The Digital Equipment Corporation VT420 terminal was released in 1990 and probably discontinued around 1993 or 1994. It was a Text and ANSI graphics only terminal like the VT320 and VT220 before it. It added a 50 line display capability and the ability to have two sessions on the screen, one for each serial port. This sample was produced in Taiwan. It used the two MMJ connectors for its serial ports but an option added a DB25 port for the first serial port. Mine is MMJ only. There was no graphics version. DEC kept the VT340 in production along with the VT420. This sample was produced in Taiwan. I think DEC may have moved production from China to Taiwan for all of their terminals.
Notice now that the logo is printed instead of emblossed like the previous terminals. The Digital logo is still embossed though.
The VT320 was the replacement for the VT220. It was released in 1987 I believe. Mine was made in 1990. It was smaller than the VT220 with a flatter screen better international character set support. Gone was the 20 mA current loop option. New for the VT320 was the DEC MMJ connector instead of industry standard connectors. The MMJ was Modified Modular Jack. Very similar to an RJ11 jack. One could file a bit of the tab on the RJ11 connector and make it fit in the MMJ jack. Screen colors available were amber, white and green.
Well VOX managed to kill my post so lets try this again.
The Digital Equipment Corporation VT240 terminal was the monochrome graphics capable version of the VT2xx series terminals. The VT241 was the color version. Both were the same base unit, just one shipped with a monochrome monitor and the other shipped with a color monitor. They support ReGIS and Tektronics graphics. ReGIS being the DEC graphics format which was also supported on the earlier VT125 and GIGI terminals. I spent the morning trying to find a file to display. But couldn't. But maybe I will create one later.
The VT240 consisted of a base unit, a keyboard such as the LK201 and a monitor such as the VR201. It actually used a stripped down PDP-11 processor (T-11). Thus you could use a terminal with a PDP-11 processor to connect to a PDP-11 with well a PDP-11 processor. The VT220 used an Intel processor as its main cpu.
On the rear of the base unit you have the RS232 communications port, an 20 mA current loop port, a composite video output on a BNC connector, a video output port on a DB15 connector with monochrome and color along with power, a printer port and the keyboard port.
Well finally figured out why I could not get the modems to work. Seems like there is enough limitation of audio bandwidth or noise that you can't use a V.34 modem on analog line with DSL superimposed. After editing register 56, my U.S. Robotics modem is now working.
I used a VT220 terminal and modem to call the local access line of Iglou.com. They run Shellaccess.com too. Each Iglou account comes with a Shellaccess account. That account is exactly that, a Unix shell account. So you can SSH you way to shellaccess.com and enjoy or....
What they don't advertise, you can call an Iglou analog access number and type shell after connecting. So I connected a modem to my VT220 terminal and with the appropriate Hayes comment (remember ATDT) called Iglou. Then I loaded a text web browser called Lynx.
Via VT220:
I prefer the VT220
My Last two posts on Vox
Mariser's City of God entry
And finally the Wiki entry on VT220 terminals
The VT-220 was a followup to the VT-100. It had the same screen size (I think they are the same). But it was way smaller. The VT-220 was introduced in 1983. What a difference 5 years made. It also had a video out so you could hook it to your big screen tv I guess. And some, this one included, had the 20ma interface option. It also had a serial printer output. On a DB9 (DE9 for you purists). However this was a different pinout that IBM chose to use on the IBM-AT in 1984. Also the LK-201 keyboard was introduced. It had the function keys on top like modern keyboards. It was perhaps the first to do so. It interfaced to the VT-220 with a modular cord, the same as a telephone handset but heavier gauge wire. It was also used on the PRO 300 series, some Vaxstations and the followups to the VT220. I think the VT-220 defined what we think of as a terminal more so than the VT-100.
This sample was bought from the University of Kentucky and bounced around our lab for years afterwards. It needs a good cleaning.
And we connected but then got disconnected. Should I call tech support?
Back in the day, before the internet, you had terminal emulation. What was the most common emulation required? VT-100. Well here is an actual VT-100 terminal. The VT-102 expanded version. The VT-100 series terminals were introduced in 1978 and replaced by the VT200 series in 1983. The basic form of communications would be a terminal attached to a modem calling to a remote system or a local terminal directly attached to a system. The VT-100 worked with either RS-232 or current loop interfaces. It was one of the first to support ANSI codes and of course it set the standard for text screens.
