erk@americ.UUCP (Erick Parsons) (09/19/89)
I've noticed a lot of help me messages on the board lately and can sympathize
with the poor person that loses use of his machine due to a shortage of
that magic smoke that holds silicon chips together soooo....
For those of you that don't have access to a descent BBS here is something
that I found on one of our local boards that looks VERY useful. I took this
file printed it out and filed it so's that if and when my beloved machine
should stop ticking I could fall back on this... Looks good to me :-)
--------------------------------cut here------------------------------
THE FLAKE REPORT
"Flaky" (July 15, 1989) Hacker's slang as meaning:
1. Erratic and/or unpredictable behavior or experience
2. Sometimes it works; sometimes it don't
3. Primary cause of the following auditory spasms:
a. "ARGH!!!!"
b. "AH XXXX..."
c. "#@&$!"
d. "I need a career change; marketing!"
Usage: "He's getting FLAKY..."
Means: "RUN! HIDE!"
A Bruce's Repair quote:
"If it works; it won't."
Ok folks, I'm compiling a list of what has caused flaky operation of the
Amiga computers. This is a very unpopular subject with Amiga worshippers,
but it should be one to pay particular attention since it can harm any
product faster than obsolescence and DOES cause untold user-hours of
frustrations. Flakiness affects everyone and everything from product
development to end-users and especially service. If you can add some more
to this list, you can give me a call at (415) 525-6973 and ask for Bruce.
I'm busy most of the week so the best time is on Sundays in the morning. If
you don't mind listenning to a morning grouch call any other morning.
In particular is a problem of poorly designed, slow-to-access RAM boards.
This can be especially prominent with fast expansion devices like hard
drives and frame grabbers. Number one on the list of bad boards are all
those RAM boards with 150 nano-second RAMs. This is the time it takes the
RAM to access valid data. The smaller this number the better.
There are a lot of Amigas that need modifications. Starting with the
A1000's, the daughter board needs to have its PAL chips wired together to
the mother board ground and a wire to the expansion bus to the power supply
ground connector. In worst cases, two of the PAL chips must be replaced
with faster one's. The best source of PALs has been from Spirit
Technologies. The A2000's needed to have the keyboard data and clock line
capacitors removed. All the Eltek power supplies needed to be checked that
a .01 MFD capacitor was installed across R65 to suppress noise and a "00"
with a line through it written on the power supply label. The buffer chips
U605 and U602 should be 74ALS245 and not the slower 74LS245. A 3300 ohm
resistor should be installed between pin #20 and pin #11 on chip U605's
address strobe. The Gary chip has been fixed to allow processor access to
the KickRoms and expansion devices without needless co-processor
contention. (The MOS Gary) The A500 especially needed a piece of cardboard
placed behind the keyboard to prevent the keyboard from shorting to the
mother board metal shielding. An authorized transistor kludge must be
installed on all but the most recent A500's to clean up a signal from the
Gary chip. The biggest flake generator was and still is the metal shielding
on the A500. The main metal shielding had a lip just behind the internal
disk drive (i.e just left of the drive as you face the computer) which does
cause shorts at the end of the drive ribbon cable. The solution is to bend
the lip under the shielding or to put electrical tap over the edge of the
lip.
Much can be said about poorly written programs. We've all suffered as
unpaid and unwilling "beta testers" from companies lacking in product
quality. If it works on their machine, it does not necessarily mean that it
will work on all Amigas because of hardware, software, update, and user
differences. Sometimes they listen to the problems; sometimes they ignore
or pacify us with promises, good-will, and just pure charm. Worst case is
the buck passing. Badly written programs can go wild and corrupt our system
and even ruin DOS file structures. It can be as subtle as corrupting a
single bit, presently unused, to wiping out an entire system. Programs can
at times work with no apparent trouble until it's discovered later in time.
This can lead to blaming the wrong program or hardware as the cause of the
problems. This will sound very cynical but don't believe ANY review or even
this report of mine. (sigh..) Just take it with a grain of salt. Look over
people's shoulders, get the dealers to demonstrate their wares, stop by a
free-form users group and judge for yourself. Seek-out end-users of a
product. Get to know the modem community of Amiga users. Report problems to
the people responsible for the product if you think you've found a
consistent problem. Unfortunately, flaky problems are not easily repeatable
nor consistent, so it may be hard for them to justify their time to prove,
find, and solve the problem beyond a symptom.
