Vector 4/8086 ROM Docs – VECTOR 4/8086 - Winchester Load Path (1066h / 1072h)

Listing: 06-winchester-load.asm · driver 05-helpers-disk.asm
Related: Floppy load path · Winchester parameters · How to boot hard disk

Entries:

Path	How reached
`1066`	Menu key W (`07F4` table) or vector `0012` → `JP 1066`
`1072`	Core helper: called by `1066`, and by auto-boot `@0140`
Auto-boot `@012B`	If `(09AA)≠0`: print LOADING → `15AA` → `CALL 1072` → success `CALL 2400`

Unit: A = 00h (Winchester / fixed disk)
First sector: LBA 0 → RAM 2400h via 1638 (not 14A8)

High-level flow

Menu [W] / vector 0012
        │
        ▼
1066  CALL 1072
        │
        ├─ NZ  → JP 155D     ; hardware error (A = code 1..8)
        ├─ C   → JP 11C0     ; system error (A = 2 or 5)
        └─ OK  → JP 2400h    ; run SYSTEM image (no return)

1072  (helper — also used by auto-boot)
        │
        ├─ (67F6)=0
        ├─ A=0, CALL 1600           ; select unit 0, wait ready
        ├─ A=0, C=1, CALL 15DE      ; restore / home
        ├─ HL=2400, A=0, B=1, DE=0, C=0
        │     CALL 1638             ; read 512 bytes → 2400h
        │
        ├─ (2402)==02h ?
        │     no  → A=2, SCF, RET   ; #2 UNRECOGNIZED MEDIA FORMAT
        │
        ├─ (09AA)==(240B) ?
        │     no  → A=5, SCF, RET   ; #5 CONFIGURATION MISMATCH
        │
        └─ A=0, HL still @240B area
              CALL 1434             ; geometry FROM HEADER (A<3 path)
              OR A / RET            ; NZ = HW error from restore

Auto-boot success differs only in transfer:

CALL 1072 success → putchar 18h → CALL 2400h   ; not JP

(Menu W uses JP 2400.)

Step detail — `1072`

1. Clear load flag

1072  XOR A
1073  LD (67F6h), A

Same flag floppy clears at 104D before type dispatch.

2. Select unit 0 — `CALL 1600`

1076  LD A, 00h
1078  CALL 1600h
107B  OR A / RET NZ          ; HW error → caller

1600 unit differences (A=0 vs A=3 floppy):

	Winchester `A=0`	Floppy `A=3`
Ready mask L	`D0h`	`F0h`
Timeout DE	`1388h`	`7530h`
Error H seed	`H` starts 2 then `INC H` → 3	`H=2`
`168B` A6 pattern	`A*8 \\| A0h \\| (C&7)` (A<3 branch)	`(A-3)*2 \\| 38h \\| (C&1)`

Winchester uses the shorter ready timeout path (OR A is Z → 161B).

3. Restore — `CALL 15DE`

107D  LD A, 00h
107F  LD C, 01h
1081  CALL 15DEh
1084  OR A / RET NZ

15DE with unit 0 and C bit0 set:

CALL 168B
A = 10h
if unit≥3: … else if C bit0: A |= 06h   → OUT (A7), 16h
wait 16BC; fail → error #5 DRIVE RESTORE

4. Read LBA 0 — `CALL 1638` (direct)

1086  LD HL, 2400h
1089  LD A, 00h          ; unit 0 (passed through 168B)
108B  LD B, 01h          ; address reg B → OUT (A3)
108D  LD DE, 0000h       ; LBA / sector address D,E → A5,A4
1090  LD C, 00h
1092  CALL 1638h
1095  OR A / RET NZ

Important: Floppy first sector uses 14A8 (geometry-aware multi-sector). Winchester first sector uses 1638 directly (controller INIR path, 512 bytes to HL).

1638 for unit 0:

Ready mask D0h (same as select)
OUT (A7), 20h read command
On success: INIR×2 from port A0 → 512 bytes at 2400h

5. Header checks

Format id

1097  LD A, (2402h)
109A  CP 02h
109C  JR Z, 10A3h
109E  XOR A
109F  LD A, 02h
10A1  SCF
10A2  RET                 ; CF=1, A=2 → 11C0 UNRECOGNIZED MEDIA FORMAT

Configuration match (Winchester-specific)

10A3  LD A, (09AAh)       ; ROM config id (dump: C8h)
10A6  LD HL, 240Bh
10A9  CP (HL)             ; must match header +0Bh
10AA  JR Z, 10B1h
10AC  XOR A
10AD  SCF
10AE  LD A, 05h
10B0  RET                 ; CF=1, A=5 → 11C0 CONFIGURATION MISMATCH

Floppy path does not compare (09AA) to (240B) on the simple boot branch. Winchester requires ROM config byte == disk header config id.

6. Geometry from header — `CALL 1434` with `A=0`

10B1  LD A, 00h
10B3  CALL 1434h          ; HL still 240Bh after CP
10B6  OR A
10B7  RET

Because A < 3, 1434 takes the header geometry branch at 1481 (not ROM table @0831):

; HL entered as 240B
INC HL × 5                ; → 2410
(2006) = (2410)           ; shift / block param
(2003) = word (2411)      ; geometry word (SPT-related, etc.)
(2008) = (2413)
(2007) = 0 or 1 from (2414)
C = (2007)
A = (2009) = 0
JP 15DE                   ; second restore with new geometry

So after a successful Winchester load helper, driver vars are programmed from the SYSTEM header, not from the floppy media table FA–FF.

