X68000

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Sharp X68000

The Sharp X68000 is a home computer created by Sharp Corporation. It was first released in 1987 and sold only in Japan.

The initial model has a 10 MHz Motorola 68000 CPU, 1 MB of RAM, and lacks a hard drive. The final model was released in 1993 with a 25 MHz Motorola 68030 CPU, 4 MB of RAM, and optional 80 MB SCSI hard drive. RAM in these systems is expandable to 12 MB, though most games and applications do not require more than 2 MB.

The X68000 has graphics hardware similar to arcade video games of the late-1980s, with custom coprocessors supporting scrolling, tiled backgrounds, and large numbers of sprites. Sound is supplied through multiple sound chips supporting 8 channels of FM synthesis and one channel of adaptive differential pulse-code modulation audio, which are mixed down to 2 analog stereo channels via a DAC chip. As such, video gaming was a major use of the X68000.

The X68000 runs an operating system called Human68k which was developed for Sharp by Hudson Soft. An MS-DOS-workalike, Human68k features English-based commands very similar to those in MS-DOS;

Setting up

Memory map

address 	vector 	Function 	
$000000 	$00 	SSP after reset 	
$000004 	$01 	PC after reset 	
$000008 	$02 	Bus error 	
$00000c 	$03 	Address error 	
$000010 	$04 	Unknown instruction 	
$000014 	$05 	Division by 0 	
$000018 	$06 	CHK instruction 	
$00001c 	$07 	TRAPV instruction, FTRAPcc instruction 	
$000020 	$08 	Privilege violation 	
$000024 	$09 	Trace exception 	
$000028 	$0a 	Unsupported instruction line 1010 emulator (SX call) 	
$00002c 	$0b 	? line 1111 emulator (DOS call, floating point operation) 	
$000030 	$0c 	Unused 	
$000034 	$0d 	FPU Protocol violation exception handling 	
$000038 	$0e   	Formatting error exception handling 	
$00003c 	$0f 	Uninitialized Interrupt 	
$000040 	$10 	Unused 	
$000044 	$11 	? 	
$000048 	$12 	? 	
$00004c 	$13 	? 	
$000050 	$14 	? 	
$000054 	$15 	? 	
$000058 	$16 	? 	
$00005c 	$17 	? 	
$000060 	$18 	Spurious Interrupt 	
$000064 	$19 	Level 1 Interrupt (auto vector) 	
$000068 	$1a 	? 	
$00006c 	$1b 	? 	
$000070 	$1c 	? 	
$000074 	$1d 	? 	
$000078 	$1e 	? 	
$00007c 	$1f 	? 	
$000080 	$20 	trap #0 	
$000084 	$21 	? #1 	
$000088 	$22 	? #2 	
$00008c 	$23 	? #3 	
$000090 	$24 	? #4 	
$000094 	$25 	? #5 	
$000098 	$26 	? #6 	
$00009c 	$27 	? #7 	
$0000a0 	$28 	? #8 (reserved for system) 	
$0000a4 	$29 	? #9 (OS debugger) 	
$0000a8 	$2a 	? #10 (reset & power off) 	
$0000ac 	$2b 	? #11 (BREAK key) 	
$0000b0 	$2c 	? #12 (COPY key) 	
$0000b4 	$2d 	? #13 (CTRL+C) 	
$0000b8 	$2e 	? #14 (error processing) 	
$0000bc 	$2f 	? #15 (IOCS call) 	
$0000c0 	$30 	FPU BSUN 	
$0000c0 	$30 	FPU BSUN 	
$0000c4 	$31 	? INEX1,INEX2 	
$0000c8 	$32 	? DZ 	
$0000cc 	$33 	? UNFL 	
$0000d0 	$34 	? OPERR 	
$0000d4 	$35 	? OVFL 	
$0000d8 	$36 	? SNAN 	
$0000dc 	$37 	??? 	
$0000dc 	$37 	Unused 	
$0000e0 	$38 	MMU 	
$0000e4 	$39 	? 	
$0000e8 	$3a 	? 	
$0000ec 	$3b 	Unused 	
$0000fc 	$3f 	Unused 	
$000100 	$40 	MFP RTC Alarm/1Hz 	
$000104 	$41 	MFP External power OFF 	
$000118 	$42 	MFP Front switch OFF 	
$00010c 	$43 	MFP FM Audio source 	
$000110 	$44 	MFP Timer-D (Used with BG processing) 	
$000114 	$45 	MFP Timer-C (Mouse/cursor/FDD control, etc.) 	
$000118 	$46 	MFP V-DISP 	
$00011c 	$47 	MFP RTC Clock 	
$000120 	$48 	MFP Timer-B 	
$000124 	$49 	MFP Key serial output error 	
$000128 	$4a 	MFP Key serial output empty 	
$00012c 	$4b 	MFP Key serial input error 	
$000130 	$4c 	MFP Key serial input 	
$000134 	$4d 	MFP Timer-A 	
$000138 	$4e 	MFP CRTC*IRQ 	
$00013c 	$4f 	MFP H-SYNC 	
$000140 	$50 	SCC(B) Transmission buffer empty 	
$000144 	$51 	SCC(B) '' 	
$000148 	$52 	SCC(B) External/status changes 	
$00014c 	$53 	SCC(B) '' 	
$000150 	$54 	SCC(B) Incoming character validity (Mouse 1 byte input) 	
$000154 	$55 	SCC(B) '' 	
$000158 	$56 	SCC(B) Special Rx condition 	
$00015c 	$57 	SCC(B) '' 	
$000160 	$58 	SCC(A) Transmission buffer empty 	
$000164 	$59 	SCC(A) '' 	
$000168 	$5a 	SCC(A) External status changes 	
$00016c 	$5b 	SCC(A) '' 	
$000170 	$5c 	SCC(A) Incoming character validity (RS-232C 1 byte input) 	
$000174 	$5d 	SCC(A) '' 	
$000178 	$5e 	SCC(A) Special Rx Condition 	
$00017c 	$5f 	SCC(A) '' 	
$000180 	$60 	I/O FDC status interruption 	
$000184 	$61 	I/O FDC insertion/discharge interruption 	
$000188 	$62 	I/O HDC status interruption 	
