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electronizer

Member Since 12 Aug 2015
OFFLINE Last Active Mar 27 2019 12:03 PM

Topics I've Started

Help identifying 810 side board mods

Tue Mar 5, 2019 2:55 PM

I have two 810 side boards with what look like ROM upgrades, using piggybacked chips. One has a data separator board, the other doesnt:

Attached File  39BDB67C-1626-4DA8-8DF5-7942716A3728.jpeg   1.36MB   15 downloads

Attached File  4D9A81F3-716F-4FF5-AE43-3EEB0C2353F8.jpeg   1.41MB   15 downloads

I also have a side board with a windowed FDC:

Attached File  DFA80DB0-07E2-4826-9D81-1BB2A97A1DA7.jpeg   1.15MB   15 downloads

Are these of any interest for ROM dumps?

Apple II+ with clone Saturn RAM card that causes bad video

Thu Feb 28, 2019 7:50 PM

I recently got an Apple II+ with a clone of the Saturn 128 memory card installed. I have it connected via composite video out to a modern LCD TV. With the memory card installed, there is a lot of red and blue color bleed around text on the screen, and a bunch of vertical blue dashed lines that are continually pulsating. Without the memory card, the text is crystal clear. Interestingly, whenever I load a program on disk, the bad text and vertical lines clear up while the disk drive is running, then come back.

Bad:
Attached File  5984D52B-1C44-4594-8ACA-3B9913CB134B.jpeg   580.2KB   1 downloads

Good (while disk is running):
Attached File  34326460-D4B9-4CDC-8C49-8093A43B2540.jpeg   991.96KB   1 downloads

Is there any way to fix this? Should I find an official Apple 64k upgrade card and replace the clone Saturn card? Do I even need a memory upgrade? Im guessing yes because a lot of the games Id want to play probably require 64k.

Jaguar RGB cable—any difference between different video ground pins?

Fri Dec 7, 2018 6:19 PM

I'm building a Jaguar A/V connector to VGA (HD15) adapter that I can use with my standard VGA to RGBHV cable. I have a display capable of accepting composite sync so I'm planning to use the series 220uF + 680ohm resistor attenuation I've seen elsewhere on the TTL CSYNC output. For quick building, I'm using an IDC edge connector and a short piece of ribbon cable along with an HD15 plug with crimp connectors.

 

It's easiest to build this cable if I have separate ground wires coming off the ribbon cable for the video and sync ground connections. Pin 10 in my RGBHV cable is connected to sync ground for both Hsync and Vsync, and all of the RGB grounds in the cable are connected together, so really I just need two ground connections from the Jaguar.

 

I notice in the Jaguar schematic that there are four video grounds: 4A, 3B, 7B, and 10B. So, I could hook one of these to sync ground, and one of them to any one of the R/G/B grounds in the HD15 connector. I have two questions:

 

 

-The schematic shows a ferrite bead inductor on video ground 3B. Is there any advantage to using this ground over the other video ground connections, which don't have a ferrite bead?

 

 

-Is there any reason to connect all three RGB return pins as well as pin 5 in the HD connector to ground? (The VGA specification says pin 5 is Hsync ground, so e.g. would making these connections allow me to use a standard VGA cable to display an image with CSYNC connected in place of vertical sync?)


Help cracking internal Atari Tax demo (previously unknown?)

Tue Dec 4, 2018 12:26 AM

I finally got a chance to try again with the internal Atari Tax demo disks I found some time ago. With help from bob1200xl and a borrowed 800, I was able to get the disk to boot and we analyzed it. Looks like they moved the VTOC—there are a bunch of bad sectors where it should have been.

 

We copied over the good sectors to another disk—here's the atr file:

 

Attached File  HTDemo2.atr   90.02KB   42 downloads

 

Anyone want to try to crack this? Just in time for tax season, though I think there may have been one or two small changes to the tax laws since 1983...

 

 


Environmental monitoring story—early 80s microcomputer voice synthesis

Sun Sep 30, 2018 3:20 PM

Getting my 1400XL working and listening to the voice output of the Votrax SC-01 speech synthesizer reminded me of a much earlier experience I had with that chip, involving a project my dad worked on in the early 1980s.

My dad was the administrator for the Department of Zoology at the University of Wisconsin. One of my earliest memories of using a computer was when he would take me to his office and let me play with his Apple II Plus computer. He didnt have any games on it, but he would load up the text to speech software for the Sweet Talker voice synthesizer card installed in the computer and I would have a great time typing things for the computer to say in its funny robotic voice. I especially got a kick out of typing in gibberish and listening to the computer try to pronounce something like 20 Rs in a row.

Why did my dad have an Apple II Plus with a speech synthesizer? It served a very useful purpose.

The professors and graduate students at the Department of Zoology often ran experiments involving samples that needed to be kept cold. If the refrigeration for one of the 23 cold rooms maintained by the department failed over the weekend, much hard work would be lost. This happened enough that my dad started trying to think of a solution. He bought an Apple II Plus computer and had twisted pair wiring installed from his office to temperature sensors in each of the cold rooms. Enlisting the help of a friend who had programming experience, he wrote a monitoring program to continuously display temperatures for the different cold rooms. When the temperature was out of spec, the screen line for that room would flash in inverse. Now, my dad could monitor all the cold rooms from his office, and over the weekend he could stop by and quickly check to make sure everything was ok. However, my dad started wondering if there was a way he could ensure everything was working without having to go in to the office. If only there was some way to check from home! We didnt yet have our Atari computer, so we couldnt dial in with a modem to download the data remotely. However, we did have a telephone. Enter the voice synthesizer.

With the Sweet Talker and an AppleCat modem, my dad and his friend programmed the computer to literally call home any time there was a problem. I remember picking up the phone and hearing the strange robotic voice announce, There is a freezer alarm in room one-ten. Now the weekend trips to the office to check cold room temperatures were a thing of the past.

Im guessing all the hardware required to build this setup cost thousands of dollars. I cant help thinking that if the 1400XL had made it to production, it would have been the perfect solution for this application, and at a much lower price. Maybe Ill see if I can get my 1400XL to make some of those robotic phone calls I remember so fondly.