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APPLE II DEVELOPMENT FORUM CONFERENCE LOG
Tuesday, May 1, 1990 10:00 p.m. eastern time
Topic: Operating Systems
Forum Leader: AFL Dyfet
AFL Dyfet Good evening and welcome to the Apple II Development Forum.
Tonight our topic
AFL Dyfet is Operating Systems. We will be using PROTOCOL. This means that
if you have
AFL Dyfet a question to ask, enter a '?' on a line by itself, and if you
wish to comment
AFL Dyfet on the question being asked, enter a '!' on a line by itself. You
will each be
AFL Dyfet called in turn. I believe Keith had the first question....GA
Kieth...
KeithR4 No questions yet, GA
Coach101 I think Keith asked a question before the conference started about
what was meant by
Coach101 channels? If you are a certified developer you ave access to
AppleLink (Apple Edition) and can ask
Coach101 very detailed programming questions in an official manner (i.e.,
channels).
AFL Dyfet GA Keith...
KeithR4 Thanks for answering
KeithR4 ga
AFL Dyfet Okay, I believe Parik now has the floor...
AFA Parik has anyone here written a macro program? if so, whats the best
way to
AFA Parik intercept key-calls? ga
AFL Dyfet GA Keith...
KeithR4 What language and development system are you using Parik?
AFA Parik asm65816
KeithR4 Apw or Merlin?
AFA Parik orca :)
Coach101 PRIZM or EDIT
KeithR4 Sorry can't help you there. ga
AFA Parik rose (heh) ga, never mind
AFL Dyfet :) Okay, getting back to your question, I believe there is some
sample source
AFL Dyfet on how to steal keyboard interrupts from C...you may wish to start
by looking
AFL Dyfet at that.
AFA Parik ok! thanks
AFL Dyfet Okay, Coach now has the floor...GA Coach...
Coach101 My question has to deal with intermodule communication...
Coach101 Specifically, if you have a driver, a permanent init, and a Cdev
that comprise some variety
Coach101 of service support for an application program, how can the init,
driver, and Cdev communicate with
Coach101 each other. ga
AFL Dyfet My first thought is message center...GA Dave...
Dave Lyons Use MessageByName and MessageCenter to publish an
Dave Lyons address that the others can look up & then call. (Several of
your
Dave Lyons compenents can publish their own hooks, or invent your
Dave Lyons own variations. I'm using this approach in a
Dave Lyons not-quite-released-yet Nifty List, and it works well. Now, Matt
has another approach: (GA)
AFA JoeyS <drooling over the thought of a new NiftyList...>
Matt DTS Dave (and Dave)'s method is well and good, but if you really have
a GS/OS driver installed, it's not
Matt DTS necessary.
Matt DTS If you have a GS/OS driver (which, by the way, is absolutely the
most intelligent way to control
Matt DTS hardware), you make it so that the driver handles ALL the hardware
requests through DControl, DStatus,
Matt DTS DRead and DWrite calls. If you need to set default parameters
(for example, default color on a color
Matt DTS printer), use DControl. If you need to know if the printer's
online, use DStatus.
Matt DTS Drivers are present before CDevs and Inits are loaded. If the
driver doesn't find it's hardware, it
Matt DTS will be unloaded by the Device Manager.
Matt DTS So:
Matt DTS Get a unique Device ID from DTS for your driver, so you can find
it with a DInfo scan just like you ca
Matt DTS (can) currently find servers or SCSI hard disks. Have your
CDev/Init search for the driver and call
Matt DTS it to do all the work.
Matt DTS (If you want to use MessageByName to indicate that the driver's
there and what it's device number is,
Matt DTS that's dangerous - new drivers can be installed at any time so you
should search every time.)
Matt DTS It's simple and lets the driver do all the work, which is what you
really want anyway. GA.
Coach101 Matts approach is much closer to my requirement...
AFL Dyfet GA Dave...
Dave Lyons So, how does the CDev communicate with the permanent init part?
Dave Lyons (Or doesn't it need to anymore?)
