High-Density Disk Interface#
The HDI is the interface for connecting up to 4 standard drives to the XL/XE. You can mix 3,5" and 5,25" floppies at will. Required is that the drive supports the Disk Change signal at pin 34 of the Shugart bus. It doesn't support Medium Density (128 bytes/sector in MFM mode and 1.2 MB drives). Maximum transfer rate: 500 Kbit/s (1.44 MByte disks).
The HDI has been developed in 1991 by Erhard Pütz (FloppyDoc).
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Manual:#
HDI Manual: HDI Interface/HDI_Manual.pdf
HDI Schematics 
(PDF: HDI Interface/sch_hdi.pdf)
HDI High Speed SIO#
01000 * High-Speed SIO-Driver, will 01010 * be relocated by HDI and 01020 * send to computer. 01030 ; 01040 USIOA LDA $0301 ;DUNIT 01050 BNE SIO2 01060 LDX #$08 01070 DLWTBLL STA LWTBL-1,X ;$F614 01080 DEX 01090 BNE DLWTBLL 01100 RTS 01110 SIO2 TAX 01120 REL01 LDA LWTBL-1,X ;$F614 01130 BNE SIO3 01140 LDA #$28 01150 REL02 STA LWTBL-1,X ;$F614 01160 LDY #$07 01170 SIOCL LDA $0302,Y ;DCOMND 01180 PHA 01190 REL03 LDA C3F,Y ;$F60D 01200 STA $0302,Y ;DCOMND 01210 DEY 01220 BPL SIOCL 01230 REL04 JSR SIO3 ;$F450 01240 LDX $0301 ;DUNIT 01250 LDY $0303 ;DSTATS 01260 BMI SIO21 01270 LDA $01 01280 REL05 STA LWTBL-1,X ;$F614 01290 SIO21 LDY #$00 01300 SIO21CL PLA 01310 STA $0302,Y ;DCOMND 01320 INY 01330 CPY #$08 01340 BCC SIO21CL 01350 SIO3 SEI 01360 TXA 01370 ORA #$30 01380 STA $023A ;CDEVIC 01390 LDA $0302 ;DCOMND 01400 STA $023B ;CCOMND 01410 LDA $030A ;DAUX1 01420 STA $023C ;CAUX1 01430 LDA $030B ;DAUX2 01440 STA $023D ;CAUX2 01450 REL06 LDA LWTBL-1,X ;$F614 01460 STA $D204 ;AUDF3 01470 TSX 01480 STX $3F ;FEOF 01490 LDA #$02 01500 STA $37 ;DRETRY 01510 IO11 LDA #$07 01520 STA $36 ;CRETRY 01530 IO12 LDA #$34 01540 STA $D303 01550 LDA #$00 01560 STA $30 ;STATUS 01570 STA $3E ;FTYPE 01580 STA $35 ;BUFEND+1 01590 STA $D206 ;AUDF4 01600 LDA #$3A 01610 STA $32 ;BUFADR 01620 LDA #$02 01630 STA $33 ;BUFADR+1 01640 ASL 01650 STA $34 ;BUFEND 01660 REL07 JSR SEND1 ;$F4DC 01670 LDA $0304 ;DBUFLO 01680 STA $32 ;BUFADR 01690 LDA $0305 ;DBUFHI 01700 STA $33 ;BUFADR+1 01710 LDA $0308 ;DBYTLO 01720 STA $34 ;BUFEND 01730 LDA $0309 ;DBYTHI 01740 STA $35 ;BUFEND+1 01750 LDA $0303 ;DSTATS 01760 BPL IO2 01770 REL08 JSR SEND1 ;$F4DC 01780 IO2 DEC $3E ;FTYPE 01790 REL09 JSR SETTI1 ;$F544 01800 BIT $0303 ;DSTATS 01810 BVC IO3 01820 REL10 JSR GETA1 ;$F521 01830 IO3 LDA #$A0 01840 STA $D207 ;AUDC4 01850 LDA $10 01860 STA $D20E ;IRQEN 01870 REL11 JSR CLRTI1 ;$F576 01880 LDA $30 ;STATUS 01890 BEQ IO4 01900 DEC $37 ;DRETRY 01910 BNE IO11 01920 IO4 TAY 01930 BNE IO5 01940 INY 01950 IO5 STY $0303 ;DSTATS 01960 CLI 01970 RTS 01980 SEND1 LDY #$00 01990 SE1 INY 02000 BNE SE1 02010 LDA #$23 02020 REL12 JSR POKEY ;$F5F7 02030 LDA ($32),Y ;BUFADR 02040 STA $31 ;CHKSUM 02050 STA $D20D ;SEROUT 02060 INY 02070 BNE SE3 02080 SE2 LDA ($32),Y ;BUFADR 02090 REL13 JSR PUTBYTE ;$F5D4 02100 INY 02110 BNE SE3 02120 