Static electricity, even when we don't feel or hear the "tingle", can make
computer chips flaky. Always touch the power supply case before even
getting close to any circuit board or chip. In the situation of the A500,
touch the internal disk drive case. A lot of damage has been caused by
AGNUS chip installations. CBM has packaged the computer chips without
anti-static material and the retailer many times have not Xeroxed the
installation instructions for the customers. Topping the list of user
burn-outs is improper cable connections or installation. If you can't bet
your wallet, don't do it. I'd say a fair retailer AGNUS installation charge
should be around $20-$25.
Degrees of unfamiliarity with the equipment or the system can cause
unpredictable results. I shutter at the thought of what I would do to my
present system if I was a new user and not able to access all the books,
documentation, experience, and lastly my fellow computists. An old problem
with books, documentation, and advice is that a certain level of background
knowledge is expected and assumptions about your system are made from all
sides of communication. The learning process is a leap frogging of books,
notes, magazines, practice, and many times just pure inquisitive hands-on
hacking.
Never assume a computer cable is correct if it fits. There are unending
variations of cables with the same connectors on the ends. Once you've
found the purpose and correct cable, it's best to label the connector ends
with where they go. It's always good to have a continuity checker and
documentation of the pin assignments. The wrong cable can and does burnout
computers. Worst case is if it becomes flaky.
Ok, the following is are extracts from my notes and take it with a grain of
salt for flavoring. Be careful, because it is in a raw state and reaching a
conclusion from the notes will have to be tested for other machines.
UNSKILLED AND UNKNOWLEDGEABLE ATTEMPTS AT REPAIR OR MAINTENANCE CAN BE
EXTREMELY DANGEROUS AND SHOULD BE LEFT TO QUALIFIED TECHNICIANS ONLY.
UNAUTHORIZED SERVICE VOIDS YOUR WARRENTY.
All monitors
1) Re-solder HV coil to main board
2) Clean off dust and oil
3) Check for burnt or heated spots
1084 monitor (very similar to 1902A)
1) Intermittents
a) Cold solder joints and broken traces especially around
daughter boards and HV coil and leads
2) VERY INTERMITTENT "snap!" of video; audibly noticeable.
1084S-Philips (very similar to 1902A)
1) Nothing
a) bad R475 (15K 2w flame) damaged from bad C476 (.047uF, 250V)
and T402. Between June 88 and Sept 88 require warranty repair.
1084S-P monitor repair kit PN# 314891-01 billed $44 and credited
when T402 is returned to parts depot with NARDA form.
1902/2002 monitor
1) Fuse blower
a) defective degaussing switch (TH501)
b) defective voltage regulator STR30123 (IC501)
A500
1) no mouse movements
a) replace burnt EMI401 (1.0 ohm 1/4 watt resistor)
2) flaky computer
a) do the 2N3906 kludge
b) check main computer shield shorting behind disk drive
c) Check solder joints on power socket
d) flaky internal disk drive power cord
e) check for bent chip pins and for bent connector pins
f) check keyboard assembly for flakes
3) Power Supply (PN 312503-05)
a) pin1 +5V 4.5A
b) pin2 shield gnd __ __
c) pin3 +12V 1A |3 \/4 |
d) pin4 signal gnd | 5 | Looking into the plug end
e) pin5 -12V .1A |2___1_|
4) Green Screen; 10 short 1 long power LED blink
a) clean and re-insert Agnus chip
5) flaky keyboard assembly with spurious characters or crash with
CAPLOCK LED blink
a) replace keyboard and tell customer of possiblity of a serial
device being connected to the parallel connector
A1000
1) fast steady power LED blink; dark screen
a) 74S51 (U9I) & 74F74 (U8I); Damaged from expansion port
2) no parallel output
a) 8520
b) PAULA
3) Goes thru diagnostic blinks but no Kick icon
a) Check for internal disk drive "track-zeroing" movement
4) Dead
a) check that expansion shield fingers aren't bent to mother
board
5) Check for bent connector pins
6) no serial
a) check MC1488 & MC1489
b) check PAULA
7) Bad mouse or joy stick movements
a) check 74LS157
b) check 8520's
A2000 (see also A500 & A1000 & A2500 for hints)
1) Red screen; power LED blinks 9 short 1 long continuously
a) bad ram with open
2) Dark blank screen on power-up; LED dim
a) BUSTER
3) System time erratic
a) check for noise on TICK line; CBM modification to power supply
4) Bad mouse movements
a) 8520
b) clean mouse
c) broken wires in mouse cord
d) bad 74LS157 (U202)
5) First character from keyboard missing after power-up
a) cut out C910 & C911; CBM modification
6) Fuzzy video
a) remove a turn from the ferrite beads on the RGB lines
7) White screen; no Workbench Icon; LED bright
a) No power to PAULA; R200 (1 ohm resistor) burnt
8) intermittent guru's
a) Bad contacts on BridgeBoard (card edge or chips or bus-timing)
b) Virus use KV and Sentry program
c) Bad program(s)
d) Bad ram expansion board with flaky 150ns ram (should be
100ns);
AMIGA 25000 (twenty-five thousand) 2MEG board is FLAKY
e) use TestMem by Bruce's repair to find bad bits
f) CHECK THE CLOCK SIGNALS with scope for proper voltage levels
9) No Red in RGB only (new unit)
a) bad solder joint or bad trace under board at RGB connector
10) Check for bent connector pins
11) No Serial Port
a) DTR always on
1) replace MC1488 &/| MC1489
2) bad U301 CIA
3) bad PAULA
12) Modifications:
a) Replace U602 and U605 (74LS245) with 74ALS245
Make sure that 74XX24(4|5)'s between Agnus & Ram are F types
the symptoms include spots appearing on screen
b) Cut-out C910 and C911
c) Put noise by-pass cap (.01ufd) on ElTek power supply TICK line
across R65.