$00018c 	$63 	I/O Printer ready interruption 	
$000190 	$64 	DMAC #0 End (FDD) 	
$000194 	$65 	DMAC #0 Error ('') 	
$000198 	$66 	DMAC #1 End (SASI) 	
$00019c 	$67 	DMAC #1 Error ('') 	
$0001a0 	$68 	DMAC #2 End (IOCS _DMAMOVE,_DMAMOV_A,_DMAMOV_L) 	
$0001a4 	$69 	DMAC #2 Error ('') 	
$0001a8 	$6a 	DMAC #3 End (ADPCM) 	
$0001ac 	$6b 	DMAC #3 Error ('') 	
$000200 	$6c 	SPC SCSI interruption (Internal SCSI) 	
$000204 	$6d 	Unused 	
$0003d4 	$f5 	Unused 	
$0003d8 	$f6 	SPC SCSI interruption (SCSI board) 	
$0003dc 	$f7 	Unused 	
$0003fc 	$ff 	Unused 	
0x000000 	RAM area 	
$c00000 	Graphics Vram � Page 0 	
$c80000 	Graphics Vram � Page 1 (256/16 color only) 	
$d00000 	Graphics Vram � Page 2 (16 color only)
$d80000 	Graphics Vram � Page 3 (16 color only) 	
$e00000 	Text Vram � Bitplane 0 	
$e20000 	Text Vram � Bitplane 1
$e40000 	Text Vram � Bitplane 2
$e60000 	Text Vram � Bitplane 3
$e80000 	1.w 	R00 Horizontal total 	
$e80002 	1.w 	R01 Horizontal synchronization end position timing 	
$e80004 	1.w 	R02 Horizontal display start position 	
$e80006 	1.w 	R03 Horizontal display end position 	
$e80008 	1.w 	R04 Vertical total 	
$e8000a 	1.w 	R05 Vertical synchronization end position timing 	
$e8000c 	1.w 	R06 Vertical display start position 	
$e8000e 	1.w 	R07 Vertical display end position 	
$e80010 	1.w 	R08 External synchronization horizontal adjust: Horizontal position tuning 	
$e80012 	1.w 	R09 Raster number: Used for raster interruption 	
$e80014 	1.w 	R10 Text Screen X coordinate 	
$e80016 	1.w 	R11 Text Screen Y coordinate 	
$e80018 	1.w 	R12 Graphics screen Scroll X0 	
$e8001a 	1.w 	R13 Graphics screen Scroll Y0 	
$e8001c 	1.w 	R14 Graphics screen Scroll X1 	
$e8001e 	1.w 	R15 Graphics screen Scroll Y1 	
$e80020 	1.w 	R16 Graphics screen Scroll X2 	
$e80022 	1.w 	R17 Graphics screen Scroll Y2 	
$e80024 	1.w 	R18 Graphics screen Scroll X3 	
$e80026 	1.w 	R19 Graphics screen Scroll Y3 	
$e80028 	1.w 	R20 Memory mode/Display mode control 	
$e8002a 	1.w 	R21 Simultaneous access/Raster copy/Quick clear plane select 	
$e8002c 	1.w 	R22 Raster copy action: Raster number 	
$e8002e 	1.w 	R23 Text screen access mask pattern 	
$e80481 	1.b 	Active Image capture/Quick clear/Raster copy control 	
$e82000 	256.w 	Graphics palette 	
$e82200 	16.w 	Text palette (Palette block 0) 	
$e82220 	240.w 	Sprite palette ('' 1-15) 	
$e82400 	1.w 	R0 (Screen mode initialization) 	
$e82500 	1.w 	R1 (Priority control) 	
$e82600 	1.w 	R2 (Special priority/screen display) - Layers On/Off
$e84000 	DMAC (HD63450) 	
$e86000 	Memory controller privileged access settings (OHM/ASA) 	
$e88000 	MFP (MC68901) 	
$e8a000 	RTC (RP5C15) 	
$e8c000 	Printer port 	
$e8e001 	#1 Contrast 	
$e8e003 	#2 Display/3D Shutter Glasses (Bit 0=Right Eye / Bit 1 = Left Eye)
$e8e005 	#3 Color image unit (bit 4-0) 	
$e8e007 	#4 Keyboard/NMI/dot clock 	
$e8e009 	#5 ROM/DRAM Wait 	
$e8e00b 	#6 MPU Classification/Operation clock 	
$e8e00d 	#7 SRAM Write 	
$e8e00f 	#8 Unit power OFF 	
$E90001 	FM Synthesizer (YM2151) - Register Address Write port 	
$E90003 	FM Synthesizer (YM2151) - Data R/W port 	
$E92000 	ADPCM (MSM6258V) 	
$E94000 	Floppy disk controller (FDC) (uPD72065) 	
$E94005 	Floppy drive monitor (IOSC) 	
$E96000 	SASI 	
$E98000 	ESCC (Z8530) 	
$E9A000 	PPI (82C55) 	
$E9C000 	I/O selector (IOSC) 	
$E9E000 	I/O expansion area (Sharp reserved) 	
$EB0000 	Sprite register (CYNTHIA) 	
$EB8000 	Sprite VRAM 	
$EC0000 	I/O expansion area (User) 	
$ed0072 	2.b 	SX-Window environment flag (While in use with "SX") 	
$ed0074 	1.b 	Standard double-click time / 10 	
$ed0075 	1.b 	Mouse speed / 2 	
$ed0076 	1.b 	Text palette hue (HSV) 	
$ed0077 	1.b 	
$ed0078 	1.b 	Brightness palette 0-3 5bit??? 	
$ed007b 	1.b 	Printer drive (PRTD) ID 	
$ed007c 	1.b 	SRAM info version#, screen status storage, start screen storage 	
$ed007d 	1.b 	Desktop background (PICT) ID 	
$ed007e 	1.b 	Screen mode 	
$ed007f 	17.b 	Reserved for system use (X68030) 	
$ed0090 	1.b 	Standard cache status (bit=0: off 1:on) 	
$ed0091 	1.b 	OPM music during startup (0: OFF -1: ON) 	
$ed0092 	1.b 	10MHz Proper wait value 	
$ed0093 	1.b 	16MHz '' 	
$ed0094 	108.b 	Reserved for system use 	
$ed0100 	768.b 	Head SRAM program address 	
$ed0400 	15KB 	Head SRAMDISK address 	
$ed3fff 	End of SRAM 	
$ed4000 	Backup (64KB) 	
$ee0000 	Unused (128KB) 	
$f00000 	CGROM(768KB) 	
$fc0000 	SCSI IOCS / IPL(8KB) 	
$fe0000 	ROM Debugger 	
$ff0000 	IPL / ROM IOCS

