774 lines
32 KiB
Plaintext
774 lines
32 KiB
Plaintext
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[33m
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THE OBESE AGNUS,THE NEW 500 BOARD AND OTHER RECENT EXPERIENCES.
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`````````````````````````````''''''''''''''''''''''''''''''''''
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[0m
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[3m By Andrew Wilson 23/07/89.
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WARNING.. ANY MODIFICATIONS MENTIONED IN THIS ARTICLE SHOULD ONLY BE DONE
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BY TECHNICALLY COMPETENT PERSONNEL: TECHNICIANS ETC.(not
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engineers) AS REPAIRS TO THESE MACHINES ARE COSTLY AND SERIOUS
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DAMAGE EASILY DONE.THE REMOVAL OF PLCC CHIPS (A500 AGNUS) FROM
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THEIR SOCKETS WITHOUT THE PROPER TOOLS IS PARTICULARLY
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HAZARDOUS. MOST OF THESE MODIFICATIONS REQUIRE GOOD SOLDERING
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SKILLS ETC. ALL WORK SHOULD BE CARRIED OUT AT AN ANTISTATIC
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WORK STATION. STATIC DOES EXIST, IT IS NOT A FAIRY STORY PUT
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OUT BY 3M CORP. TO SELL THEIR ANTISTATIC GEAR. SEE
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ANTISTATIC WARNING ELSEWHERE IN THIS SECTION. ALL POSSIBLE
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CARE HAS BEEN TAKEN IN PREPARING THESE NOTES BUT ANY
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MODIFICATIONS ARE DONE ENTIRELY AT YOUR OWN RISK.
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All modifications stated as fact have been done by me, mods
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put up as possibilities are my thoughts on a subject and have
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not been tried.
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[0m[32m
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|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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[0m
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[Ed: Andrew is the brains behind the original Proton Ram boards,
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which are still valued very highly by their owners. He is now
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running his own Amiga-specific hardware manufacturing business
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(on a human scale, with human scale prices, too) and it may not
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be an exaggeration to say that there is little he doesn't know
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about the Amiga in general, and hardware specifically. He
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provides numerous products for all models of the Amiga,
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including 8-meg Ram boards, hard disks, digitisers, real-time
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clocks, and many other products. You'll see below that he
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really knows what he's talking about, and he's always been
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available to me when I have a hardware problem. He can be
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contacted at:
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2 Meredyth St,
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Millswood 5034.
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With the expert help of Mario Nicotra, this mod was done to my
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early (Rev. 5A) A500, and it worked fine - the business of the
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switch from NTSC to PAL screens was done by bending the socket
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of pin 41 of the Agnes chip, perhaps the easiest of the alter-
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natives mentioned by Andrew. Note also that the full details
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required are here: all the docs from the US and even from
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Commodore here tend to forget to show you how to make the change
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from NTSC to PAL...
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[32m
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|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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IN THIS INSTALLMENT
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------------------
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The Obese Agnus Chip
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Obese Agnus Software Compatibility
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Fitting the Obese Agnus to the REV5 A500 (Original 500)
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The New REV6A A500 Board
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The Different Types of A500s and Identifying Them
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[ED: 2000 Modification follows at bottom]
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[0m
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[33m
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The Obese Agnus Chip.
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---------------------[0m
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The Obese Agnus Chip (8372A or 318069-02) is the new Agnus chip capable
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of addressing 1 MegaByte of Chip Ram on the A500 or B2000. This allows
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you to have more than TWICE as many windows and screens open than is
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possible with a standard Fat Agnus equipped machine. If opening twice
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as many screens and windows isn't your thing then it also means that
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the Hi-res modes of such programs as Digiview, DeluxePaint and others
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which refuse to run until all extra drives, windows, screens are closed
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will now open and also allow you to run extra flip screens etc. Games
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such as Boulderdash/Emerald Mines which refuse to load unless all
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external drives are disconnected are now much happier as well.