d) Check for proper usage of ferrite beads at video connector
e) put 3300 ohm resistor between #20 & #11 of U605
f) Read TechTopics Issue #25 Section #3 (Apr-May-Jun 89) for details
1) remove R901, C917, C902, C910, C911, C905, C908, C230, C240
2) replace 1.2 KickRom with 1.3 or latest version
3) if U205 & U206 are 74HC244 install RP904, RP905, RP906
(4.7Kx5); if they are not DON'T install (e.g. 74HCT244)
4) add .01 UFD cap on J300 center connector to ground pad
5) add 470 ohm resistor to D800 cathode to second pad from the
left, under CN605. 4.3 rev boards and up have R1000 left of Q302
instead.
6) if R5719 installed, add 470 ohm resistor between VCC and CPU
side of R106.
7) Replace ALL Gary chips (5719) with MOS type p.n. 318072-01
8) Install new reset chip MITSUMI PST518B into ALL rev 6 boards
(see TechTopics 25/3-3.1)
13) Bad joy stick moves
a) U202 (74LS157)
14) Garbage from printer port
a) bad U300 CIA
A2500 (see also A2000 for hints)
1) Put 3.3k ohm pull-up resistors on pin 11, 12, 13, and 14 on U605
These are buffered AS, UDS, LDS, and R/W signals for the
expansion
A2XXX Power Supply
1) check diodes and all semiconductors with digital IC-safe ohmmeter
2) use variable transformer to bring AC voltage to operation
3) use 25ohm 10 watt resistor on 5v+ main to load for testing
Amiga Disk Drives
1) Clean with Q-tips and alcohol
a) if heads are sticky when they touch each other, clean heads
with "KESTER Rosin Residue Remover".
2) "TICK-TICK" (5 ticks/sec noise with spinning disk in drive)
a) after cleaning head and spindle, try lightening the pressure
of the head spring (problem especially with #? drives)
3) Works fine when connected as an Amiga Drive but not when
connected to a PC Bridgeboard.
a) Replace the 74LS38 with a 7438 chip.
4) intermittent operation
a) Broken wires in cable; check daughter board interconnects
b) cracked magnetic glass switches
c) Magnetic interference: rotate drive 90 degrees & recheck
d) Motor spin erratic (on-off); re-solder motor board
1) for Matsushita Drives, surface mount chip located between
the drive frame and motor board and behind the eject button
has bad contact; wedge with spacer
5) Head "plays like a violin" on the disk
a) clean head with rosin remover
6) If a cardboard drive protector is used, check drive head mounts
and angles. Advise user of the danger of using head protectors
from another drive and the possibility of damage to heads with
worn protectors bending the head mount springs.
7) If dogs and cats are within fur range, blow into drive openning.
Hard Drive Controllers
1) check voltages & cables
2) check bus buffer chips
3) check daughter board interconnects
A-Live Board (for A500)
1) With time (hours and moon phase) D#aint## will be missing pixels
from its picture when loaded; reloading the same picture with D#####
will eventually bring back all the missing pixels! This problem
happens when the S#### Harddrive is connected between the A-Live and
the A500. Other symptoms include the volume names to WorkBench
Screen get corrupted but can be read with the INFO command without
error!
) UNSOLVED MYSTERY!!
a) Gary chip revision? (How do I get the latest version...)
b) Power Supply voltage too low? Too high?
c) Bus over-load?
d) Needs bus termination?
e) Needs F, ALS, or HC type chips buffering between video RAM &
Agnus?
