sltwrk.asm

    org 08000h

    ld hl, 08000h ; this memory area
    call Memory_GetSlot
    call GET_SLTWRK_FOR_SLOT
    ; retrieve pointer from SLTWRK area
    ld e,(hl)
    inc hl
    ld d,(hl)
    ; do something with it
    ;
    ;
    ret


GET_SLTWRK_FOR_SLOT:
    ; formula: SLTWRK address = FD09H + 32*primary slot + 8*expansion slot + 2*page
    ld b, a
    and 00000011b; select primary slot
    ld hl,0
    ld l,a
    add hl, hl
    add hl, hl
    add hl, hl
    add hl, hl
    add hl, hl; multiply by 32

    ld a, b
    and 00001100b; select extended slot
    sla a; times 2
    ld de, 0
    ld e, a
    add hl, de

    ld de, SLTWRK
    add hl, de

    ld a, (hl)
    ld e, a
    inc hl
    ld a, (hl)
    ld d, a
    
    ld hl, de
    or a ; clear Cy
    ret

; h = memory address high byte (bits 6-7: page)
; a <- slot ID formatted FxxxSSPP
; Modifies: f, bc, de
Memory_GetSlot:
    call BIOS_RSLREG
    bit 7,h
    jr z,PrimaryShiftContinue
    rrca
    rrca
    rrca
    rrca
PrimaryShiftContinue:
    bit 6,h
    jr z,PrimaryShiftDone
    rrca
    rrca
PrimaryShiftDone:
    and #0b00000011
    ld c,a
    ld b,#0
    ex de,hl
    ld hl,#BIOS_EXPTBL
    add hl,bc
    ld a,(hl)
    and #0x80
    or c
    ld c,a
    inc hl  ; move to SLTTBL
    inc hl
    inc hl
    inc hl
    ld a,(hl)
    ex de,hl
    bit 7,h
    jr z,SecondaryShiftContinue
    rrca
    rrca
    rrca
    rrca
SecondaryShiftContinue:
    bit 6,h
    jr nz,SecondaryShiftDone
    rlca
    rlca
SecondaryShiftDone:
    and #0b00001100
    or c
    ld l, a
    ret

Allocating more memory in page 3 leads to all kinds of compatibility problems. It's too short-sighted.

Yes, we have to balance performance with memory. I also don’t like taking more page 3 then necessary. With MSX Dos 2/Nextor there is already a lot used there. Sent by phone

…

________________________________ From: D15C0DE ***@***.***> Sent: Sunday, August 15, 2021 2:23:37 PM To: S0urceror ***@***.***> Cc: S0urceror ***@***.***>; Author ***@***.***> Subject: Re: S0urceror/sltwrk.asm @D15C0DE commented on this gist.

________________________________ Allocating more memory in page 3 leads to all kinds of compatibility problems. It's too short-sighted. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<https://gist.github.com/63ffbd58b9e58c083c12fb9b071a24d7#gistcomment-3861738>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABGC6KG25WCFKJVMLMN5UETT46WUTANCNFSM5CFEVTIQ>. Triage notifications on the go with GitHub Mobile for iOS<https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android<https://play.google.com/store/apps/details?id=com.github.android&utm_campaign=notification-email>.