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Commodore is now shipping the Obese Agnus in most of the current A500s
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(without telling anybody) although Commodore in the USA will admit to
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it when questioned. These A500s are set up in Fat Agnus Mode so that
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even if an A501 board is plugged into them no improvement is obtained
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without further internal modification.
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[33m
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Obese Agnus Software Compatibility.
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-----------------------------------[0m
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Already 1 animation package (VideoFX 3D I believe) has been found which
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will not run with the 8372A in either Fat or Obese mode. This is a
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problem caused by the programmer reading or writing to registers in the
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Agnus chip in an illegal (non-Commodore approved) manner and may
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(should) be fixed in later releases of the package. CHECK that any
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software that you HAVE to use works with ONE Meg of Chip Ram before
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committing to this upgrade. All other programs tried so far, about
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150, have been completely compatible.
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[33m
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Fitting the Obese Agnus to Early A500s.(REV5 Boards)[0m
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---------------------------------------
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Contrary to a message appearing on many local Bulletin boards it is not
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necessary to have the new Rev 6A board to fit the Obese Agnus to an
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A500. The 8372A can be fitted to the older Rev 5 boards simply by
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doing the following :
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1 Remove the Fat Agnus 8371 from its socket (see warning above).
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Check orientation of pin 1 to facilitate installation of 8372A. Pin
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41 of the Agnus socket which is earthed on all REV5 boards controls
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whether the A500 starts up in NTSC or PAL mode. When it is earthed
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the Obese Agnus initialises in NTSC Mode which means that all USA
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owners need to do is plug in the chip and they are in the correct
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mode. We on the other hand have to de-solder and remove the socket
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from the board to isolate pin 41 which is connected to earth on both
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sides of the board. This chip was designed in the USA!! Removing
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the socket is a difficult and laborious task so other methods of
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isolating pin 41 are possible. I DO NOT recommend trying to drill
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through the board as the two pins 41 and 42 are very close together,
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the trace between them is thick and there are thin tracks either side
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of it under the socket on the top of the board. Bending the contact
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on the socket is a possibility but make sure you get it right or
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you'll be removing the socket anyway. Placing a thin piece of hard
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plastic, eg mylar, between the pin and the contact is another
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possibility. By putting a SPST toggleswitch between pin 41 and earth
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it is possible to switch between NTSC and PAL on resetting the
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machine. This would give good compatibility with American software
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and for this reason and others DO NOT just break or cut pin 41 off
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the chip. Pin 41 is taken to a jumper pad on REV6A boards.
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1 1 8 8 8 8 8 7 7 7 7 7
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1 0 9 8 7 6 5 4 3 2 1 4 3 2 1 0 9 8 7 6 5
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BEVELED CORNER | | | | | | | | | | | | | | | | | | | | |
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/¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|
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12 -| ¤ |- 74
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13 -| ^ |- 73
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14 -| | |- 72
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15 -| INDENT FOR PIN 1 |- 71
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16 -| |- 70
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17 -| |- 69
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18 -| |- 68
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19 -| |- 67
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20 -| 8372A |- 66
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21 -| |- 65
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22 -| |- 64
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23 -| TOP VIEW |- 63
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24 -| |- 62
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25 -| |- 61
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26 -| |- 60
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27 -| |- 59
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28 -| |- 58
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29 -| |- 57
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30 -| |- 56
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31 -| |- 55
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32 -| |- 54
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|____________________________________________|
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| | | | | | | | | | | | | | | | | | | | |
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3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5
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3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
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2 Insert the Obese Agnus 8372A into the socket paying particular
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attention to the orientation. Pin #1 is located in the centre of the
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side immediately clockwise from the beveled corner of the chip and is
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marked by a small dimple. The 8372A should be installed with pin 1
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to the front of the socket. This is marked by a large 1 on the
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silkscreening on the circuit board just above the words "FAT AGNUS".