Video display

Here is a list of graphics modes 

d1.w	 
0	1024	 512 x 512	16	1	31
1	V		V	V	V	15
2	V	 256 x 256	V	V	31
3	V		V	V	V	15
4	512	 512 x 512	16	4	31
5	V		V	V	V	15
6	V	 256 x 256	V	V	31
7	V		V	V	V	15
8	V	 512 x 512	256	2	31
9	V		V	V	V	15
10	V	 256 x 256	V	V	31
11	V		V	V	V	15
12	V	 512 x 512	65536	1	31
13	V		V	V	V	15
14	V	 256 x 256	V	V	31
15	V		V	V	V	15
16	1024	 768 x 512	16	1	31
17	V	1024 x 424	V	V	24
18	V	1024 x 848	V	V	24
19	V	 640 x 480	V	V	24
20	V	 768 x 512	256	2	31
21	V	1024 x 848	V	V	24
22	V	1024 x 424	V	V	24
23	V	 640 x 480	V	V	24
24	V	 768 x 512	65536	1	31
25	V	1024 x 848	V	V	24
26	V	1024 x 424	V	V	24
27	V	 640 x 480	V	V	24


Vsync

waitVBlank:
    move.w $e88000,d0
    and.w #%00010000,d0            ;Wait for vblank to start
    beq waitVBlank
waitVBlank2:   
    move.w $e88000,d0
    and.w #%00010000,d0            ;Wait for Vblank to end
    bne waitVBlank2
    rts

Plotting to screen

When accessing using GRAM directly, you can fill the GVRAM directly in word (64k colors), byte (8 bit palette) or 4-bit 16 color mode. 

To be added

IOCS Drawing routines

Alternatively you could make use of the IOCS functions for drawing primitives. 

_PSET               equ     $b6
_POINT              equ     $b7
_LINE               equ     $b8
_BOX                equ     $b9
_FILL               equ     $ba
_CIRCLE             equ     $bb
_PAINT              equ     $bc
_SYMBOL             equ     $bd
_GETGRM             equ     $be
_PUTGRM             equ     $bf

Sound

The X68000 has a YM2151 FM Soundchip on board with 8 channels. Each channel's sound can be built up with 4 different 'slots'... meaning there are a total of 32 slots... these slots are turned on or off when the sound is triggered

For more information, check out the YM2151 specs at [1]

Additional Resources

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