LisaList2

Advanced search  

News:

2019.06.07 fixed NChat for the "Curve" theme, will eventually move it to its own page and add it to the default theme as well. Other plugins are next. see post in the Meta board for details

Pages: 1 ... 8 9 [10]
 91 
 on: April 25, 2022, 01:51:31 pm 
Started by pintoguy - Last post by patrick
I was thinking of swapping the whole card cage with my working Lisa 2/10, but this one is a 2/5 with the parallel port. And the 2/10 cage doesn't seem to fit very well. Would they be compatible ?

This will work as long as you do not connect any floppy or hard drives. The power harness is almost the same for the 2/5 and 2/10, but the drive harness is different.

 92 
 on: April 25, 2022, 01:39:20 pm 
Started by pintoguy - Last post by blusnowkitty
Have you tried twiddling the knobs on the affected Lisa's analog board? I know when I was trying to get my 2/5 up and running on its original battery damaged I/O board, the video signal was so overdriven the screen was mostly white with black smears here and there.

You could also have a broken component on your analog board. Mine apparently had been used so much that a plastic insulating tube on one of the coils broke apart. Fortunately there wasn't any electrical damage.

 93 
 on: April 25, 2022, 12:34:02 pm 
Started by pintoguy - Last post by pintoguy
mmm, I spoke too soon. The problem seems more complicated than I thought.

1) I checked the composite video signal, and it looks OK, and similar to what I get on a working Lisa (see pic)
2) I swapped the PS with my working Lisa, with same results
3) I swapped the Video board with my working Lisa, with same results
4) The CRT glows red

I was thinking of swapping the whole card cage with my working Lisa 2/10, but this one is a 2/5 with the parallel port. And the 2/10 cage doesn't seem to fit very well. Would they be compatible ? Should I force the 2/10 cage in ?

 94 
 on: April 24, 2022, 11:10:33 am 
Started by pintoguy - Last post by pintoguy
Thanks @blusnowkitty. I had read these posts, and this was going to be my next move.

 95 
 on: April 23, 2022, 11:31:23 pm 
Started by blusnowkitty - Last post by blusnowkitty
It would be easy to develop an adapter board that allows the use of a 6502 instead. But who needs something like that? I have made adapter boards for the Z8 (with UB8820M) and for the COP421 (with COP402). These parts have internal ROM and are therefore not so easy to replace, but even those no one has needed yet. They just break very rarely.

True, I see things more as a case of having and not needing than needing and not having. We've all seen just how bad leaky NiCd batteries can get, who's to say if things sit around long enough it won't rot the pins off other ICs? MOS-fabbed parts haven't stood the test of time either, if you look at how many Commodore computers have dead MOS chips (did Apple ever use MOS-fabbed ICs though? I think I've only seen Synertek or Rockwell). I also don't like the idea of condemning one vintage machine to ewaste to fix another (I suppose if the other machine had extensive physical board damage...), and 6504/6507s aren't exactly common on eBay US right now.

 96 
 on: April 23, 2022, 11:20:47 pm 
Started by pintoguy - Last post by blusnowkitty
Whack an old CRT TV/monitor with composite in on the Video Out port, or hook up a scope to the port and see if you have any signal at all - the video port is the same signal that gets fed into the Lisa's internal analog board. Video output is also on Pin 115 of the CPU board.

http://bitsavers.org/pdf/apple/lisa/hardware/lisa-motherboard-enhanced.pdf
https://lisa.sunder.net/cgi-bin/bookview2.cgi?zoom=0?image=0?book=6

 97 
 on: April 23, 2022, 08:18:10 pm 
Started by pintoguy - Last post by pintoguy
Update: I'm fairly happy with this repair. The color, height, and width match, and once the IO board is in place, it's hard to see the junction. I repaired all the traces, and the system looks like it's booting up: the on/off button is now dark and lights up upon switching. I can hear the speaker make some noise after 5 secs or so, then a series of beeps after ~15 secs: hi hi lo (no keyboard/mouse: expected) and hi hi hi (no startup device: also expected). But.... no video. I'm not too worried about this one, but who knows...