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I overstress this point because this is an expensive chip and a
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wrongly inserted chip which has had power applied to it probably has
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a value of 0000 dollars. The socket on the REV6A boards has been
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rotated 90 degrees anticlockwise. BE WARNED!!
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3 Locate the jumper JP2 on the circuit board to the right of the 68000
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chip. Cut the trace between the centre and lower pads carefully with
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a sharp knife. Join the centre and upper pads with a small piece of
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light wire. This jumper changes the address of the A501 board or
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equivalent from C00000H to 080000H to make it contiguous with the
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first 512K of memory to give a 1MEG block of chip ram. The three
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pads of JP2 can be wired to a SPDT toggleswitch to allow changing
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from one memory location to the other if there is any software
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incompatibility with the new setup.
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4 Pin 32 of the GARY chip (located above right of the Agnus socket)
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must be open circuit for this upgrade to work. This pin is the
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*EXRAM signal which is normally earthed by the A501 board when it is
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plugged into the A500. Several methods of achieving this are
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available as follows:
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a. If you have installed one of my A501 memory disable switches
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or other similar modification which open circuits pin 32 of the
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A501 memory expansion connector then this will serve the
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purpose. Leave it in the OFF position and disregard the rest of
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section 4.
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b. Locate the GARY chip and remove from its socket. Locate pin 32
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and CAREFULLY bend it slightly outwards so that when GARY is put
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back in its socket pin 32 does not go into its socket. Return
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the GARY chip to the socket making sure that it is correctly
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positioned ie. pin 1 and notch to the right hand side. Pin 32
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can be connected through a SPST toggleswitch to earth to
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preserve compatability with the Fat Agnus.
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Notch in end of chip
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V
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_________________
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Pin numbers > 1 -| o \_/ |- 48
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2 -| |- 47
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3 -| |- 46
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4 -| |- 45
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5 -| |- 44
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6 -| |- 43
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7 -| |- 42
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8 -| |- 41
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9 -| |- 40
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10 -| |- 39
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11 -| |- 38
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12 -| |- 37
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13 -| |- 36
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14 -| GARY |- 35
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15 -| |- 34
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16 -| 5719 |- 33
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17 -| |- 32 < Pin to be bent in 4b.
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18 -| |- 31
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19 -| |- 30
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20 -| |- 29
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21 -| |- 28
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22 -| |- 27
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23 -| |- 26
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24 -| |- 25
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-----------------
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******* ALL DUAL INLINE PACKAGE INTEGRATED CIRCUITS ARE NUMBERED IN
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THE SAME MANNER, ONLY THE NUMBER OF PINS VARIES.
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5 Check all work done in all previous stages, and if everything is
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correct connect it to power supply, mouse and monitor and turn on the
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power. If it does not boot up as normal power off immediately and
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recheck. The longer the power is switched on with a fault the
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greater the damage. Check for bent or folded pins on GARY if you
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have had him out. If you have the disk drive disconnected or wrongly
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connected it will take a lot longer before the hand and disk appear
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on the screen.
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6 Once you have booted successfully run PERFMON from the TOOLS drawer
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of the EXTRAS Disk [Ed: or PopInfo from MD11]. It should show 1MEG
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of Chip Ram and no Fast Ram on a 1MEG A500. Now try loading a
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picture, The Tiger on Megadisc 5 is most suitable, repeatedly. It
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should be possible to load more than twice as many as before (about 8
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as against 3 I think from memory).
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[33m
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The NEW REV6A 500 Board.
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------------------------[0m
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This board has been shipped by Commodore for approx. 2 to 3 months.
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The main reason for the change has been to allow Commodore to use the
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newer 1 Megabit chips and to allow for 1 megabyte of memory on the main
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board. This means that the A501 board is no longer needed if the extra
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512K is installed on the main board. Current cost of this upgrade is
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approximately $160.00 . If the Real Time Clock is needed then clock
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boards plugging into the A501 slot are available for $50-60. There is
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provision for several resistor packs on the board although they are not
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fitted and their use is not clear. The change has little to do with
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the Obese Agnus upgrade although it is a little easier to fit to a
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REV6A board. The board also contains several new jumper pads, details
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of which are given below.