Coach101 But, can I have drivers that have no hardware associated with
them? e.g., they do funny things
Coach101 with an existing driver (AppleTalk for example)?
Matt DTS No. Drivers deal with hardware, not other things (especially not
other drivers).
Matt DTS You can, however, write your own AppleTalk protocols and get them
loaded (if you like).
Coach101 But, I could have a device driver that talked to the AppleTalk
manager right?
Coach101 Wrong... Bad, dumb, studid idea!
Matt DTS You can have a device driver that makes AppleTalk calls ($E11004,
or whatever). You can't have a
Matt DTS device driver that makes calls to the AppleTalk drivers.
Andy Stein Burger Bill is writing a Hewlet-Packard driver at 300 DPI!
Matt DTS You can write a driver that communicates with the supervisory
drivers, but there isn't an AppleTalk
Matt DTS supervisory driver. (Protocol?)
Coach101 Thanks for the ideas, I will mull them all over and see what pans
out.. ga
AFL Dyfet Okay, I see that Marty is next...GA Marty...
AFL Marty One of the members of AOL is having some difficulty with his hard
drive....
AFL Marty and I said that I'd ask this question here tonight...
AFL Marty The member is using a SCSI hard drive with the DMS SCSI card
....
AFL Marty (DMA SCSI)...
A2GS DMA
AFL Marty (thank you)
Matt DTS (the GMTA SCSI card)
A2GS ABCD
AFL Marty and he is getting what sounds like the same unclaimed interrupts
errors...
AFL Marty that I've heard about before. He is using an internal modem...
AFL Dyfet Is he using the new SCSI drivers?
AFL Marty Is there some way to work around this problem?
AFL Marty Yes, he uses the new drivers.
AFL Dyfet GA Matt...
AFL Marty GA
Matt DTS 1) Using the new drivers is not enough. He must use the INSTALLER
that came with the card to install
Matt DTS the modified GS/OS required by the new drivers/manager.
Matt DTS 2) When using the new OS, >64K interrupts is not a fatal error.
It will still ask you to "restart"...
Matt DTS ...but if you press return, you'll be returned to the application
with no ill effects.
Matt DTS 3) (off-chance) When using the new drivers/managers with the OLD
SCSI Card (Rev. C), it's vital that
Matt DTS you have proper termination - one terminator on the first and last
device on the chain (or just one if
Matt DTS you have just one device). The old manager would let you get away
with bad termination; the new one
Matt DTS does not. Take it from someone who watched SCSI have a party on
his data.
Matt DTS GA.
AFL Marty Thanks for the info. GA
AFL Dyfet Okay, I see that Keith has the next question...GA Keith, you have
the floor
AFL Dyfet now.
KeithR4 Is there any Pascal sample source code for doing list controls?
AFL Dyfet GA Matt...
KeithR4 I'm using TML Pascal II and I can't seem to get a list control to
work at all.
KeithR4 ga
Matt DTS Do you mean lists or the new 5.0 Extended List Controls?
KeithR4 either
Matt DTS List Controls are easier than lists. We haven't released any
samples, but we will be within the next
KeithR4 I tried the normal lists first. Didn't try the extened. I nedd
to create it
KeithR4 on the fly ga
Matt DTS month or so. Some will also be in the final Toolbox Reference
Volume 3 from Addison-Wesley.
Matt DTS (GA)
AFL Dyfet GA Dave...
Dave Lyons Keith, do you want the list in a regular window, or inside a Modal
Dialog?
Dave Lyons And, question 2, what went wrong when you tried it?
KeithR4 In a regular window ga
KeithR4 When I selected an item all of the items became garbage
Dave Lyons Okay, so it showed up correctly to start with, but
Dave Lyons when it tried to redraw later, the item text was all screwed up,
right?
KeithR4 That's correct
Dave Lyons The strings for the items have to *stay* in memory where they were
when you fed them to the
Dave Lyons list manager...sounds like you made a *local* array of strings,
maybe, so they went away?
KeithR4 Do I need to do some handle locking?
Dave Lyons Are your strings in a handle?
KeithR4 Yes, they may have been local variales.
