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 1 
 on: May 20, 2022, 04:46:47 pm 
Started by rayarachelian - Last post by rayarachelian
Quote
* change the wave file size I'm using to several seconds instead of using looping - this would require more memory use and a work around, but it might work, haven't tested to see if I can stop the sound early successfully if it's something like 5-10 seconds of a wave file.

Nope, this doesn't work. I set the wav file to 10s, but when Sound.Stop() is called, it locks up on the mutex the same as LOOPING audio, so the real issue is with the Stop and not the LOOP.

 2 
 on: May 14, 2022, 05:21:38 pm 
Started by sigma7 - Last post by sigma7
Major rewrite

Note posting above: "Substantially rewritten due to erroneous thought that bus errors may occur before empty slots are encountered"

The technique described to hold a problematic bus cycle indefinitely for hardware inspection may simplify troubleshooting substantially!

It seems that the CPU board generates DTACK for all accesses that the MMU has been programmed to be RAM.

To determine the amount of RAM installed, the MMU is initially programmed to address 2MB of memory (4 MB in 3A 'square pixel' or correspondingly modified ROMs), then the ROM code tests areas of that RAM to see if it is indeed unique memory or just empty space. Once the size and physical address of RAM blocks is determined, the MMU is re-programmed to make the RAM contiguous starting at logical address $0.


 3 
 on: May 13, 2022, 06:20:52 pm 
Started by dmark - Last post by Lisa2
What model of monitor is that? Looks like a Conrac 38V44IOCA1?
Mine is a Conrac 38-V44IOA-A2.  Be careful before you buy one, there were many variations of this model and not all versions will support Lisa's scan rate.

Here are the specs:

Industrial Series #V44 - 15
technical data
High Resolution Monochrome Monitor V44 - 15
(15" = 381mm)
Category   Monochrome (CRT)
Format   Cabinet (Metal)
Model   V44 - 15"
Part Number   38-V44IOA-A2
Screen size   15" (381mm)
Max resolution   1000 TV lines center
800 TV lines corner
Phosphor   P4 (white)
Horizontal frequency   15-40kHz
Vertical frequency range   45-90Hz
User controls   Front: A/B Switch, Brightness, Contrast, H Position, H Size, Power, V Position, V Size, VTR Switch
Input voltage   100-240VAC 50-60Hz
Power consumption (max)   65W
On screen display   No
Video connection   BNC loopthrough, channel A/B
Dimensions (WxHxD)   Inch: 15.8x11.7x16.6
mm: 400x298x421
Operating temperature   0-40°C
Weight   30.8lb/14.0kg
Warranty   One year parts and labor
Approvals   UL1950, CSA22.2 950, 89/336/EEC, FCC Class A, FDA CFR21, EN55022 Class A, EN60950
Options   Rack Mounting Kit
Accessories   AC Power Cord
Operators Manual

 4 
 on: May 13, 2022, 04:57:46 pm 
Started by dmark - Last post by blusnowkitty
Using a spare wiring harness, ribbon cable ( including the  power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick

What model of monitor is that? Looks like a Conrac 38V44IOCA1?

https://www.ampronix.com/conrac-38v44ioca1-ivtm15a-15v44ioaap

 5 
 on: May 13, 2022, 04:08:33 pm 
Started by dmark - Last post by Lisa2
An alternative to using an extender is to use the chassis wiring outside of a chassis; I've been using a home-made extender on the power/video connector for quite some time, and use a drive/keyboard cable removed from a chassis for the other connector (instead of a second extender). I think others have all the wiring outside of the chassis, but maybe that is only practical with an external monitor.
Using a spare wiring harness, ribbon cable ( including the  power switch/ KB jack assembly ), and external monitor is how I run the card cage outside the chassis for debugging.
Rick



 6 
 on: May 12, 2022, 07:16:13 pm 
Started by blusnowkitty - Last post by compu_85
Great list!

There was also a parallel interface drive my by Sunol that worked with Unix on the Lisa. I think like the Corvus drive it hooks up to the stock parallel port.