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REV5 BOARD REV6A BOARD APPARENT USE
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JP1 Yes Yes Connects 555 reset timer to main reset
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JP2 yes yes Maps A501 @ C00000 or 080000
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JP3 yes yes Swaps *CAS of 512k banks of RAM
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JP4 no yes PAL or NTSC via pin 41 of Obese AGNUS
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JP5 no yes 28MHz CLK, XCLK and XCLKEN to AGNUS
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JP6 no yes 7MHz clock on pin 7 of 86way Exp Connector
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JP7A no yes Controls *EXRAM to GARY
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JP7B no yes CIA TICK from VSYNC or pin 32 of A501
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JP8 no yes LPEN from FIRE0 or FIRE1
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JP9 no no?
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J910A no yes Connects AUDIN to pin 18 of RS232 Port
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JP10B no yes Connects AUDOUT to pin 11 of RS232 Port
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JP11 no yes Connects CSYNC to BCSYNC or Video Hybrid
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(A Week Later)
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As can be seen from the above table most of these new jumpers are for
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convenience and do not represent radical improvements over the previous
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board.
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Conversion of a REV6A board to work with Obese Agnus is fairly simply
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and will be covered in a later article which will also cover fitting
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the extra 512K of RAM to the main board.
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[33m
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The Different Types of A500s and Identifying Them.
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---------------------------------------------------[0m
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This section does not attempt to identify the different types of disk
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drives, keyboards etc. which, particularly in the case of the A500,
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seem to change almost weekly.
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The A500.
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The base model of the range which, contrary to what B2000
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salesman say, is expandable to Approx. 15 Meg of RAM, Hard
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Drives, etc. Somewhat limited power supply so a larger one is
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needed for hard drives.
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There are two basic types :
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A. The original REV5 board supplied from the beginning up until
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early 1989. Requires the A501 Board or equivalent for
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expansion to 1 Meg and use of Obese Agnus.
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B. The new REV6A board supplied from April/May 1989 on. The way to
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recognise it is to check the expansion bus connector on the
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left hand side of the computer. You'll notice that the early
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model A500 has a "fat finger" metal strip at the back end of
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the connector - the new A500 doesn't, instead it has two thin
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"fingers", ie, 2 metal strips in the corresponding place, of
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the same width as the rest of the strips of the connector.
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More on this and other related matters in the next issue.
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2000 MODIFICATION
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Ed: The modification for the A2000 is pretty similar, and has been
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done by Mario (mentioned above) on a very souped-up system. Keeping
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in mind all the warnings and hints above, it goes like this:
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A. Remove computer cover, floppy cable (noting position of the red
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wire on the cable), power plug from connectror CN400, and power
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supply and drive assembly from the main unit.
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B. Remove the old slimmer Agnes as above, preferably using a chip
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extractor. Insert the new chip with the right alignment.
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C. Find Jumper J101 located on the lower right side of the power
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connector CN400, and consists of 3 posts - 2 of the posts are
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shorted together using a shorting block. Remove the shorting block
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and move it to the left, towards the power connector. For further
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info, see Page 13 of the A2000 system schematics - this jumper
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will enable address line 19 from the 68000 which controls the 1
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meg address range.
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D. Locate and cut Jumper pad J500 (to the lower left of the 8520 at
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U301). This is a 2-pad jumper with a trace connecting the two
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pads. See Page 9 of the A2000 system schematics - cutting this
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trace keeps the _EXRAM signal from being tied to ground.
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E. Finally, to enable PAL rather than NTSC - locate and cut J102,
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NOT J201 as suggested in some docs. This is the equivalent of
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bending pin 41 of Agnes in the A500 mod.