Dave Lyons (I mean, one you specifically allocated?) Or what?
KeithR4 No, they are not in a handle, should I allocate one?
Dave Lyons Locals sounds like a very good bet--make 'em global or otherwise
long-lived, and life will be good.
KeithR4 Thanks, done.
Dave Lyons (No, there's no special advantage to having 'em in a handle...you
still have to have them somewhere
Dave Lyons to put them in the handle anwyay....) ga
AFL Dyfet Okay, Parik has the next question...GA Parik...
AFA Parik will gs/os load cdas into special memory if bit 12 is not set in
the omf field
AFA Parik and will gs/os purge at least level 3 before running prodos 8?
ga
AFL Dyfet GA Matt
Matt DTS ExpressLoad (and perhaps the System Loader, not sure) always
attempts to load non-special memory
Matt DTS before using special memory. If no special memory is not set, it
will be allowed but not preferred.
Matt DTS 2) No. GS/OS asks for the P8 memory and if some stuff needs to be
purged to get it, it will be purged
Matt DTS to get it. It doesn't go around kicking out people's dormant data
for thrills.
Matt DTS (GA)
AFL Dyfet GA Dave...
Dave Lyons Checking, but I don't think CDAs (when loaded by the system) get
to use special memory even if
Dave Lyons no regular memory is available. That's the flag on InitialLoad,
right?
AFA Parik i allocate a direct page in my Cda and it must be left after cda
is exited. i
AFA Parik use $4115 as memory-bits, and it doesn't get purged before running
p8. :(
WinkieJim Would prevent using P8 programs if they were loaded into special
memory
Matt DTS The memory manager will purge your handle if it's in special
memory to get it for P8 - if it can.
AFA Parik ga, i just have a key for disposing DP memory inside program.
kinda messy.
Dave Lyons Ah, but it would
Matt DTS It can't purge locked blocks, for example.
Dave Lyons purge levels 3 and 2 first, before getting rid of his level-1
blocks in bank 0. Are you leaving
Dave Lyons that page there while not in your CDA on purpose, or are we just
trying to explain the results
Dave Lyons of a bug?
AFA Parik no, the page is used by a background interrupt.
Dave Lyons Hmmm....
AFA Parik (after exiting CDA). it uses Memory Attributees of block may be
moved or
AFA Parik purged, and purge level 01.
WinkieJim That's a no-no...I think
AFA Parik I've used the WHERE utility of Prosel-16, and the PURGE.MEM.
It'll get rid of
AFA Parik it. But gs/os won't! :(
Dave Lyons You need a way to shut that down nicely before P8 launches.
AFA Parik ga anyways, message-base discussion is better.
AFL Dyfet GA Winkie...
WinkieJim Is there any way you can have your interrupt routine allocate the
direct page
WinkieJim itself when it's called so you don;t keep the direct page all the
time?
AFA Parik good idea!
WinkieJim Just a suggestion gs
WinkieJim ga
Coach101 You cannot use the MemoryManager at interrupt time... Right?
AFA Parik wait, that won't work. the sound tool uses a direct page also and
is left on
AFA Parik :( ga
Matt DTS (Wrong.)
WinkieJim Sorry just a thought...
AFL Dyfet GA with your comment, A2...
WinkieJim (i usally just save a few bytes on the direct page and put them
back when i'm
WinkieJim done...I know: very dangerous.
A2GS Without offending Matt, :) can you have the sound tools generate
interrupts
A2GS which are vectored to your sound interrupt handling routine which
allocates
A2GS or rather sets the DP to your address?
A2GS Of course the problem then is resetting the DP.
AFA Parik yes, but the sound tools need a direct page!
AFA Parik i think i'll leave the sound tools off and try replacing $E1/002C.
ga with the
AFA Parik next q
A2GS Oh, I see...never mind I thought you meant that the sound tools
needs the DP
AFL Dyfet Okay, I believe Andy has the next question...GA Andy...
Andy Stein When I use System 5.0.2 with my Vulcan 40 Megabyte hard drive,
every once in a
A2GS during an interrupt. (A2GS<---SMACK)
Andy Stein while, I find all my files strewn about the directory, in no
particular order.
