TI99
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Modems

02/03/06 18:00 Filed in: Computer
Modems
 
thursday, 02 march 2006 18:00

AcousticCoupler

Last night, I started checking my computer inventory for a modem that my sister could use to access the internet. I told her I would set her up with an old PC that I had, but discovered it had no modem built-in. I knew that I had a 56KB modem around here some where, but I have not found it yet. But what I did find was amazing, taking me back to 1979 and showing the changes that have evolved in home computer communications since then.

By the way, the term modem is short for modulator - demodulator. This is a way to convert a computer's digital data in a manner to transmit it over telephone lines. In the early days, this was done with an acoustic coupler in which a telephone handset was placed. These were built into old Teletype machines like I first used in 1969. The one shown here is from my first TI 99/4 home computer that I bought in 1979. These typically worked at 150 or 300 baud (bits per second). I also found other hardwired modems running at 1200, 2400, 4800, 9600 and 14,400 baud. As the technology advanced in speed, these would negotiate the highest speed they could operate on with the modem on the other end of the telephone line. When you dialed to connect to another computer, you would hear this chirpy, hashy noice, increasing in frequency until it matched what the other modem and the quality of your telephone connection could handle.

Starting around 2000, I have had Qwest DSL service that ran at about 256 Kbaud. Though I upgraded to their Deluxe DSL which was supposed to run up to 1.5 Mbaud, it never ran at half that speed and degraded back down to about the 256 Kbaud level last year. Finally, in December, I switched over to the Time-Warner Road Runner cable internet service. This evening, the cable modem speed has varied between 1.5 Mbaud and 4.8 Mbaud, probably averaging around 3 Mbaud. Imagine, over the last 25 years, we have experienced a 10,000 times increase in speed at least with a typical home computer. Dedicated commercial lines and the main internet trunk networks operate at much higher speeds.
 

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TI99 CF7+

03/05/10 13:22 Filed in: Computer
TI99 user group which is hosted by Yahoo! Groups.  This group has 619 members from all around the world and is very active with over 72000 messages in the past 10 years.  The group also has two user conferences in the Fall each year.  One conference is in Chicago while the other moves around in Europe.


I have a couple of new additions to my old TI99 computer systems in the last week [May 2010].  First, I now have 10 reconfigured cartridges that include brand new circuit boards with a 64k EPROMs.  These were developed, manufactured and distributed by members of the international
ti99-cf7
These new circuit boards include sockets for the 64k EPROMs which can be programmed with a long list of TI99 programs, some new and some old and very rare.  There are jumpers to configure the board for 8/16k, 32k or 64k EPROMS. I have three 64k versions, one with TI-Workshop and the other two set up as multicarts.  A multicart can hold up to 7 regular 8k programs along with a Multicart program that switches between them. The other 8 EPROMs are set up as 16 or 32k and include one program each.  It is possible to put multiple 16 or 32k programs on a 64k EPROM, but then the circuit board need to be modified with jumpers and switches.  Each new circuit card is mounted in an old TI-Invaders cartridge with a new label added. Additional information can be found at Jon Guidry's web site. Note that the cartridge with the white label in the picture is a multicart.
The second addition to my TI99 systems is a CF7+ Slim Profile card that attaches to the side port on the TI99/4A computer console as shown in the above picture.  This is normally where the PEB (Peripheral Expansion Box) cable attaches.  The CF7+ is circuit board that includes a Compact Flash memory card that emulates an array of floppy disks and three disk drives.  The number of floppies emulated depends upon the size of the CF.  A 32MB CF can emulate 39 floppies that can in turn be mounted on one of the three emulated drives.  The card also includes 32k of RAM that can be used to extend the main TI99 memory. The card includes a PIO parallel expansion port that can be used for a printer.  In essence, the CF7+ replaces a PEB with memory card, printer card and disk drives and controller.  The only limitation is that there is no serial RS232 port or other expansion capability.  I am not sure where the "7+" portion of the name comes from.  I think an earlier version did not have the PIO port or 32k RAM.  Earlier versions also extended outward from the TI99 console whereas this Slim Profile version has all components parallel to the side of the case and extends out only about 3/4 inch.  The card itself is 3 inches high by 3.5 inches long. [Since this was published, I obtained a version with an RS232 port in place of the PIO port]
Another part of the CF7+ system is software that runs on a Windows PC, Win98 on a Dell PC in my case. Two DOS programs come with the CF7+, a dsk2cf.exe to transfer .DSK images files to the CF and a cf2dsk.exe to backup CF volumes to the PC.  A CF To Disk Transfer Utility program that is a graphical front end to the previous two transfer programs and further documentation is available on Stuart Conner's web site.
 

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TI99 Update

28/06/09 18:00 Filed in: Computer


Dreambox

Recently, I purchased a Jaton X-Media Dreambox which converts TV and other video signals to SVGA for viewing on an LCD or other computer monitors. It was a $150 converter on sale for $30. My main reason to buy it was to eliminate a TV monitor that I was using on one of my TI99/4A computers which now can display on the Dell PC monitor. I actually use one of the A/V inputs leaving two other A/V and S-Video inputs that could be used with a DVD or VCR. A 15 pin computer monitor input allows switching to use the PC normally. There is also a regular TV/cable input and 125 channel analog tuner built-in so that broadcast TV can be watched. The converter also has an audio mini-jack input and output which is switched depending on the video input selection through a remote control or buttons on the box.

The picture above shows the A/V input which comes from the TI99 console shown in the first picture below. The Dell PC is connected through the Dreambox VGA input as well and the display is switched between the PV and the TI99. The other picture below shows the TI99 Peripheral Expansion Box with one internal 5 1/4 inch floppy drive and 2 external floppy drives.

TI99PCmonitor
TI99org
 
 
 

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TI99 Computer

09/03/06 18:00 Filed in: Computer
 
TI-99/4A Home Computer
TI99w2PEB

I purchased my first home computer in the Fall of 1979. After using an Apple II computer at work and investigating what was available, I decided to buy a Texas Instruments TI-99/4 computer. This was the first 16-bit personal computer, based on TI’s 9900 processor used in business computers. It also had several technical capabilities not seen in other personal computers. It had an accuracy of 13 digits based on its Radix 100 notation and a method on context switching found in Control Data mainframes. Unfortunately, it also used a double-interpreted BASIC making it slow since the base machine was programmed in GPL, a Graphic Programming Language.

My first TI-99/4 computer cost about $2500 with all the accessories. TI included a video monitor with the original console. It had a total of 16K bytes of memory built in, used programmed cartridges and stored BASIC programs on a cassette tape. I then added a 32KB memory expansion, an RS232 interface, a disk controller with two 5 1/4” floppy drives. These were all “sidecar” boxes about 7” wide, which along with a Speech Synthesizer and the 15” wide console, resulted in a computer train about 39” wide. [See the picture on the Home page.]

Later, TI came out with an upgraded TI-99/4A model and a Peripheral Expansion Box (PEB) that contained cards for each expansion connected to the console through a wide, shielded ribbon cable. The picture included here actually contains the 4A model with two PEBs that also contain two 5 1/4” floppy drives, a 3 1/2” floppy drive, a p-Code PASCAL card and an IDE interface card connected to a 2 GB hard drive. The bottom PEB is actually used just for its power supply and to mount the 3 1/2” floppy and hard drive. The IDE interface and HD were just added in December 2004. The console also has a cartridge expander that allows switching between three cartridges.
 

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