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Production Info
Submitted by XmikeX on 16 December 2018
Correction:
f9b6 e0 15 cpx #$15 -- this value here determines the max sector/block ******* |
Production Info
Submitted by XmikeX on 14 December 2018
This release combines CCR's earlier 256-byte scrolly-work ( VLC 242 ) with explorations of the Commodore 128's Autoboot Block and Serial Sequential Load function from the 128's kernal.
Autoboot information provided below, for reference, as follows:
C-128 AutoBootBlock Summary
--
; TLDR - The BootBlock
; A properly signed BootBlock at Track 1, Sector 0, is copied by the Kernal into $0b00-0bff and the following can happen:
; The BootBlock can be used perform some discreet coding function by itself, and/or to load a program from disk directly,
; or via sequential serial loading (SSL) from the kernal.
;
; CP/M Bootdisks for the C-128 and C-128 Infocom games make use of this Autoboot + "SSL" feature.
;
; TLDR - Sequential Serial Loading or AutoBootBlockLoading
; After Boot from track 1, sector 0, sequential sector loading starts at track 1 / sector 1, then sector 2...3....4....5..
; After sector 20 of track 1, the next sector it loads will be track 2, sector 0...1...2.....3.....4.....5... and so on
; This form of loading allows for up to 256 blocks to be loaded.
;
; KERNAL is hardcoded for 1541/71 format, as noted below. The 1581 was unavailable at the time the C128 kernal was being created.
;
; f9b3 a6 c2 ldx $c2
; f9b5 e8 inx
; f9b6 e0 15 cpx #$15 -- this value here determines the max track
; f9b8 90 04 bcc $f9be
; f9ba a2 00 ldx #$00
; f9bc e6 c1 inc $c1
; f9be 86 c2 stx $c2
; f9c0 8a txa
; f9c1 20 fb f9 jsr $f9fb
; f9c4 8d 00 01 sta $0100
; f9c7 8e 01 01 stx $0101
; ...............etc
;
; This is relevant for a 1581 or CMD disk, since they have more than 21 sectors/track in native mode - these will not be loaded.
; Modifying the ROM kernal code above to suit larger max value for sectors/track will result in problems and incompatibilities
; for any bootloaded software laid down on 1581 that asserts itself to the 1541/71 sector/track bootload-layout. |
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