AMIGA RAM BOARDS
1) A1000 Spirit board
a) interconnects broken on Spirit Ram Board
b) check for correct shorting blocks and wiring
2) Remove and replace 150NS boards with faster ones.
3) Use Bruce's TestMem to find bad chips
Amiga Repair paths:
A) Get customer to relate what activity was occurring before
the onset of the problem.
B) Color of Screen and activity of LEDs
1) Dark screen LED dead or blinking quickly
a) Check power supply and TICK line
b) Check ALL clocks
c) Check power on each individual chip
Tips:
1) Bad RAM with an internal OPEN circuit can be checked by
"piggy-backing" the ram chip with the same type of RAM
2) Bad RAM with an internal SHORT circuit can be hotter to the touch
than the rest of the RAMs
3) Improper removal of chips from sockets with a screwdriver can cut
circuit traces under the chip; always check under chips and for
damaged socket connections.
5) For the A2000-A2500, put four 3.3K ohm pull up resistors on U605
(74ALS245)
a) pin11 to pin20; pin12 to pin20; pin13 to pin20; pin14 to pin20
Tips for Smooth Operation of the Amigas
by Bryce Nesbitt & Bruce Takahashi
(previously written a couple of years ago)
1) For the Amiga A1000, connect the pin #10's (ground) of the four PAL's
together on the daughter board with heavy wire. Apparently the signal
ground path is strange and creates unreliable logic signals to U6J, U6K,
U6L, and U6N. If you want a better connection, wire the mother board and
daughter board grounds together.
2) Check the expansion hold-down screws for proper length (not too long)
Sometimes the screw will bend and short the second of the two layers of
sheet metal to the circuit board. It may be best to try and first set the
screws without the video expansion ram to "pre-tap" the sheet metal. It
will be easier then to snug the hold-down screws for the expansion card.
3) Push all chips down fully into sockets. Some chips may not be seated
properly or even have bent pins. Straighten bent chip pins with a pair of
smooth pliers.
4) Preferences has a screen centering gadget that if moved too far to the
left, will cause some of the sprites to be distorted.
5) For programmers:
a) Use this instead of AllocMem():
#include "exec/memory.h"
/* Safe AllocMem. Will not let your run the system down to zero bytes.
* For all to use, by Bryce Nesbitt
*
* You may wish to increase PANIC_FACTOR.
*/
#define PANIC_FACTOR_CHIP 4096L
APTR SafeAllocMem(size,flags)
long size;
long flags;
{
register APTR p;
if ( p=(APTR)AllocMem(size, flags) ) {
if ( AvailMem(MEMF_CHIP) < PANIC_FACTOR_CHIP ) {
FreeMem(p,size);
return(0);
} /* System is low... no go! */
}
return(p);
}
If you need to tell the user that the system is out of memory, but there
is not enough memory to post a requester or Alert, simply set the title of
your Window or Screen to "** NO MEMORY **" (possibly with a red pen
color). This operation does not require any allocations. b) There is a bug
in Text() that will clip text too soon if the write is started from beyond
the left edge of the RastPort. c) WindowToFront() (and probably the other
Intuition "deferred" actions) will lock up if the user is holding down an
icon from the Workbench tool.
6) If you use internal memory expansion, you should ground clip the
motherboard to the internal expansion board, preferably at the point on
the expansion were the ram array is.
7) Use only high quality disks. Poor disks may format and copy correctly
but time may find lost data or files.
8) Make sure that your machine's fan is unobstructed and operating
9) Use a single AC power outlet with enough grounded power sockets for all
your equipment. This keeps the AC polarization correct between all your
equipment power supplies. If you examine a three prong outlet, you will
notice that it looks like a pair of eyes with a mouth. The mouth is
supposed to be electrical "ground"; the smaller slot is the "hot"; the
larger slot is "neutral". A power plug without a ground prong may have
one of its contact blades larger to fit only in the "neutral" slot. Don't
ever defeat it's purpose. To do so will endanger you and your equipment.
10) This should have been ICHI BAN: Never connect or disconnect cables
while equipment are powered, or blindly probe for a mating. This includes
your printer, external drives, modems, and other peripherals. Modems, for
instance, have +/- 12 volts on its pins. Damage can result when these
pins accidently touch the wrong pins on the computer. Always check to see
that you have the appropriate cable and cable adaptions before you attempt
usage.