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The mod is now finished, so re-assemble the unit, power up and
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hope for the best! And don't attempt it unless, as mentioned
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above, you're very adept at electronics hacking. Show these docs
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to such a person, however, and there should be little difficulty.
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[32m
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|||||||||||||||||||||||||| END OF ONE_MEG_AGNES ||||||||||||||||||||
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[0m
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[43m[32m SAVING DF0: - BOOT UP FROM DF1: [0m
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by[3m Les Ayling[0m
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[32m
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[0m
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Several of my friends who are Amiga owners have had problems with the
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internal drive. This modification will overcome that problem by
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allowing Amiga 500 owners to boot from df1:.
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This mod is also useful for people who own the Commodore 5 1/4 inch
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drives and wish to boot from them. More importantly, people who have
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added an 80trk 5 1/4 inch drive (such as myself) as described in the
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file ADD_5.25_DRIVE can boot from it. As 5 1/4 inch disks can be
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bought for as low as $5.95 for 10 in some places, it is well worth
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considering as a cheap backup library option OR indeed as an
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alternative primary storage medium.
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You will need the following tools and parts:
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* Low wattage soldering iron, suitable for PCB's
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* DPDT switch mini toggle variety is fine
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* 1 foot of ribbon cable
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* solder
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* small snippers
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* hand drill
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* tool to unscrew the @#$%^& non-standard case screws
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* Exacto knife or similar
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Start by unscrewing the 6 hex style screws around the edge of the
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case (Goodbye warranty!). Do not remove the three phillips screws as
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they are holding the drive in place. Turn the machine back the right
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way up and remove the lid by pressing around the edge to ease off the
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catches. Remove the keyboard making careful note of the orientation of
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the connector on the main board!!!!! Now remove the further 4 hex
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screws which are holding the top rf shield in place and remove the
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shield. Unplug the disk drive POWER cable from the drive end only.
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Remove the 34-way disk drive patch lead taking note of its orientation
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(This saves so much time when you have forgotten later on!) Unscrew
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the Disk drive unit and remove it.
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The main PC board should now come free with the lower RF shield.
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Unscrew the hexagonal socket retainers on the I/O connectors at the
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rear of the board and this shield should come free.
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You are now ready to start!
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Locate connector 11 (CN11) on the component side, this is the socket
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that you just unplugged the disk drive patch lead from. In front of it
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should be U8 which is an 8520 chip.
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CN11 is 2 rows of 34 pins.Count along the front row from the right
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hand side until you see the 5th and 6th pins (pins 9 and 11 of the
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connector respectively). There should be two circuit traces that lead
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from these pins and disappear under U8. Using the exacto knife cut
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both of these traces leaving no stray copper. A 1mm cut should be
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sufficient.
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Turn the board over to the solder side.
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Leave the board for a moment and get the DPDT switch.
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For ease I will label its pins as such:
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A B
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C D
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E F
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Cut a piece of ribbon cable about 1' long with 4 conductors.
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Strip and tin the wires then connect them to A, B, C and D.
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Cut two small pieces of wire and connect A-F and E-B.
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|
Tin and strip the other ends of the ribbon cable.Using the snippers
|
|
trim these tinned ends until there is about 1 1/2 to 2mm showing. Any
|
|
longer is unnecessary and can lead to solder blobs etc.
|
|
|
|
Grab the Amiga pc board again. On the solder side locate pins 9 and
|
|
11 of CN11 as described earlier. Solder the lead from A to pin 9 and
|
|
the lead from B to pin 11.
|
|
|
|
Locate pins 13 and 14 of U8.
|
|
|
|
If you are unsure of pin numbering on IC's refer to one of the data
|
|
sections of DSE's or ROD Irving catalogues. Otherwise looking at the
|
|
chip there is a notch at the right hand end of the board. Pin 1 is
|
|
behind this notch (relative to the pc board) and the numbers increase
|
|
in an anti-clockwise fashion around the chip. Solder the lead from C
|
|
to pin 13 of U8 and the lead from D to pin 14 of U8. That completes
|
|
the soldering side of things.