Andy Stein It seems to occur after I've booted a System disk that does not
have the Vulan
Andy Stein driver on it. Also, why won't some Prodos 8 and 16 programs run
properly on it
Andy Stein ?
Andy Stein ga
AFL Dyfet GA A2....
A2GS You probably have the FINDER info files on the same sys. Disk
which contains
A2GS your Vulcan Drivers and when you boot up another disk, the Finder
can't "FIND"
A2GS the files. I Think? :) GA
AFL Dyfet GA Matt...
Matt DTS Not probable. The Finder only stores info files for a volume on
that volume, not other volumes.
Andy Stein Even after, when I boot up with Vulcan, the files are still messed
up.
Matt DTS It doesn't, for example, put any information about your hard drive
on a floppy, or vice versa.
Matt DTS "strewn about in no particular order"
Matt DTS Lemme point out that files on ProDOS disks *aren't* in any
particular order. The Finder will always
Matt DTS sort them by some criteria, but other directory listers (ProSEL,
APW/ORCA, BASIC.SYSTEM) don't, so
Matt DTS they'll seem to be in some weird order. Is this what you're
seeing?
Matt DTS (ga)
AFL Dyfet GA Head...
Andy Stein I mean, the files aren't in the visual order that they were
originally in.
HeadCase Could it be you have the preferences set on one finders not to
save finder info?
Andy Stein For example, the AppleWorksGS is moved from the top to the bottom
left, the
Andy Stein Xenocide from the bottom to the middle.
Andy Stein (On the main directory.)
A2GS That's what the Finder files are used for (among other things)
AFL Dyfet Coach...
Coach101 Finder defaults come from the disk that you boot from....
Coach101 The placement of files on the desktop (if you drag
Coach101 files to the desktop) come from the device containing the
files....
Andy Stein Usually PD disks mess it up, like Bouncing Bluster, and that
Tertrisosas game.
Coach101 This can get very confusing if you boot from multiple disks into
the Finder...
Coach101 Could some combination of this be the difficulty?
Andy Stein Yes, Coach, that's exactly what I mean.
A2GS I know that...but it is possible (although far fetched,
admittedly) he may have
A2GS accidently copied the finder files to his sys. disk.
Andy Stein Some disks only run from their own version of the Finder, and not
my hard
Andy Stein disk's.
A2GS Only thing I can think of...that's why I'm so stubborn :)
sidley bye folks wierd stuff here...
AFL Dyfet Perhaps we can move this discussion into the message base...
Andy Stein I'm afraid to use Bouncing Bluster and Tertosisas, because evry
time, my
Andy Stein main directory gets messed up.
A2GS LOL Andy
AFL Dyfet Okay, I believe Scott has the next question...
AFL Scott Has anyone seen problems with self-modifying code on a GS with a
Transwarp?
A2GS But only while your using that app. under that SYS. disk, right?
Coach101 No, but since they hav a cache, it certianly could be a problem!
AFL Scott Reason I'm asking is that I'm working on a contract where the code
is
AFL Dyfet Scott, the Cache may be killing you (as Coach just said)...
AFL Scott heavily self-modifying and it appears to work on some TWGS's but
not on
AFL Scott others.
AFA Parik turn off interrupts before modifying?
AFL Dyfet GA Dave...
AFL Scott I'm aware of that, but one would think that the cache would see a
miss and
AFL Scott re-read.
Dave Lyons Before we jump off the deep end, isn't their cache write-through?
It's pre-fetching that would kill
Dave Lyons self-modifying code, and there's enough self-modifying code in the
Apple II world that
Dave Lyons I don't see how it can be a problem (I mean, everything would
break). Including all OS calls
AFL Dyfet Most self modifying code I have seen does have some distance
between the
AFL Dyfet instructions doing the modifying, and the modified
instruction...
AFL Dyfet Usually it's a jump address being co-erced further in, or some
games with an
AFL Dyfet absolute address being used as a pointer in a LDA/STA...
Coach101 Scott, you probably need to call AE and get some details on their
cache implementation.