11) Don't guess where the cables connect. Look where you plug your
equipment. The A2000 has a round DIN connector for the keyboard. Always
make sure the connector marker is on top before plugging. Don't do as
many people do. Don't insert and then twist until it fits. This will
slowly damage your connectors. IBM PC keyboards are not compatible.
12) Be very careful that the metal band around your mouse connector
doesn't short the pins of the mouse port when inserting.
13) If you encounter a power failure, turn-off all your equipment. When
power is turned on by your Electric Company, your equipment may experience
damaging power spikes or fluctuations.
14) Remove disks when shutting-down a system. Park your harddrive if it
is not the auto-parking type.
15) Video monitors develop high levels of static electricity. It is best
to plug the monitor and computer into the power outlets before connecting
the monitor cable. Always use a 3-prong power outlet. If your monitor plug
wasn't designed with a ground prong, use a power outlet that is correctly
polarized.
16) Always snug and not tighten the thumbscrews or clips to your
connectors.
17) Never place magnets near your monitor. This includes speakers,
printers, and telephones which develop magnetic energy.
18) Be sure to include in your startup-sequence file a stack command.
However, programmers should check the stack size if they need more than
4000 bytes-Operating System overhead. I *don't* increase my stack, or if I
do it's to 8000. (Now you know what me, myself, and I do.)
19) Before working on the interior of your computer, always touch either
the disk drive's or power supply's metal casing to discharge any damaging
static electricity.
20) The Amiga monitors have a metal shield installed under the casing. If
you are using a non-Amiga monitor, make sure that your monitor has some
shielding or make one using a metal kitchen tray (?).
21) Don't mix and blend versions of operating systems. You are asking for
problems and will get them most of the time. If you are still using older
software, you are asking for problems anyway.
22) When paying for shareware and you want a response from them, cut the
bill in half and staple a note as to where the other half went. Nah, don't
do it; it's illegal. Darn my buckies! I just became a felon when I
thought
of an excellent programmer.
23) When plugging in cards for the A2000 Amiga, there is the end of the
card which screws to the back of the Amiga. The metal bracket, which is
attached to the card for this purpose, has a tendency to catch at the
bottom of the bracket to the casing of the Amiga. To seat properly, the
bracket must be pushed against the back of the Amiga and then it will move
further down. Make sense? The main point is: Don't force the bracket to
seat and especially don't use the screw to force it to seat! Always screw
the cards down to prevent shorts
24) Genlock for the Amiga may need some modifications to sync properly.
The modification needs to be done on the early models and requires that
R55 resistor be removed and R108 to be changed to 1.5K ohms. R55 is a
4.7K ohm resistor located near the Q3 transistor, and R108 is a 1K ohm
resistor located near pin#10 of the MC1377 chip.
25) The composite video of the Amiga A1000 needs color correction. Your
red, greens, and blues may not look correct. The modification is simple;
just remove resistor R140; located on the rear-left of the motherboard. On
some A1000's, R140 will have to be replaced with a 470K ohm resistor
instead.
26) CORRECTED!
27) Keep your equipment out of sunlight; even when reflected by mirror or
walls while you are away from home. Overheating problems are increased if
the power supply vents are blocked or if it is resting on a rug. Keep the
power supply in a well ventilated area.
28) You cannot keep your cat or dog's fur out of your internal disk drive.
The fan sucks through there. Internal drives now have spring loaded doors
on the front which help in reducing contamination.
29) A clean mouse is a healthy mouse. Clean your ball and rollers with Q-
Tips, rags, toothpicks, picks, and jack-hammers.
30) Sticky keyboard keys? Remove that key button with a chip puller and
clean both button and switch with Q-Tips and alcohol. If your lucky, the
shank of the key switch isn't split. If it is, The split will widen in
the switch and wedge. Replace the switch or oil the shank with 3in1 oil
only. You may get lucky and find a repair station with some damaged
keyboards with good switches.
31) Does your monitor seem to sink into your A1000 computer case? Put a
plywood or 1/4 inch plexi-glass platform underneath. Does your A2000
keyboard seem to sink in the middle? Re-enforce the middle of the
keyboard's circuit board with a rubber spacer. Does this list seem a bit
long? Make some hot apple cider and come back here.
32) If one or more of your mouse buttons goes flaky, it can be replaced.
If the switch is "Flag", with a square body about 12mm in size with four
leads you may be in luck. If the switch is the type where the actuator is
completely flush to the switch body, the replacement part can be had from
Panasonic; Digi-Key (1-800-DIGI-KEY) sells it as part #P9950, 36 cents
each. If the switch button is slightly raised from the main body (by about
1mm) you will either need to adapt the above part or try and find a better
match. Mouser electronics (817-483-4422 or 619-49-2222) part # 10KB001,
49 cents each, *might* do the job. Some mice switches are dual switches
with only half being used! Use the other half by rotating the switch 180
degrees.