|
|
|
|
All that remains is to drill a hole for the switch and put the rest
|
|
back together. There is a convenient spot to the right of the joystick
|
|
socket that will house 3 or 4 switches comfortably.
|
|
|
|
PLEASE PLEASE PLEASE be careful of the orientation of the connectors
|
|
when assembling your amiga.
|
|
|
|
To use the mod:
|
|
1. Remove ALL disks from ALL drives.
|
|
2. Flick the switch to the NORMAL position.
|
|
3. Turn the machine ON or reset if already ON.
|
|
4. If you wish to boot from drive DF1: now is the time to
|
|
flick the switch to the NON-standard position.
|
|
5. Insert the appropriate disks in the appropriate drives.
|
|
|
|
HOW it works.
|
|
The mod works by switching the drive select lines SEL_0 and SEL_1.
|
|
SIMPLE!
|
|
[33m
|
|
IMPORTANT:!![0m
|
|
The switch must be in the NORMAL position when you either turn the
|
|
machine on or reset.The reason for this is that after a cold or warm
|
|
boot the KERNEL roms go looking for what equipment is connected to the
|
|
system. A part of the GARY chip which is triggered by the SEL_0 signal
|
|
provides seperate MOTOR_ON signals for the internal and external
|
|
drives. When the switch is in the ALTERED position the GARY chip is
|
|
fed by the SEL_1 signal and surprise surprise! the KERNEL roms won't
|
|
find the internal drive! However is is PERFECTLY safe to change the
|
|
switch at ANY time the power is on (without disks in the drives!). So
|
|
if the switch is changed after the roms have found what drives are
|
|
online, the drives 0 and 1 will operate fine only reversed. More
|
|
circuitry could have been added to swap the motor_on signals so that
|
|
this extra switching wasn't required, however most people would
|
|
probably like to keep their mods to the main pcb to a MINIMUM!
|
|
[33m
|
|
*NOTE*[0m
|
|
If the switch is changed while disks are inserted in the drives,
|
|
AmigaDOS will become confused as to what volumes are on line and if
|
|
your write-protect tags are OFF, chances are your directories will be
|
|
CLOBBERED!!
|
|
|
|
The mod is relatively simple, however if you are unsure of your
|
|
ability to perform it.. DON'T. get some hardware oriented person to
|
|
help or drop me a line at PARAGON bbs if in Sydney, or via Megadisc and
|
|
I may be able to help or do it for you at a small nominal cost.
|
|
Naturally I cannot guarantee your labour content so therefore I cannot
|
|
make any warranties, implied or otherwise, as to the suitability or
|
|
performance of this modification. However I can say that I am not too
|
|
worried about my software collection as I have a set of bootable 5 1/4"
|
|
backups!!
|
|
|
|
Good luck and I hope that this is of some help.
|
|
|
|
[32m
|
|
||||||||||||||||||||||| END OF BOOT_FROM_DF1 ||||||||||||||||||||||||
|
|
[0m
|
|
|
|
|
|
|
|
AUDIO BOOST ON THE AMIGA 500
|
|
----------------------------------------------------------------------------
|
|
This hardware hack is not advanced and gives you a much higher volume out
|
|
of your Amiga (With good quality!)
|
|
|
|
First remove the screws (This will destroy your warrenty!) from the Amiga
|
|
shell (even the screws for the drive!) now carefully open your Amiga,
|
|
There are some pigs holding the shell at it's place so don't break those!
|
|
(as i have!) Now remove the screws from the metallic shield and gently
|
|
remove the keyboard cable! (Remember the direction the connector are!)
|
|
now remove the drive! (Yet another time remember how it was connected!)