 98 
 on: April 23, 2022, 08:01:19 am 
Started by blusnowkitty - Last post by patrick
On the 6504, /IRQ is on pin 3, while the 6507 uses this pin as the RDY input. On the Lisa I/O board, /IRQ is not used and pin 3 is terminated with a pullup resistor. Therefore both 6504 and 6507 will work.

All 650x derivatives use the same chip. On the 28-pin variants, some pins are simply not connected. It would be easy to develop an adapter board that allows the use of a 6502 instead. But who needs something like that? I have made adapter boards for the Z8 (with UB8820M) and for the COP421 (with COP402). These parts have internal ROM and are therefore not so easy to replace, but even those no one has needed yet. They just break very rarely.


I did a quick bit of research and, at least according to the Atari guys there appears to be no reason why you couldn't use a full-blown vintage 6502 in place of a 6507. Things get more interesting by the time we get to the 65C02 (and by extension, the modern WDC parts) - I don't speak 6502 assembly, but according to the Atari guys code that uses illegal opcodes on a vintage 650x will no longer function on the 65C02. Another page I found said that illegal opcodes simply NOP in the 65C02, and some instructions may take an extra cycle or two to complete now.

The I/O ROM for the floppy controller does not use illegal opcodes. So I see no reason why a 65C02 (or 65C04 if there is such a thing) should not work.

You (or the Atari guys) are right -- the CMOS devices replaced the illegal opcodes (which are actually just overlays of two legal opcodes because the instruction decoding is incomplete) with either additional opcodes or NOPs. Unfortunately, there were different implementations of the 65C02 with different sets of additional opcodes. Therefore you have to know exactly which controller type is installed if you want to use them.
http://www.6502.org/tutorials/65c02opcodes.html


 99 
 on: April 22, 2022, 04:13:12 pm 
Started by blusnowkitty - Last post by stepleton
I don't know if it includes illegal instructions (I would be surprised if it did!), but you can find the source code for the 88 I/O ROM on Bitsavers:

http://bitsavers.org/pdf/apple/lisa/firmware/ROM88/
http://bitsavers.org/pdf/apple/lisa/firmware/IO_ROM_88_Listing_Dec83.pdf

 100 
 on: April 22, 2022, 02:16:43 pm 
Started by blusnowkitty - Last post by blusnowkitty
Speaking of replacement 65xx chips, I have had success using the 6507 in place of the of 6504 in the FDC section of the I/O board.  6507's are easier to find due to them being used in millions of Atari game systems.
After the supplies of 6504's and 6507's dry up, someone will have to work up an adapter to use a 6502 ( maybe a modern WDC version) on the Lisa IO card.

I did a quick bit of research and, at least according to the Atari guys there appears to be no reason why you couldn't use a full-blown vintage 6502 in place of a 6507. Things get more interesting by the time we get to the 65C02 (and by extension, the modern WDC parts) - I don't speak 6502 assembly, but according to the Atari guys code that uses illegal opcodes on a vintage 650x will no longer function on the 65C02. Another page I found said that illegal opcodes simply NOP in the 65C02, and some instructions may take an extra cycle or two to complete now.

Not speaking 6502 I couldn't disassemble the floppy ROM and tell you if this would be a problem... but it might be worth looking at to see if the floppy ROM would play nice with a WDC 65C02. On the bright side, if the floppy ROMs do have to be patched, at least there's only 3 floppy ROMs to patch (Twiggy, 400k, SunRem 800k) instead of thousands of Atari 2600 games?

https://atariage.com/forums/topic/194587-use-a-6502-instead-of-6507/
http://www.oxyron.de/html/opcodesc02.html

Pages: 1 ... 8 9 [10]