03.010 How can I program the ZipGSx registers?
Description
This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
03.010 How can I program the ZipGSx registers?
ZipChip GS Special Registers Ex ZIP Technology, 12 October 1990
Registers must be unlocked before they can be accessed (see $C05A). Locking
them will re-enable the annunciators.
Writing to any I/O location $C058-$C05F (whether registers are locked or
unlocked) will reset delay in progress.
$C058 R No operation
$C058 W Write any value to force power-on/reset bit to COLD (forces
next reset to restore ZIP registers to defaults/switch settings).
$C059 R/W 76543210
....... Bank Switch Lang Card cache disable=1/enable=0?
....... Padl delay (5 ms) disable=0/enable=1 $C070/$C020
....... External delay (5 ms) disable=0/enable=1
....... Cntr delay (5 ms) disable=0/enable=1 $C02E/$C07E
....... CPS follow disable=0/enable=1
....... Last Reset warm? READ ONLY
....... Hardware DMA READ ONLY
....... non-GS (0)/GS (1) READ ONLY
$C05A R 76543210
****.... Current ZIP Speed, 0=100%, 1=93.75%,..., F=6.25%
....1111
$C05A W Write values as follows:
$5x Unlock ZIP registers (must write 4 times)
$Ax Lock ZIP registers
other Force ZIP to follow system clock (disable card)
$C05B R 76543210
....... 1msclk - clock with 1 ms period
....... cshupd - Tag data at $C05F updated
(read $C05F to reset)
....... Bank Switch Language Card cache (0), don't (1)
....... Board disable - 0=enabled, 1=disabled
....... delay in effect (0=ZIP, 1=Slow)
....... rombank (0/1) - not in development version
......** Cache RAM size (00=8k, 01=16k, 10=32k, 11=64k)
$C05B W Write any value to force ZIP to current speed
(i.e. enable card)
$C05C R/W 76543210
*******. Slot 7-1 delay enable (all slots 52-54 ms)
.......* Speaker delay enable (5 ms)
$C05D R Current 65816 bank
$C05D W 76543210
****.... Set ZIP speed, 0=100%, 1=93.75%, ..., F=6.25%
....**** Don't care
$C05E R Read last Tag data written and force the next write
to create a trash tag value.
$C05E W No operation
$C05F R Read last Tag data written and reset cshupd.
Note: apparently any write to a ZIP register
(unlocked) will clear cshupd, but cshupd
says that this location must be read.
$C05F W No operation
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