Coach101 And let us know what they say!
AFL Dyfet Scott, also, are you modifying the NEXT instruction to be
executed, or
AFL Dyfet something further in the program that comes in later?
Coach101 I presume all the cards pass AE built-in diagnostics?
AFA Parik (someone should also tell Zip Chip @ AppleFest just in case)
AFL Dyfet Another tricky one may be branches...some cache systems try to
follow both
AFL Dyfet paths, just in case...
Coach101 And then there is DMA!
AFL Dyfet We lost Scott...
AFL Dyfet Well, without knowing the specific cercumstances, there isn't much
to speculate
AFL Dyfet on...A2 has the next question and the floor now...GA A2...
A2GS Where can I get info on writing decompression routines for the 3
(I believe)
A2GS standard $C0 filetypes.
A2GS ?
A2GS GA
AFL Dyfet GA Parik...
AFA Parik source code is provided in the adv library. i wrote a exe file
that will unpac
AFA Parik all three. look for dev util #1 source code. there are also
others. ga
A2GS Prefer text.
AFA Parik (a filetype technote details the exact format if you wish)
A2GS APW Shell file?
AFA Parik apw/orca/merlin/prosel
A2GS Thanx GA
AFL Dyfet Okay, I believe that Dave Lyons has the next question...GA
Dave...
Dave Lyons Oh, hi...wasn't paying
Dave Lyons attention. :) Anyway, as I was saying
Dave Lyons before I got so rudely kicked off my connection ("Login failure:
your account is already
Dave Lyons logged on."), uh,
A2GS Dave, just plug it into the wall and turn on the button on the
back. :)
Dave Lyons there is self-modifying code
Dave Lyons in the APW C library routines that make GS/OS calls, so if the
TWGS didn't deal with
Dave Lyons self-modifying code, I think we'd have noticed it already. ga
Coach101 It may have to do with the spacing between the
Coach101 modification and the modifier and how recently
Coach101 the modified element was cached....
AFL Dyfet Considering how many 'esoteric' coding practices have been used in
the history
AFL Dyfet of Apple II programming, I suspect you are correct, Dave :)...but
it would have
AFL Dyfet been helpful to know the exact circumstances he was working
with...
Dave Lyons FYI, the self-
Dave Lyons mod code in the library is STA blah, JSL $E100A8, blah(word).
It's very near-by in
Dave Lyons memory, but then it isn't actually fetched for a while. Hmmm.
AFL Dyfet Dave, that's near, but not as near as INC blah, LDA #blah, for
example :)
Dave Lyons (What? INC Blah+1, Blah: LDA #blarg ?)
AFL Dyfet Yes...
Dave Lyons Well, I have no TWGS here at home...somebody try it.
A2GS Why not just INC Blah ?
AFA Parik will try, brb
Dave Lyons (Because INC Blah would make the LDA # into a TAX. :)
A2GS Blah could be holding a number.
AFL Dyfet That would also be self modifying, A2 :)...
AFL Dyfet But it would be the LDA that is modified :)
A2GS Just the fact that the number at blah is incremented...means that
blah is being
A2GS modified.
A2GS blah doesn't have to be an op-code.
Dave Lyons Oh, I see what you're saying...I guess the idea
Dave Lyons is that if there's a problem with self-mod code, it's because of
the processor (or its close
Dave Lyons friends) fetching *instructions* ahead, but always doing a real
memory or cache access for data,
Dave Lyons since it *expects* that data changes. Yes?
AFL Dyfet Yes, basically, Dave...I've seen MUCH WORSE problems on heavily
cached RISC
AFL Dyfet machines, for example :)
A2GS couldn't be, otherwise there would be a potential problem with any
INC op.
AFL Dyfet Well, now that Scott is back, we may find out just what he was
modifying :)
AFL Scott Dave, I was wondering if you could explain your use of
Pre-Fetched.
AFL Scott (I'm sorry, I was bumped and the system wouldn't let me sign back
on until
AFL Scott the darn in use flag was cleared).
AFA Parik (it blew my motherboard! :) just kidding, worked fine)
Dave Lyons (Me, right?)
