Percom RFD Disk Drives Option Table
From: by way of Michael Current (j_t_kirk@geocities.com)
Date: 05/24/99-06:02:00 PM Z
From: JTKirk <j_t_kirk@geocities.com> (by way of Michael Current)
Subject: Percom RFD Disk Drives Option Table
Date: Mon May 24 18:02:00 1999
I found the file PERCOMDD.DOC...
This file should be LISTed to a printer with the width being
set to 80 columns. This file is intended for use by anyone
with Percom double density drives who wishes to know more about
what is on the ROM chip. For furthur study of how these tables
are used, see the SAMPLE program on the diskette that is sent
with each Percom first drive system.
TM RFD 007 20 SEPTEMBER 1982
TECHNICAL MEMO
PRODUCT: RFD DISK DRIVES
SUBJECT: OPTION TABLE
Percom RFD disk drives for the Atari home computers use an
intelligent disk controller. In order to properly handle its
functions, a ROM chip containing an Option Table has been
developed. This Option Table is located in a 1K RAM chip on
the controller board, and can be accessed by request from the
computer.
Below are tables which will help the programmer in
understanding the calls on the Percom controller. Of
particular note are the bytes which handle the density of the
controller.
The Read Option and Write Option commands pertain to the 12
byte Option Table. There is one table set up for each drive.
To access these tables, see the SAMPLE program on the Percom
Software Support diskette that comes with Percom Double Density
drive systems (NOTE: included on this disk as "PERCOMSM.PLE").
==============================================================
INDIVIDUAL COMMANDS TABLE
FORMAT 21(hex) FORMAT DISKETTE
RDOPT 4E READ OPTION TABLE FOR A DRIVE (TABLE 2)
WROPT 4F WRITE OPTION TABLE FOR A DRIVE (TABLE 2)
WRSECT 50 WRITE SECTOR WITHOUT VERIFY
51 UNDEFINED
RESECT 52 READ SECTOR
RESTCM 53 READ STATUS MESSAGE (TABLE 3)
54 UNDEFINED
55 UNDEFINED
56 UNDEFINED
57 WRITE SECTOR WITH VERIFY
===============================================================
===============================================================
OPTION TABLE TABLE 2
All 2-byte values are in MSB,LSB format, unlike the 6502
practice which uses LSB,MSB format.
BYTE(S) OPTION
0 Number of tracks (This is a literal value)
1 Step Rate (Standard 17xx FDC coding)
value rate
----- ----
00 30 msecs.
01 20 msecs.
02 12 msecs.
03 06 msecs.
2,3 Sectors per track (This is a literal value)
4 Number of Sides 0= 1 side
1= 2 sides
any other values will cause unpredictable results
5 Density 00= Single Density
04= Double Density
any other values will cause unpredictable results
6,7 Sector Size (bytes per sector. This is a literal
value)
8 Drive Present 00= Drive is not present
any other value indicates a drive is present
9 ACIA not currently implemented
Bytes 10 and 11 are reserved for future expansion
==============================================================
==============================================================
DRIVE STATUS TABLE 3
BYTE USE
0 SYSTEM STATUS OF DRIVE
value status
----- ------
32(dec) sector size 0=128 1=256
16 motor on?
8 write protect
4 FDC error
2 data frame error
1 cmd frame error
1 FDC status
2 Timeout for format- How long to wait for response to
format
3 Current track where read/write head is located
==============================================================
-END-
--
__________ ____---____ Marco Antonio Checa Funcke
\_________D /-/---_----' mailto:mcheca@li.urp.edu.pe,
_H__/_/ jtkirk@usa.net,JTKirk@HoTMaiL.com
'-_____|( http://www.GeoCities.com/Hollywood/2645
-----------------------------------------
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