33) GET MEMWATCH from John Toebes!!
34) CORRECTED!
35) Dead Issue.
36) Ribbon cables should never be bent at angles to the degree of being
sharply folded. All folds of ribbon cable should gently loop. A sharp
crease can damage, short or break the wires inside the ribbon cable. In
the cable from the disk drive mechanism, this can mean Guru's or the
device not being recognized. MANY RIBBON CABLES FOR THE BRIDGECARD HAVE
BEEN DAMAGED BECAUSE OF THE CREASES IN THE PACKAGING OF THE PRODUCT. THIS
HAS DAMAGED DRIVES AND BRIDGECARDS. IF A RIBBON CABLE IS SHARPLY FOLDED,
USE AT YOUR OWN RISK.
37) Copy and run questionable or unknown programs in RAM disk with your
disks removed or write protected. This will prevent you from crashing the
disk drives and damaging the disks.
38) Corrected!
39) For A2000 users with BridgeCards, keep the ribbon cable going to the
5 1/4 floppy away from the motherboard. Lay the ribbon cable on top of the
cards instead of underneath. The ribbon cable picks up interference which
can cause your machine to intermittently GURU or cause devices not to be
recognized. (*** note *** Some A2286 bridgeboards will display parity
errors. Return these for exchange.)
40) All computer equipment need a minimum amount of time before powering
back on-line. For the Amiga A1000 and A500, you must wait a minimum of 20
seconds before power-up and as long as 30 seconds or more for the A2000
Amiga. Computers need time to completely power-down and discharge all
voltages which may be sustaining corrupted data in RAM and other chips.
41) If your computer monitor remains powered and unattended for extended
periods of time, use a display blanking program. This type of program
will "black-out" your display until there is some kind of user action from
the mouse or keyboard. Your display will temporarily "black-out" after a
set number of minutes of inactivity. Public domain programs like "PopCLI"
from the Software Distillery and "ScreenSaver" from Perry Kivolowitz are
good examples. Leaving the colors stationary for days on end will
burn-out the phosphors of the monitor leaving you with a ghost image
of the display forever. I set my screen to black-out after 10 minutes of
inactivity.
42) It's a good idea to assign your T: directory to RAM:T before executing
any command script. The reason is increased speed and less drive activity.
(Hans Hansen)
Newsgroups: comp.sys.amiga
Subject: Screen colors and other boot things
Date: 16 Jul 87 01:42:24 GMT
Dark gray Ok Hardware
Light gray Ok Software
Red Bad ROM Checksum
Green Bad RAM
Blue Bad Custom Chips
Yellow Exception
(INITIALIZATION FROM OS ROMS)
Clear Chips
Disable DMA and Interrupts
Clear the Screen
Check the Hardware
Pass or fail the Hardware to the Screen (BLUE|BAD) (DarkGray|OK)
Checksum the ROMs
Pass or fail the ROMs to the Screen (RED|BAD) (LightGray|OK)
System setup (..is finished)
Check the RAM at $C00000
Move SYS_BASE to $C00000 if it exists
RAM Test ; hummm.... not very good though needs to indicate hex location
Pass or fail the RAM to the Screen (LED Blinks 9short 1long | GREEN | BAD)
Check the Software
Pass or fail the Software to the Screen (Yellow|BAD) (LightGray|OK)
Set up the RAM
Link the Libraries
Find External RAM and link it to the list
Set up Interrupts and DMA (for boot drive especially)
Start default Task
Check for 68010, 68020, and 68881
Check for an Exception (System Alert?)
System Reset (..Let the good times roll!)
Hope this helps....
