Handshaking on Serial Port 3

General discussions related to the Altair 8800 Clone

Re: Handshaking on Serial Port 3

Postby Caterman » November 29th, 2015, 2:32 pm

Just finished the refurb of this machine, had to manufacture a couple of hinge pins for the lid. It is a nice machine.
Still no luck with reading at anything higher than 4800, the literature I have seems to suggest 400cps for the GNT29 Reader. Not sure what's wrong.
It is solid at 4800 which I am very happy with.
Tried with a commercial serial cable still only worked up to 4800. But I can live with this, no problem.
As to the punch this has the GNT36 which should run at up to 75cps.
I would really like to try to punch at 600 baud but this is not a speed option on the Altair.
Do you think this could be a future option in a firmware update?
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Re: Handshaking on Serial Port 3

Postby AltairClone » November 30th, 2015, 12:03 pm

Yes, 600 baud can be added. I have a couple of other minor updates I want to add as well. I'll do that soon.

Mike
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Re: Handshaking on Serial Port 3

Postby AltairClone » December 1st, 2015, 12:35 pm

I have included 600 baud as an option in the new firmware release (version 1.9). See the "Announcements" forum for details.

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Re: Handshaking on Serial Port 3

Postby mail@gabrielegan.com » December 7th, 2015, 5:04 am

On my GNT 4604 the 8 dip-switches underneath have these functions:

1: Echo (1 for on)

2: Leader (1 for all holes punched, 0 for none)

3: DC codes (1 to use top panel setting)

4 & 5: Word length (00 = 8 bit parity check rec. data and read data;
10 = 8 bit parity check rec. data; 01 = 8 bit (ISO/EAI); 11= 7 bit ASCII)

6 & 7: Baud rate (00 = Lo 200 Med 300 High 4800; 10 = Lo 150 Med 300, High 2400;
01 = Lo 150 Med 300 High 1200; 11 = Lo 110 Med 600 High 600)

8: Conversion (0 = ASCII or ISO to EIA tape; 1 = ASCII code to ISO tape)

The "Lo/Med/High" speeds refer to the top panel settings.

What works for me (punching/reading with Altair clone) is the DIP settings of 00001001 and top panel of "Mode=CPU", "DC Codes=Off"; "Conv=Off";
"Speed=Med" (ie 300 baud).

Regards

Gabriel Egan
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Re: Handshaking on Serial Port 3

Postby Caterman » December 7th, 2015, 7:35 am

Thanks Gabriel, I am up and running with my GNT4604. I will check my DIP settings just to make sure.
Sorry, I transferred the update on my repairs to the machine on to the Announcement Board Firmware 1.9 thread.
You want to give 600 baud a try.
Just got a quote from Bill at GNT for a new drive motor.
Sitting down is required. Cost of motor = £299 plus VAT!!!!!
Fingers crossed my motor repair holds up.
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Re: Handshaking on Serial Port 3

Postby toml_12953 » February 12th, 2016, 8:17 am

AltairClone wrote:
The punch, however, is a different story. It can only run at 60-70 cps. Running at 600 baud will reduce output from a CSAVE command to just 60cps and not over-run the punch. However, the punch actually has a giant RAM buffer in it (it's newer technology than the Altair) and can receive and queue data at a full 9600 baud from the Altair and then feed it to the punch as fast as the punch can go.

Mike


My GNT4604 can read tapes at 4800 bps (the max. rate for the 4604) with no problem but only punches part of a tape when trying to punch at anything over 300 baud. I just ordered a manual for the 4604 but it hasn't come in yet. Does it have a cache (the 4604, not the manual!)? If so, is it possible the cache memory could be bad but the machine would still punch OK at low speed? Do GNT machines do any kind of self check on power up?

Tom L
Last edited by toml_12953 on February 12th, 2016, 3:41 pm, edited 1 time in total.
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Re: Handshaking on Serial Port 3

Postby toml_12953 » February 12th, 2016, 2:47 pm

AltairClone wrote:Mine is a 4606 vs 4604, that's why the differences.

The punches used are either 50cps (300 baud ok, 600 baud too fast) or 75cps (600 baud ok). The 4606 has a huge RAM buffer, so I can dump to it at 9600 and it feeds the punch as fast as it can from the buffer.

Not sure why reads aren't working at 9600. Let me know what you find.

Mike


I just found out that there are *two* models called 4604. The older one (which I have) is model KDVK-121xx which has a top speed of 4800 bps.
The other model is KDVK-141xx which has a top speed of 9600 bps. The KDVK-12xx doesn't even have a setting for 9600 bps.

* Update * I just bought a 4606 on eBay so my problems should be solved. Anyone want a used 4604 with manual cheap? I'll sell it here cheaper than if I put it on eBay.

That's just one perk of being an Altair Clone fan!

Tom L
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Re: Handshaking on Serial Port 3

Postby mail@gabrielegan.com » February 14th, 2016, 1:46 pm

Yes please, Tom, I'll take it off your hands. Contact me on <mail@gabrielegan.com>.
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