This sample I have had for quite a few years (8 or 10). A fellow collector of antique computers had won an eBay auction for it. The problem was he was in Spain and it was in the US. He could not afford to ship it to Spain. So he had it shipped to me and I told him I would send it to him when he got the money. We exchanged email a few times and then he lost interest. Found other hobbies I suppose.
I decided to show what it would be like to use the internet with a terminal In a way I did. For some reason, I was having connection issues and kept getting the dreaded "NO CARRIER" message. I am sure it is in my init string for the modem. I suppose tech support at my ISP will be of no use. "you are trying to connect with what?!?!?!?"
Below the VT-102, is a lowly DELL server. On it resides Saracom.com, Mariser.org and Catbees.com. It resides in an equipment rack I made.
Well, the internet could not have started without what is now the curse of those without broadband. Yep analog modems or if you prefer, modulator - demodulator. Here is a collection of some of the modems we have used over the years. I did not include any of the internal modems. I don't believe I have any of those left. They seemed to be less reliable and compatible than the externals. The speeds go from 300 bps to 56 Kbps not counting compression. The 300 bps modem is also 300 baud. Extra credit for those who know the difference between bps and baud rate. Mr LT and Dewitte excluded as we know you know the answer. One thing about modems is that cats (Gatita and Jessica) would come running to be petted when they heard the modem tones. It mean we humans were going to be sitted in front of the computer for a while.
Both DB-25 connector and the Radioshack serial DIN connector are present. Its the same RS-232 port just wired to both.
A real Hayes Smartmodem 1200. The second model of the Smartmodem. The first was a 300 baud released in 1981. The Smartmodem 1200 was released in 1982. This one however was manufactured in the early 1990s. It was purchased to be used for a special testbed at a local phone company. We went from the 300 baud Radioshack to a 2400 bps clone. 2400 was about as fast as you could go and still read the text coming across the screen.
The next modem is a 9600 bps clone. I think its a V.32 modem with no error correction. We got it in the early 1990s. Talk about speed!. I also used it to connect to the internet for the first time instead of just BBSes. It fairly much copied the Hayes look but with biege and steel instead of aluminum and black.
The last external modem we had and the last modem we actively used is a US Robotics V.Everything we got in the mid 1990s. US Robotics developed a highspeed modem before the V.32 standard was released and thus made a name for themselves. Later they would do that with the X2 modem before the V.90 standard was done. The V.Everything thing modem well did everything. Including 56K mode. actually no modems released in the U.S. actually did 56 Kbps across the phone lines. The download speed of 56 Kbps was lowered to meet FCC requirements on the phone lines. I believe at 56 Kbps, they exceeded the allowable analog encoded content for Part 68. Anyway, it had compression and thus actual throughput was significantly higher.
The nifty thing about the US Robotics modem is it has a mini-manual printed on the bottom.
Today we look atexternal storage devices. With modern personal computers the storage is often internal but on many early desktops, it was external to the CPU unit. I am not showing a cassette recorder as I assume many know what they look like.
From top left going clockwise, we have a Wang Laptop SCSI drive, 5.25 inch drive at 360K, DEC RRD42-DA SCSI Compact Disk Reader at 780 MB, DEC RD53 hard drive at 71 MB, HP 82902M, HP-IB interface 5.25 inch floppy drive at 270 KB, HP 82901M, HP-IB interface, dual 5.25 inch floppy drive at 270 KB each and a DEC RRD50 compact disk at 780MB. Grand total of external memory = 922 MB, not quite a GB.
Some ancient interfaces.
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Recent Comments
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Lauri said:
[this is good]You have an amazing brain, Lord K! Happy Thanksgiving to all ! :D read more
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Lord Kalvan said:
I am glad you liked the posts. This one post is basically the same as taking a Model A Ford... read more
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jaypo said:
I love your computer posts, LK. Every other word and picture is a complete mystery to me. I understand nothing.... read more
on NaBloPoMo - DEC VT-220 Part Two or How to Connect to the Internet without a Computer
Now I understand a wee part. Lots of awe left. read more
on NaBloPoMo - DEC VT-220 Part Two or How to Connect to the Internet without a Computer