--
------------------- // ----------------------------------------------------
Erick Parsons // Knowledge is little more than knowing the questions
------------- // erk@americ.UUCP or ..ames!pacbell!sactoh0!americ!erk
Sacramento Ca \\ // GEnie: E.PARSONS %-) Hamatuer Radio N6RZB
-------------- \X/ --------------------------------------------------------daveh@cbmvax.UUCP (Dave Haynie) (09/22/89)
in article <1982.AA1982@americ>, erk@americ.UUCP (Erick Parsons) says: > This can be especially prominent with fast expansion devices like hard > drives and frame grabbers. Number one on the list of bad boards are all > those RAM boards with 150 nano-second RAMs. This is the time it takes the > RAM to access valid data. The smaller this number the better. You're confused. While it's true that the rating of the DRAM device, such as 150ns, indicates one aspect of the device's access time, that's hardly an indication of performance. It's certainly possibly to build a perfectly acceptible, full speed Amiga memory board with 150ns parts. A 150ns device has a cycle time of 270ns or better. The _minimum_ memory cycle time on the Amiga bus is 560ns. Clearly, some margin exists for a good design using 150ns parts. In fact, the CHIP memory in your system is very likely 150ns DRAM, and it's actually running 280ns cycles (interleaved Agnus and 68000 accesses). Now it's also a fact that, with a bad memory board design, even 80ns parts aren't going to help you out much. If you put 80ns chips into any A2000 style memory board you're wasting money. In general, if you use any part that's rated faster than a board calls for, you're wasting money -- the part's speed is only a potential speed. The actual speed of operation is limited by [a] the Amiga system, which sets the minimum cycle time of 560ns, and [b] the memory board design, which could impose wait states, depending on it's design. Most of the memory boards out there, like A2052 or A2058, ASDG, MicroBotics' 8-Up, etc. run at the full bus speed with generally hidden refesh cycles. Even if a memory board does add wait states, all that's going to do is slow you down, it's not going to make anything unreliable. And in most cases, changing to faster DRAM isn't going to help; the memory timing is set by the board design. The only case in which changing to a faster memory device will help is if you have a memory board that, for some reason, is populated with parts that are too slow for it's design. Certainly the reputable manufacturers don't ship memory boards with incorrect parts, and they also don't recommend the wrong parts for boards that are shipped unpopulated. So unless you're experiencing flakey operation with a memory board from some fly-by-night operation, or on something you hacked together in your cellar, you're not likely to gain anything, except space in your wallet, by going to a faster set of DRAMs. > Erick Parsons // Knowledge is little more than knowing the questions -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough
jwright@atanasoff.cs.iastate.edu (Jim Wright) (09/22/89)
In article <1982.AA1982@americ> erk@americ.UUCP (Erick Parsons) writes: | For those of you that don't have access to a descent BBS here is something | that I found on one of our local boards that looks VERY useful. [...] | Amiga Disk Drives | 1) Clean with Q-tips and alcohol | a) if heads are sticky when they touch each other, clean heads | with "KESTER Rosin Residue Remover". Just a little warning: Q-tips have a small amount of wax added to them so that they retain their "50% more head". Use medical or electronic grade cotton swabs instead. Also, be careful about what alcohol you use. Some leave a residue, depending on what else has been added. -- Jim Wright jwright@atanasoff.cs.iastate.edu
dougp@voodoo.ucsb.edu (09/22/89)
-Message-Text-Follows- In article <7966@cbmvax.UUCP>, daveh@cbmvax.UUCP (Dave Haynie) writes... >has a cycle time of 270ns or better. The _minimum_ memory cycle time on >the Amiga bus is 560ns. Clearly, some margin exists for a good design using ^^^^^ Is this always true? My understanding is that the 68000 only needs to access ram every other cycle which would explain the timing (well almost, 1/7.14Mhz = 140ns, *2=280ns). But other devices hanging on the bus, say a hard disk with DMA, or even the 2620 might be able to access the bus every cycle. Perhaps you could help with a simplified discription of what determines the bus timing especialy where that factor of 2 and 4 comes from >Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" > {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Douglas Peale
rar@auc.UUCP (Rodney Ricks) (09/22/89)
In article <2367@hub.UUCP> dougp@voodoo.ucsb.edu writes: >-Message-Text-Follows- >In article <7966@cbmvax.UUCP>, daveh@cbmvax.UUCP (Dave Haynie) writes... >>has a cycle time of 270ns or better. The _minimum_ memory cycle time on >>the Amiga bus is 560ns. Clearly, some margin exists for a good design using > ^^^^^ Is this always true? My understanding is that >the 68000 only needs to access ram every other cycle which would >explain the timing (well almost, 1/7.14Mhz = 140ns, *2=280ns). I'm no hardware expert, but from my understanding, doesn't the 68000 have four CPU clock cycles for every memory bus cycle? If so, that would change your timing calculation to be... 1 / 7.14 Mhz = 140ns, 140ns * 4 = 560ns >But other devices hanging on the bus, say a hard disk with DMA, or >even the 2620 might be able to access the bus every cycle. Maybe the bus was designed to run only as fast as the 7.14 Mhz 68000 can access it. >>Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" >> {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy > >Douglas Peale -- "We may have come over here in different ships, but we're all in the same boat now." -- Jesse Jackson Rodney Ricks, Morehouse Software Group
peter@cbmvax.UUCP (Peter Cherna) (09/22/89)
In article <1545@atanasoff.cs.iastate.edu> jwright@atanasoff.cs.iastate.edu.UUCP (Jim Wright) writes: >In article <1982.AA1982@americ> erk@americ.UUCP (Erick Parsons) writes: >| Amiga Disk Drives >| 1) Clean with Q-tips and alcohol >| a) if heads are sticky when they touch each other, clean heads >| with "KESTER Rosin Residue Remover". > >Just a little warning: Q-tips have a small amount of wax added to them >so that they retain their "50% more head". Use medical or electronic >grade cotton swabs instead. Also, be careful about what alcohol you >use. Some leave a residue, depending on what else has been added. > >-- >Jim Wright >jwright@atanasoff.cs.iastate.edu Here's something I picked up in my old days working with fiber optics: DO NOT use swabs that have plastic sticks. You'll get a faint milky residue because the alcohol dissolves the cheap plastic. Proper cotton swabs designed for other than ears have wooden sticks. Peter Cherna "The above opinion is mine, and does not necessarily represent that of my employer."