AFL Scott Right, Dave Lyons.
Dave Lyons What I was saying is that a write-through cache, like I believe
the TWGS has,
Dave Lyons doesn't present a problem, because all stores go
Dave Lyons to real memory & maybe also to the cache, but they never leave
outdated information in the
Dave Lyons cache. Pre-fetching, or pipelining (if I'm using the term
correctly) would be some
Dave Lyons additional storage where upcoming instructions are stored, but
which *isn't* updated on writes. THAT
Dave Lyons would be a problem, but as far as I know the TWGS does NOT
implement anything like that. (I
Dave Lyons hypothesize that if it *did*, life would be very bad for a lot of
existing Apple II software. But
Dave Lyons I could be wrong.)
Dave Lyons ga
AFL Dyfet While performing the write to real memory (for the write-through),
the TW may
AFL Dyfet still acknowledge CPU requests from memory pre-fetched, HOWEVER,
it may not
AFL Dyfet immediately update the cache memory as well, since that would
waste an extra
AFL Dyfet (7mhz) cycle...this is typical in many RISC caching systems...
Dave Lyons Can you suggest a test that would resolve the question?
Matt DTS I think I'm gonna take off. G'night, all.
AFL Scott Thanks, Dave and David. A test.. yeah.
AFL Dyfet Try the inc BLAH, blah: lda #0, and see if a TAX was executed
before a brk :)
AFL Scott And I've done it... it works on my machine but has problems on
others.
AFL Dyfet (in other words, LDX #0, LDA #1, INC BLAH blah: LDA #0,
BRK...:)
AFL Scott See, I have a problem with self modifying code in terms of
reliability and
AFL Scott maintainability in APPLICATIONS.
A2GS Are we still on blah?
AFL Dyfet (wwops, make that LDA #0, LDX #1 :)
Dave Lyons Scott, on the machines where it
Dave Lyons malfunctions, does disabling the TWGS solve the problem?
AFL Scott Yes and no... The problems seem to stem from timing. So, when the
machine is
AFL Scott in Slow, it works. This isn't acceptable to me... Additional
problems surface
AFL Scott when Sane calls are caught by the FPE init ( I haven't seen those
either).
Dave Lyons Is any of your code getting executed at interrupt time?
AFL Scott For the record, it's not MY code.... Explain interrupt time.
Dave Lyons Well, interrupt time is when an interrupt has come along (a
heartbeat
Dave Lyons interrupt, sound interrupt, or whatever), but has not yet returned
control to the code it
Dave Lyons interrupted. Self-mod code is very scary if you've got any of the
same code running in the foreground
Dave Lyons *and* getting called from inside an interrupt...it's very hard to
be reentrant
Dave Lyons that way.
A2GS In other words, are any interrupt handling routines vectored
toward your code?
A2GS I believe that's what DAVE is asking, right?
AFL Scott No, there are no interrupt routines in the code I'm working with.
Only thing
AFL Scott that happens is a DMA comes along from a hardware device but that
is way after
AFL Scott this code is called.
Dave Lyons Yes, Thank you, Paul, you've crystalized my thoughts exactly.
Dave Lyons :)
A2GS Paul??
A2GS :)
Dave Lyons (That's what Letterman sez to Paul all the time)
A2GS Remind me to listen to Sheaffers return comment :)
AFL Scott IE... there is no interrupting going on... The DMA call is
initiated with
AFL Scott a JSL to the ROM on the Board.
AFL Scott And I don't see that, either.. but that's what they do...
Dave Lyons Well Scott, something *weird* is going on in them thar
machines...hard to tell what it is from
Dave Lyons here. You've *never* seen a problem w/o a TWGS in there,
though?
A2GS What do you expect...it's an Apple :)
AFL Scott Never. In fact the company I
AFL Scott am doing this for is recommending pulling the TWGS, and I find
that
AFL Scott an unacceptable compromised.
AFL Scott -d.
AFL Scott I shouldn't have asked this here, though. I should ask AE.
AFL Scott Rather I shouldn't have gone this deep.