INC $33 ;BUFADR+1 02130 DEC $35 ;BUFEND+1 02140 LDX #$E0 02150 SEWL INX 02160 BNE SEWL 02170 SE3 CPY $34 ;BUFEND 02180 BNE SE2 02190 LDA $35 ;BUFEND+1 02200 BNE SE2 02210 LDA $31 ;CHKSUM 02220 REL14 JSR PUTBYTE ;$F5D4 02230 SEO1 LDA $D20E ;IRQST 02240 AND #$08 02250 BNE SEO1 02260 LDY #$03 02270 REL15 JSR STOUTX0 ;$F578 02280 LDA #$C0 02290 STA $D20E ;IRQEN 02300 BNE RDQUIT 02310 GETA1 LDY #$00 02320 STY $31 ;CHKSUM 02330 GE1 JSR GETBYTE ;$F5B1 02340 STA ($32),Y ;BUFADR 02350 REL16 JSR ADDSUM ;$F5EF 02360 INY 02370 BNE GE2 02380 INC $33 ;BUFADR+1 02390 DEC $35 ;BUFEND+1 02400 GE2 CPY $34 ;BUFEND 02410 BNE GE1 02420 LDA $35 ;BUFEND+1 02430 BNE GE1 02440 REL17 JSR GETBYTE ;$F5B1 02450 CMP $31 ;CHKSUM 02460 BNE ERR8F 02470 RTS 02480 SETTI1 LDA $0306 ;DTIMLO 02490 ROR 02500 ROR 02510 TAY 02520 AND #$3F 02530 TAX 02540 TYA 02550 ROR 02560 AND #$C0 02570 TAY 02580 REL18 JSR STOUT ;$F57A 02590 RDQUIT LDA #$3C 02600 STA $D303 02610 LDA #$13 02620 REL19 JSR POKEY ;$F5F7 02630 REL20 JSR GETBYTE ;$F5B1 02640 CMP #$41 02650 BEQ CLRTI1 02660 CMP #$43 02670 BEQ CLRTI1 02680 CMP #$45 02690 BEQ ERR90 02700 LDA #$8B 02710 BNE ERR 02720 ERR90 LDA #$90 02730 STA $30 ;STATUS 02740 CLRTI1 LDY #$00 02750 STOUTX0 LDX #$00 02760 STOUT LDA ERRABS ;$F 02770 STA $0226 ;CDTMA1 02780 STOU2 LDA ERRABS+1 ;$F 02790 STA $0227 ;CDTMA1+1 02800 LDA #$01 02810 JMP $E45C ;Setze CDTMV1 02820 ERRABS .DA ERR8A ;$F 02830 IOER80 LDX $3F ;FEOF 02840 TXS 02850 LDA #$80 02860 STA $30 ;STATUS 02870 BNE EABS3 02880 ERR8F LDA #$8F 02890 .HX 2C 02900 ERR8A LDA #$8A ;Timeout 02910 ERR STA $30 ;STATUS 02920 LDX $3F ;FEOF 02930 TXS 02940 LDA $3E ;FTYPE 02950 BMI ERRA 02960 DEC $36 ;CRETRY 02970 BEQ ERRA 02980 REL21 JMP IO12 ;$F47A 02990 ERRA LDA #$28 03000 STA $D204 ;AUDF3 03010 EABS3 JMP IO3 ;$F4C1 03020 GETBYTE LDA $D20E ;IRQST 03030 BPL IOER80 03040 AND #$20 03050 BNE GETBYTE 03060 LDA #$DF 03070 STA $D20E ;IRQEN 03080 LDA #$E0 03090 STA $D20E ;IRQEN 03100 LDA $D20F ;SKSTAT 03110 STA $D20A ;SKRES 03120 BPL ERR8A 03130 AND #$20 03140 BEQ ERR8A 03150 LDA $D20D ;SERIN 03160 RTS 03170 PUTBYTE TAX 03180 PUTA1 LDA $D20E ;IRQST 03190 AND #$10 03200 BNE PUTA1 03210 LDA #$EF 03220 STA $D20E ;IRQEN 03230 LDA #$D0 03240 STA $D20E ;IRQEN 03250 TXA 03260 STA $D20D ;SEROUT 03270 LDX $D20E ;IRQST 03280 BPL IOER80 03290 ADDSUM CLC 03300 ADC $31 ;CHKSUM 03310 ADC #$00 03320 STA $31 ;CHKSUM 03330 RTS 03340 POKEY STA $D20F ;SKCTL 03350 STA $D20A ;SKRES 03360 LDA #$28 03370 STA $D208 ;AUDCTL 03380 LDA #$A8 03390 STA $D207 ;AUDC4 03400 LDA #$F8 03410 STA $D20E ;IRQEN 03420 RTS 03430 C3F .HX 3F40 03440 .DA $0001 03450 .DA $0001 03460 .DA $0001 03470 LWTBL .BL 8,0 03480 USIOE 03490 ABSTBL .DA DLWTBLL+1,REL01+1,REL02+1,REL03+1,REL04+1,REL05+1,REL06+1 03500 .DA REL07+1,REL08+1,REL09+1,REL10+1,REL11+1,REL12+1,REL13+1 03510 .DA REL14+1,REL15+1,GE1+1,REL16+1,REL17+1,REL18+1,REL19+1 03520 .DA REL20+1,STOUT+1,STOU2+1,ERRABS,REL21+1,EABS3+1