maniac@arrakis.nevada.edu (ERIC SCHWERTFEGER) (09/23/89)
Having done designs for a 68000 based single board computer with DRAM memory (years ago), I can add to this discussion on what speed memory is needed on the amiga, While it is true that the memory cycle on the amiga (for the cpu) is 560 ns, the CPU doesn't give the memory that much time to read. First of all, the address isn't made available until half way through the first clock cycle, and doesn't say that that is a valid address until the end of the first clock cycle (you can, however work around this). Now, the data is expected in by the start of the fourth clock cycle. This gives the memory 2 clock cycles, or 280 ns to respond. Now, you can figure on another 100 ns of overhead for memory decoding, buffering, etc. Remember that light only travels less than a foot in 1 ns, and those paths through the chips are hardly straight, or at full speed. The overhead gets even worse when you have to deal with an expandable system like the Amiga. Now that all that is done, you have about 180 ns for a memory access, unless the memory board is poorly designed or some other design consideration took precidence. In the Ram board I have (EXP -1000), I have a mix of 150 ns and 120 ns memory, and unless I pull all my 150 ns chips, I need to let my Amiga warm up for a few minutes in order to boot. I have heard of one memory expansion/hard disk unit (can't remember the name), that requires 80 ns rams, due to higher overhead. Hope this information helps. Eric Schwertfeger, UNLV, maniac@arakis.nevada.edu
daveh@cbmvax.UUCP (Dave Haynie) (09/25/89)
in article <840@unsvax.NEVADA.EDU>, maniac@arrakis.nevada.edu (ERIC SCHWERTFEGER) says: > Keywords: memory bus > While it is true that the memory cycle on the amiga (for the cpu) > is 560 ns, the CPU doesn't give the memory that much time to read. True -- it looks like this: +------------Cycle Time = 560ns---------+ | | s0 s1 s2 s3 s4 s5 s6 s7 +----+ +----+ +----+ +----+ +--- | | | | | | | | | 7M -+ +----+ +----+ +----+ +----+ | | +-------280ns-------+ Access Time > Now, the data is expected in by the start of the fourth clock cycle. This > gives the memory 2 clock cycles, or 280 ns to respond. But, we are talking only _access_ time for memory, too, not just the 68000. Both have cycle times, both have access times. > Now, you can figure on another 100 ns of overhead for memory decoding, > buffering, etc. If you have 4 levels of buffering between the 68000 and the board (as with autoconfigured boards), you might get at worst 50ns of delay. It's not even as bad as all that. If you're building a DRAM board, you _could_ assert RAS* as soon as AS* falls, even before you're certain of SLAVE* being valid. Give the DRAMs 180ns from RAS* (room for buffer delays and slop), and you're left with over 70ns from the time AS* is valid on your board before RAS* need be asserted. That, my friend, is FOREVER. > In the Ram board I have (EXP -1000), I have a mix of 150 ns and 120 ns > memory, and unless I pull all my 150 ns chips, I need to let my Amiga > warm up for a few minutes in order to boot. Like I've said before, it's up to the designer to insure his/her design will work with any specific speed part. You can certainly simplify your design in many cases by requiring a faster part. I'm sure you don't have to pull the 150ns DRAM from your Amiga's motherboard to power up :-). > > Eric Schwertfeger, UNLV, maniac@arakis.nevada.edu -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough