Block device peripheral and SBFS file system implemented.

2026-08-16 14:03:29 -04:00
parent 04dfcd707b
commit eff6902bcf
36 changed files with 3251 additions and 31 deletions
@@ -0,0 +1,143 @@
+; Storage.
+;
+; The disk is a block device and nothing more. It knows numbered blocks of 256 bytes and
+; has never heard of a file, which is deliberate: a filesystem is software this machine
+; will run rather than something the host does on its behalf. A disk that understood
+; filenames would be the emulator doing the work while the machine pretended it had.
+;
+; Its buffer is one block, and like any memory a device brings, it is unreachable until
+; it is registered as a bank and gone through with the controller.
+;
+; Between writing and reading the buffer is scrubbed, so a stale copy of the message
+; sitting in it cannot make a broken read look like a working one.
+;
+; The image is made fresh for every run of the suite, so block 3 is zeroes before this
+; program touches it.
+;
+; Correct output is:
+;   00                the write worked
+;   from the disk     block 3 came back
+;   02                a block past the end of the image is an error, not a fault
+
+#Include print.asm
+
+#Program
+
+start:
+  ; The disk's buffer becomes bank 5.
+  INIA 0d5
+  OUTA 0xE3
+  INIA 0x20
+  OUTA 0xE2
+  INIA 0x03
+  OUTA 0xE8
+
+  ; Put the message into the buffer and write it to block 3.
+  SETD.0 Message
+  CALL aimSourceData
+  CALL aimDestBuffer
+  INIA 0d16
+  CALL setLength
+  INIA 0x01
+  OUTA 0xE8
+
+  CALL selectBlockThree
+  INIA 0x02
+  OUTA 0x22             ; Write.
+  INA 0x23
+  CALL printByteHex
+  CALL lineFeed
+
+  ; Scrub the buffer, so what comes back has to have come off the disk.
+  CALL aimDestBuffer
+  INIA 0x2D             ; '-' as the fill byte.
+  OUTA 0xE2
+  INIA 0d16
+  CALL setLength
+  INIA 0x02
+  OUTA 0xE8             ; Fill.
+
+  CALL selectBlockThree
+  INIA 0x01
+  OUTA 0x22             ; Read.
+
+  ; Bring the block into Data Memory and print it.
+  INIA 0d5
+  OUTA 0xE0
+  RSTA
+  OUTA 0xE1
+  OUTA 0xE2
+  SETD.0 Landing
+  CALL aimDestData
+  INIA 0d16
+  CALL setLength
+  INIA 0x01
+  OUTA 0xE8
+
+  SETD.0 Landing
+  CALL printString
+  CALL lineFeed
+
+  ; A block past the end of the image says so in Status rather than stopping the machine.
+  ; A disk that cannot read a block is an ordinary thing that happens to working programs.
+  INIA 0xFF
+  OUTA 0x20
+  INIA 0xFF
+  OUTA 0x21
+  INIA 0x01
+  OUTA 0x22
+  INA 0x23
+  CALL printByteHex
+  CALL lineFeed
+  HALT
+
+selectBlockThree:
+  RSTA
+  OUTA 0x20
+  INIA 0d3
+  OUTA 0x21
+  RET
+
+aimSourceData:
+  INIA 0d1
+  OUTA 0xE0
+  PSHD.0
+  POPA
+  POPB
+  OUTB 0xE1
+  OUTA 0xE2
+  RET
+
+aimDestData:
+  INIA 0d1
+  OUTA 0xE3
+  PSHD.0
+  POPA
+  POPB
+  OUTB 0xE4
+  OUTA 0xE5
+  RET
+
+aimDestBuffer:
+  INIA 0d5
+  OUTA 0xE3
+  RSTA
+  OUTA 0xE4
+  OUTA 0xE5
+  RET
+
+setLength:
+  PSHA
+  RSTA
+  OUTA 0xE6
+  POPA
+  OUTA 0xE7
+  RET
+
+#Data
+
+Message:
+"from the disk"
+
+Landing:
+  #Reserve 0d20