; ### high part of the ROM ###

PRNCHR: equ 0x1d94

start:
	ld	a,'@'
	call    PRNCHR

hang:
	jp hang

	ds 0x10000 - $	; pad to the ROM size

Typically based purely on CPU speed. Porting the code to different Z80 platforms with differing CPU speeds, the outputting sound is faster or slower, with a different pitch. However most 1-bit player engines have some sort of speed controlling loop.
Out of interest, BinTracker Windows version was released two days ago by Utz. https://github.com/bintracker/bintracker/releases
Outputs ZX Spectrum asm, change the sound port, re-assemble, and essentially you have a music sound tracker for the Aquarius.

Hi
Using your header, Ive managed to get another three working that previously didn't work with the previous hacked header that I was attempting to use. So thanks heaps.
Ive been using the old VirtualAquarius and MESS emulators, since I can't get anything else to work (MAME, Aqualite). However, I can only get players that are under 8k working (Assembled to $E000). Anything to $C000 just fails unfortunately. Aquarius stuff just seems very very 'finicky' to me.

Various stuff is here if interested: https://github.com/bushy555/Aquarius_1-bit_music

Hi @bushy555, briefly looking at your work to port to Aquarius, I could notice a few things:

• in order to be accepted by mame, ROM files have to be exactly 8K or 16K
• some engines (at least juston) rely on modifying the code (inject delay values or addresses). This is not possible when the code executes from ROM. 2K of RAM are available at 0x3800 if you need to store values.

Thanks. Makes so much more sense.