|
|
now find the filter (LF347) near this circuit you find the condensators
|
|
at 22uF (you will actually find two!) the condensators are named C334 and
|
|
C324 and two resitors named R334 and R324 now take a dual switch and connect
|
|
it like this:
|
|
|
|
SWITCH:
|
|
|
|
+------------1 4------+
|
|
| |
|
|
| +----------2 5----+ |
|
|
| | | |
|
|
| | 3 6 | |
|
|
| | | |
|
|
| | | |
|
|
| + +C334 | + +C324
|
|
+-- R334 |
|
|
+ R324
|
|
|
|
And now you can boost more sound of ya Amiga, but be carefull you can
|
|
destroy
|
|
your speekers if ya pump up the volume too much!
|
|
(The level meter on my gettoblaster goes to max if i turn on my boost)
|
|
|
|
I must say that if your Amiga brakes down cause of this little hardware hack
|
|
then don't blame me!
|
|
|
|
And if you are not good at soldering then let someone else do it! (even if
|
|
the soldering on this hack is really easy!) and DON'T USE A HIGH WATTAGE
|
|
SOLDER IRON! (MAX 25 WATT)
|
|
|
|
Chucky of Sargon
|
|
PAUSE ON THE 68000
|
|
-------------------------------------------------------------------------
|
|
This hack works on all computers with a Motorola 68000 processor!
|
|
(Amiga, Mac, Atari) Well i will describe it as it's on the Amiga!
|
|
|
|
First remove the shell! (Ya warrenty will go to hell) find the processor
|
|
(On the Amiga 500 it's located at the left side, On the 1000 it's on the
|
|
right side, I don't know where it's on the 2000!) solder a wire on pin 17
|
|
|
|
|
|
The notch means that the pin 1 is on this side
|
|
(start to count from the little dot!)
|
|
|
|
+--_--+
|
|
1 -|. |-64
|
|
2 -| |-63
|
|
3 -| M |-62
|
|
4 -| O |-61
|
|
5 -| T |-60
|
|
6 -| O |-59
|
|
7 -| R |-58
|
|
8 -| O |-57
|
|
9 -| L |-56
|
|
10-| A |-55
|
|
11-| |-54
|
|
12-| 6 |-53
|
|
13-| 8 |-52
|
|
14-| 0 |-51
|
|
15-| 0 |-50
|
|
16-| 0 |-49
|
|
+--- 17-| |-48
|
|
|
|
|
| ETC.
|
|
|
|
|
|
|
|
| SWITCH:
|
|
|
|
|
+-------1
|
|
|
|
2-------- TO GROUND (THE METALLIC SHELL IS A GOOD GROUND)
|
|
|
|
3
|
|
|
|
|
|
|
|
Thats it! It's not dangerous to pause the computer as some guys thinks
|
|
Even if it can look strange sometimes (even crash sometimes) but that
|
|
depends how the programmer have done some things! (like showing bitmaps
|
|
and so on!)
|
|
|
|
The DMA is not stopped with this pause so for example sounds and copperlist
|
|
will go on on the Amiga (not musics like soundtracker then just the sounds
|
|
will go on but no new will come cause it's a little program but the
|
|
processor is halted so no new data will come!)
|
|
|
|
This feature can be good if you reads for example a scrolltext and the
|
|
phone is ringing then you just have to pause or if you want to check
|
|
how some guys have made some effects in a proggy
|
|
|
|
If you are not good at soldering let someone who is good to solder in your
|
|
computer!
|
|
|
|
AND DON'T USE A SOLDER IRON WITH A HIGHER WATTAGE OF 25 WATT!!!
