X68000
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[hide]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
- Assembler: VASM
- Tools: NDC to create an XDF Disk Image containing the production
- Emulator(s): http://retropc.net/pi/xm6/index.html , https://www.retrostic.com/emulators/sharp-x68000/winx68030, https://mijet.eludevisibility.org/XM6%20Pro-68k/XM6%20Pro-68k.html
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 IOCSVideo display
To be added
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
rtsPlotting to screen
To be addedSound
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
- Assembly programming for the X68000
- [2] X68000 Technical data book
- [3] YM2151 Datasheet
- X68000 demoscene productions
- X68000 chapter in the book "The Book of CP-System"
