Zenith H-100 - Page 39

10-82
DSI
HEATH
SOFTWARE DEFINED
HARDWARE
DEFINED
Section
Definition
Section
Defi niti on
0
This bit determines 0
Status port
bit ll.
the TPI of the 5-1/11"
disk drive.
1
Status port bit
3.
o = 118 TPI.
2
Not used.
Leave at
O.
1
= 96 TPI.
3-4-5-6-7
Port addressing (HSB).
1
This bit determines
whether precomp is
on or off.
o = precomp off.
1 = precomp on.
2
Not used.
3-4-5-6-7 Port addressing.
The H-207 occupies a block of eight contiguous I/O port
addresses. The three low-order bits in this block select
1797 registers, the control latch, or the status port.
The H/Z-100 computer series place the H-207 at port address
BOH. A map of the I/O port is shown below.
I/O ADDR.
(Binary)
JlEAD
WRITE
PORT DESIGNATION
SSSSSOOO·
•
1797 Status Register
SSSSSOOO
•
1797 Command Register
SSSSS001
•
•
1797 Track Register
SSSSS010
•
•
1797 Sector Register
SSSSS011
•
•
1797 Data Register
SSSSS100
•
Control Latch
SSSSS101
•
-Status Port
• S dip switch bit
The dip switch bits are simply defined from the binary
equi val ent of the swi tches. For exqrnple, the port address
for the HIZ-100 is shown below.
SSSSSXXX** = 10110XXX = Port BO - B7.
** X = 1797 register, control latch, or status port.
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