|
|
|
|
Chucky of Sargon
|
|
|
|
|
|
|
|
[42m[33m HOOKING A 5.25" DRIVE TO YOUR AMIGA [0m
|
|
|
|
by[3m Les Ayling[0m
|
|
[32m
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
[0m
|
|
Hooking up a standard 80 track, double-sided, 5 1/4" floppy disk drive
|
|
as drive df2: or df3:
|
|
|
|
Looking at the connector from the back side of the external drive, the
|
|
pin out is as follows:
|
|
|
|
|
|
712 11 10 9 8 7 6 5 4 3 2 1
|
|
|
|
|
|
23 22 21 20 19 18 17 16 15 14 13
|
|
|
|
|
|
34 Pin edge connector pin-out is as follows:
|
|
|
|
|
|
34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2
|
|
|
|
|
|
33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1
|
|
|
|
|
|
|
|
Wire a DB25 (RS-232) connector with pins 13 and 25 cut off per the
|
|
following configuration:
|
|
|
|
|
|
34 Pin 23 Pin
|
|
|
|
-----------------
|
|
|
|
34 --------- 1
|
|
|
|
32 --------- 13
|
|
|
|
30 --------- 2
|
|
|
|
28 --------- 14
|
|
|
|
26 --------- 15
|
|
|
|
24 ---7---- 16
|
|
|
|
22 --------- 17
|
|
|
|
20 --------- 18
|
|
|
|
18 --------- 19
|
|
|
|
16 ---------
|
|
|
|
14 --------- 9
|
|
|
|
12 --------- 21
|
|
|
|
10 -- tie to ground, keep the motor running all the time
|
|
|
|
8 --------- 22
|
|
|
|
6 --------- 20
|
|
|
|
4 ---------
|
|
|
|
2 ---------
|
|
|
|
all odd numbered pins of the 34 pin connector should be tied to pins
|
|
3, 4, 5, 6 & 7 of the 23 Pin connector (grounds).
|
|
|
|
|
|
In addition, pin 11 of the 23 pin connector should be wired to a
|
|
momentary push-button that can be activated whenever a diskette is
|
|
removed and replaced with another. This tells the DOS that a different
|
|
diskette has been inserted into the drive. Simply change the diskette,
|
|
push the button and hold until DOS accesses the drives. The switch may
|
|
then be released. This function is necessary due to the fact that the
|
|
DOS seems to read the directory of the current diskette into ram, and
|
|
unless the DOS is told of another diskette being used, it will either
|
|
ask you to replace the diskette that was in the drive or write to the
|
|
diskette using parameters from the previous disk. This, of course, is
|
|
very undesirable.
|
|
|
|
|
|
Also, note that the drive must be connected when booting DOS or it
|
|
will not be noted as being on-line. The diskette does not have to be
|
|
inserted, just the drive plugged in.
|
|
|
|
|
|
Do not make any connections to the 23 pin connector, pins 23 or pin
|
|
12. These pins provide power to the Amiga drive 1 and may not be used
|
|
to power an external 5 1/4" drive. An external power supply must be
|
|
used.
|
|
|
|
|
|
The 5 1/4" drive selection header may be programmed as drive for drive
|
|
2. Drive 1 selects as DF2: and drive 2 selects as DF3:.
|
|
|
|
|
|
A motor on latch circuit may be built to eliminate the motor
|
|
continuously turning, however, the way indicated above is the quickest
|
|
and simplest method to get another drive on-line.
|
|
|
|
|
|
After this procedure is completed, the 5 1/4" drive may be used just
|
|
as any normal Amiga drive.
|
|
|
|
|
|
Considering the $295.00 list price of the Amiga drives, versus about
|
|
$50 dollar price of 5 1/4" drives, it's a real bargain.
|
|
|
|
|
|
*** As always, with any hardware project -
|
|
(1) - if you are not sure of what I am talking about, get
|
|
knowledgeable help and
|
|
(2) - TRIPLE CHECK your work before plugging in the new drive.
|
|
|
|
|
|
[32m
|
|
|||||||||||||||||||||||| END OF ADD_5.25_DRIVE ||||||||||||||||||||||
|
|
[0m
|
|
|
|
|
|
work before plugging in the new drive.
|
|
|
|
|
|
[32m
|
|
|||||||||||||| |