8800 Micro Disk Controller

Discuss the new Altair 8800 Micro

8800 Micro Disk Controller

Postby cnoyes72 » Jan Sun 08, 2012 1:21 am

Hello,

Is it possible to simply wire up a DB9 connector to the serial header on the disk controller board? I know there is the included USB to serial adapter, but is it possible to just use regular serial connection on those lines?

Otherwise, the disk controller board is running excellent (I did have to put some electrical tape on the bottom of the board to prevent shorting out on the two 10uf electrolytic caps on the main board. If I build another kit I may replace those with tantalum caps).


-CN
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Re: 8800 Micro Disk Controller

Postby galaga » Jan Sun 08, 2012 3:57 am

nope
you must have
http://benybee.wordpress.com/2008/01/13 ... converter/

or a usb2ttl converter is the easy way
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Re: 8800 Micro Disk Controller

Postby vbriel » Jan Sun 08, 2012 9:32 am

Not directly, here's why:

The serial to USB connector uses TTL or 5V signals to transmit data. A 1 bit is 5V and a 0 is ground or 0V. The RS232 voltage levels can have a max voltage of 25V (WAY out of TTL range). There quite a few chips out there that convert RS232 voltages to TTL and back again. The most common for hobbyists is the MAX232. This chip requires the 4 1uF caps (10uF is used a lot) caps on the chip to control the voltages. The MAX233 is more expensive (around $6) but has the capacitors built in. Connect this chip to the serial-USB connector, to 5V, GND and the DB9 or DB25 and you are all set.

I'm really trying to get away from the DB9 serial interface and that's why I decided not to put it on the 88DSKRAM interface.

Vince
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Re: 8800 Micro Disk Controller

Postby inerlogic » Sep Sun 06, 2015 1:31 am

Used an Arduino UNO as a USB->TTL level converter
(jumper RESET to GROUND on the UNO, TX->TX, RX->RX, GND->GND, expansion port pins 20-22)

with the connection hooked up on power up, i get a flashing light in the status light section (INP?)
unplugged the TX line and power cycled, hooked TX back up after boot, tap ENTER and i got an A prompt!

ran TREK80.... using PuTTY and TeraTerm for some reason the terminal windows keep minimizing.... not sure what that's all about....
i'd try linux and minicom, but i reformatted my linux box to install XP so i could run my EPROM programmer....
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Re: 8800 Micro Disk Controller

Postby Frotz661 » Dec Sat 12, 2015 6:16 am

FWIW, if you want an inexpensive and decent EPROM burner that will work with Linux, check out the MiniPRO TL866xx on Ebay. GPLed software for controlling it can be found at https://github.com/vdudouyt/minipro. The two variants of the MiniPRO are exactly the same, just the firmware is different. That means you can hack the firmware to add an ISP interface to the variant that doesn't have it.
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