-J

 7 
 on: May 12, 2022, 01:34:50 am 
Started by dmark - Last post by sigma7
... when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?

With tremedous thanks due to Al Kossow, the "original" Lisa schematics are available on Bitsavers.org, eg. the Lisa 1 or 2/5 I/O is at http://www.bitsavers.org/pdf/apple/lisa/hardware/050-4008-H_IO.pdf

Page 1 shows the card edge pinout, with pin 119 designated as /PWRSW, which will be tied to ground while the front panel power switch is pressed... possibly explaining your observation.

Pin 115 is +5V, which may show initially a low resistance to ground as there is a lot of capacitance that needs to be charged before reaching a steady state; after a few seconds of measuring resistance to ground, it should be more than a few ohms.

If you measure continuity using the "diode test" feature of a DMM (typically the feature that beeps when there is continuity), note that it can be misleading if one isn't paying sufficient attention to what you are measuring and how that feature works when not used to test diode junctions. Sometimes reversing the leads when using the diode test will quickly reveal that the connection isn't a direct one (since it beeps in one direction but not the other), but this may depend on the meter and circuit. Especially when troubleshooting mysteries, it may be preferable to stick with (or verify with) old fashioned resistance measurements, particularly when the difference between 1 ohm and 100 ohms makes a difference.

Your 12V supply may be a bit high due to minimal load on that rail. Since it is within 10% of 12V, it is probably fine.
+5V should be within +/- 5%, ie. 4.75V to 5.25V, so the power supply should be adjusted to that range.

HTH

 8 
 on: May 12, 2022, 12:22:56 am 
Started by dmark - Last post by dmark
Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively.  :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.

So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?

Seems like the voltages are probably normal, but suspect one lead of your voltmeter is on the +5 rail instead of ground, perhaps due to an error in the FAQ instructions...

Double check that the ground lead is at ground potential, eg. the end of C47 nearer the edge of the board. If voltages are still wonky, try putting the ground lead on the chassis (voltages won't be as accurate but not off by 5V).

And check the lead connections at your meter aren't reversed (eg. red to common, black to V) ... this sometimes trips me up.

Good luck!

You're right, when measuring off the negative side of C47 I get -12V and +12.9V (the latter seems high!)
What tripped me up, and this may betray how little I know about electronics, is that I thought pin 119 (as well as 115) on the I/O edge connector socket was ground, because when I test continuity between that pin and ground (i.e. the chassis), I get a dead short. But now I do see the 5V on pin 119 under operation. How can this be?

Anyhow, lesson learned that testing continuity with the chassis when the machine is turned off is not a reliable way to identify ground.

 9 
 on: May 11, 2022, 09:21:53 pm 
Started by dmark - Last post by sigma7
Now, the 5V rails look fine... But the 12V rails seem way out of whack on the I/O board. +7V and -17.5V respectively.  :o
Which is weird, because before I measured a clean +12V on the Lite Adapter board, so I assumed that the same rail was ok elsewhere!
Just to make sure, I pulled out the Lite Adapter board again and measured on the floppy header, and am still getting a very neat +12V there.

So... at least I have a concrete issue to track down. It's almost as if 5V is being subtracted (or negative voltage added I guess) to the 12V rails!?

Seems like the voltages are probably normal, but suspect one lead of your voltmeter is on the +5 rail instead of ground, perhaps due to an error in the FAQ instructions...

Double check that the ground lead is at ground potential, eg. the end of C47 nearer the edge of the board. If voltages are still wonky, try putting the ground lead on the chassis (voltages won't be as accurate but not off by 5V).

And check the lead connections at your meter aren't reversed (eg. red to common, black to V) ... this sometimes trips me up.

Good luck!

 10 
 on: May 11, 2022, 07:16:48 pm 
Started by blusnowkitty - Last post by pintoguy
I always wondered whether in fact the head dithers a bit off track when trying to recover from a read error. I know modern HDD's do it. Looks like perhaps FDD's do not ?

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