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apple2cp: correct a misunderstanding of the built-in accelerator's registers [R. Belmont]

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This commit is contained in:
arbee 2021-03-23 23:18:35 -04:00
parent 5bd267a7ed
commit fdc27464d7
1 changed files with 16 additions and 27 deletions
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43
src/mame/drivers/apple2e.cpp
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@ -100,12 +100,11 @@ Normal: Store $08 to $C05A (Zip compatible)
Lock: Store $A5 to $C05A (Zip compatible).
Unlock: Store $5A 4 times in a row to $C05A (Zip compatible).
Read state: Cached by the firmware in MIG RAM (see below).
Write state: Store speaker/slot byte at $C05C (NOT Zip compatible). Firmware always enables the paddle
Write state: Store speaker/slot byte at $C05C (Zip compatible). Firmware always enables the paddle
delay at $C05F, regardless of what you pass in.
For the $C05C slot/speaker delay, the Zip has bit 0 = speaker, 7-1 = slots 7-1, and 1=normal, 0=fast.
The IIc+ instead is as documented in the IIc Technical Reference Manual, Second Edition: bit 7=speaker,
bits 6-0 = slots 7-1, and 1=fast, 0=normal.
Previous versions of this driver stated that the IIc+ speaker/slot control byte was not Zip compatible; that
was a misunderstanding.
Accelerator control firmware saves/restores zero page locations 0-7 in MIG RAM page 2 locations $CE10-$CE17.
MIG RAM page 2 $CE02 is the speaker/slot bitfield and $CE03 is the paddle/accelerator bitfield.
@ -715,46 +714,39 @@ void apple2e_state::sel35_w(int sel35)
void apple2e_state::recalc_active_device()
{
// printf("recalc_active_device: devsel %d 35sel %d intdrive %d\n", m_devsel, m_35sel, m_intdrive);
if (m_devsel == 1)
{
if (!m_35sel)
{
// printf("5.25 1\n");
m_cur_floppy = m_floppy[0]->get_device();
}
else
{
// printf("3.5 1\n");
m_cur_floppy = m_floppy[2]->get_device();
m_cur_floppy = m_floppy[3]->get_device();
}
}
else if (m_devsel == 2)
{
if (!m_35sel)
// as per http://apple2.guidero.us/doku.php/mg_notes/apple_iic/mig_chip intdrive + devsel = 2 enables
// the internal drive, no 35sel is necessary. If intdrive is clear, 35sel and devsel work as normal.
if (m_intdrive)
{
m_cur_floppy = m_floppy[2]->get_device();
}
else if (!m_35sel)
{
// printf("5.25 2\n");
m_cur_floppy = m_floppy[1]->get_device();
}
else
else // should be external 3.5 #2, for a 3rd drive
{
// hookup is a little weird here
if (m_intdrive)
{
// printf("3.5 1\n");
m_cur_floppy = m_floppy[2]->get_device();
}
else
{
// printf("3.5 2\n");
m_cur_floppy = m_floppy[3]->get_device();
}
m_cur_floppy = nullptr;
}
}
else
{
m_cur_floppy = nullptr;
}
m_iicpiwm->set_floppy(m_cur_floppy);
if (m_cur_floppy)
@ -2370,9 +2362,7 @@ u8 apple2e_state::c000_iic_r(offs_t offset)
do_io(offset, true);
if ((m_accel_unlocked) && (offset == 0x5c))
{
u8 temp = (m_accel_slotspk ^ 0xff) >> 2;
temp |= (m_accel_slotspk & 1) ? 0 : 1;
return temp;
return m_accel_slotspk;
}
break;
}
@ -2504,8 +2494,7 @@ void apple2e_state::c000_iic_w(offs_t offset, u8 data)
case 0x5c:
if (m_accel_unlocked)
{
u8 temp = data ^ 0xff;
m_accel_slotspk = (temp << 1) | ((temp & 0x80) ? 1 : 0);
m_accel_slotspk = data;
}
break;