Step detail — menu wrapper `1066`

1066  CALL 1072h
1069  JP NZ, 155Dh         ; A = HW code, print hardware error
106C  JP C,  11C0h         ; A = 2 or 5, print system error
106F  JP 2400h             ; run image at 2400 (never returns)

No type field test, no directory search, no JP FF4C.

Header fields used (Winchester)

Off	Addr	Check / use
`+02`	`2402`	Must be `02h` (else error #2)
`+0B`	`240B`	Must equal ROM `(09AA)` (else error #5)
`+10`…`+14`	`2410`…	Geometry loaded into `2003`–`2008` via `1434` A<3
`+00`	`2400`	Execution entry: `JP`/`CALL 2400` (code starts here)

Not checked on Winchester path: (2442) flags, type 21h, simple-boot nonzero word test (execution is unconditional after helper OK).

Differences from floppy (`1000`)

Item	Floppy `1000`	Winchester `1066`/`1072`
Unit	`A=3`	`A=0`
Menu key	`F`	`W`
First select	`1600` A=3	`1600` A=0
Geometry before read	`1434` B=`FEh`, table `@0831`	None before first read
First sector API	`14A8` (1 sector)	`1638` direct
Format fail code	#1 UNRECOGNIZED SYSTEM DISKETTE	#2 UNRECOGNIZED MEDIA FORMAT
Config `(09AA)` vs `(240B)`	Not on simple path	Required (#5 on mismatch)
`(2442)` flags / type	Required; type `21h` → full file load	Not used
Success transfer	`JP 2400` or type21 → `FF4C`	Always `JP 2400` (menu) / `CALL 2400` (auto-boot)
Multi-sector SYSTEM FILE	Type `21h` path `10B8`	No — single sector then run
Second `1434`	From `(2415)`/`(2442)` with A=3	From header with A=0 after validate
Auto-boot	Not via `1000`	`CALL 1072` from `0140` if `(09AA)≠0`

Shared helpers

Addr	Role	Winchester use	Floppy use
`1600`	Select unit / ready wait	Unit 0	Unit 3
`15DE`	Restore / seek-class cmd	After select; again from `1434`	From `1434` after geometry
`1638`	Low-level 512B read	First sector	Via `14A8` only
`14A8`	Geometry-aware multi-read	Not in `1072`	First sector + type21
`1434`	Geometry + restore	A<3 header path	A≥3 table `@0831`
`168B`	Program A2–A6	Both	Both
`16BC`	Wait controller ready	Both	Both
`15CE`	Status return / cleanup	Both	Both
`155D`	HW error print	From `1066` if NZ	Throughout `1000`
`11C0`	Sys error print	From `1066` if CF	Format/type failures
`15AA`	Controller probe	Auto-boot before `1072`	Menu start; not required by `1000` itself

Controller ports (same family)

Port	Use
`A0`	Data INIR
`A1`	Sense (probe `15AA`)
`A2`–`A5`	Address
`A6`	Unit control
`A7`	Command / status
`A8`	Gate (`15AA`)

Error summary (Winchester)

Condition	Flags	A	Printer	Message
Select/restore/read fail	NZ, NC	1–8	`155D`	Hardware table
`(2402)≠02`	CF	2	`11C0`	UNRECOGNIZED MEDIA FORMAT
`(240B)≠(09AA)`	CF	5	`11C0`	CONFIGURATION MISMATCH

Related: `12FB` Winchester touch (type 21h finish only)

After a floppy type-21h bulk load, 12FB may optionally:

If (09AA)≠0, match drive records, CALL 1434 A=0
Read Winchester LBA 0 → 2200 via 14A8
Verify (2202)==02 and config ids
Scan sectors from LBA 36h for type match to (2442)
Copy 13 bytes from 222B → 6723

That is not part of menu [W] / 1072; it only enriches the floppy type-21h handoff workspace.

Annotated outline

; --- menu / vector ---
1066  CALL 1072
      JP NZ,155D / JP C,11C0 / JP 2400

; --- helper (menu + auto-boot) ---
1072  (67F6)=0
      A=0 / CALL 1600          ; unit 0
      A=0,C=1 / CALL 15DE      ; restore
      HL=2400, A=0,B=1,DE=0,C=0 / CALL 1638
      require (2402)=02 else A=2 SCF RET
      require (09AA)=(240B) else A=5 SCF RET
      A=0 / CALL 1434          ; geometry from header @2410+
      RET                      ; Z = success

Open questions

Exact CHS/LBA layout of Winchester sector 0 beyond the fields above (need media dump).
Whether any Winchester media uses type-21h-style multi-sector SYSTEM (current code path does not).
Meaning of B=01 on the initial 1638 call (address byte to A3) vs floppy geometry conversion.

If anyone has additional information, manuals, schematics, or software for this Vector 4/8086 CPU variant (Vector Graphic SX/5000), please contact me.

VECTOR 4/8086 - Winchester Load Path (1066h / 1072h)From Inside a Vector Graphic SX/5000 (Vector 4/8086 variant)